| Ingredients | Amount Per Serving |
|---|---|
|
(L-Histidine HCl)
|
130 mg |
| 37 mg | |
| 111 mg | |
| 80 mg | |
|
Alpha-Glucan Oligosaccharide
|
166 mg |
| 37 mg | |
| 750 mg | |
| 185 mg | |
| 185 mg | |
| 259 mg | |
|
(LPA)
|
200 mg |
| 37 mg | |
|
(5-Hydroxytryptophan)
|
25 mg |
| 148 mg | |
| 100 mg | |
| 74 mg | |
| 300 mg | |
| 200 mg | |
| 75 mg | |
|
(Suntheanine)
|
50 mg |
|
(as Lithium Citrate)
(Lithium (Form: as Lithium Citrate) )
|
2 mg |
Fiber Gum Acacia, natural Lemon flavor, Xylitol, Megna Sweet (Form: Licorice extract), Stevia powder, Citric Acid, Xanthan Gum
Below is general information about the effectiveness of the known ingredients contained in the product Amino Acid Neurotransmitter Formula. Some ingredients may not be listed. This information does NOT represent a recommendation for or a test of this specific product as a whole.
INSUFFICIENT RELIABLE EVIDENCE to RATE
INSUFFICIENT RELIABLE EVIDENCE to RATE
INSUFFICIENT RELIABLE EVIDENCE to RATE
INSUFFICIENT RELIABLE EVIDENCE to RATE
INSUFFICIENT RELIABLE EVIDENCE to RATE
INSUFFICIENT RELIABLE EVIDENCE to RATE
INSUFFICIENT RELIABLE EVIDENCE to RATE
INSUFFICIENT RELIABLE EVIDENCE to RATE
INSUFFICIENT RELIABLE EVIDENCE to RATE
INSUFFICIENT RELIABLE EVIDENCE to RATE
INSUFFICIENT RELIABLE EVIDENCE to RATE
INSUFFICIENT RELIABLE EVIDENCE to RATE
INSUFFICIENT RELIABLE EVIDENCE to RATE
INSUFFICIENT RELIABLE EVIDENCE to RATE
INSUFFICIENT RELIABLE EVIDENCE to RATE
INSUFFICIENT RELIABLE EVIDENCE to RATE
INSUFFICIENT RELIABLE EVIDENCE to RATE
INSUFFICIENT RELIABLE EVIDENCE to RATE
Below is general information about the safety of the known ingredients contained in the product Amino Acid Neurotransmitter Formula. Some ingredients may not be listed. This information does NOT represent a recommendation for or a test of this specific product as a whole.
POSSIBLY SAFE ...when used orally and appropriately. 5-HTP has been used safely in doses up to 400 mg daily for up to one year (913,30007,30130). Doses up to 1.2 grams daily have been used with apparent safety for up to 10 months (914,30018,30125,30164,30165). Doses of 3 grams daily have been used safely for 3 weeks (30138). There is some controversy about the safety of 5-HTP due to concerns for eosinophilia myalgia syndrome (EMS) (902,919,7067,10084,30178). There is speculation that only certain, contaminated 5-HTP products may cause this serious adverse effect (88174). So far, there is not enough evidence to know if EMS is caused by 5-HTP, contaminants, or other unknown factors (919,7067,10084).
POSSIBLY UNSAFE ...when used orally in large doses. Doses of 6-10 grams daily have been associated with severe gastrointestinal effects and hyperkinesis (30139,30183). The risk may be reduced if the dose is increased gradually.
PREGNANCY AND LACTATION:
Insufficient reliable information available; avoid using.
CHILDREN: POSSIBLY SAFE
when used orally and appropriately.
Doses of 5-HTP up to 5 mg/kg daily have been used safely for up to 3 years in infants and children up to 12 years old (30128,30153,88173).
There is some controversy about the safety of 5-HTP due to concerns for eosinophilia myalgia syndrome (EMS) (902,919,7067,10084,30178). There is speculation that only certain, contaminated 5-HTP products may cause this serious adverse effect (88174). So far, there is not enough evidence to know if EMS is caused by 5-HTP, contaminants, or other unknown factors (919,7067,10084).
LIKELY SAFE ...when used in amounts commonly found in foods.
POSSIBLY SAFE ...when used orally and appropriately. Alpha-alanine 100-140 mg/kg daily has been used with apparent safety for up to 3 months (16026,16027,16444). A single dose of alanine 40 grams has also been used with apparent safety (14612,16019,16020).
CHILDREN: POSSIBLY SAFE
when used orally and appropriately, short-term.
Alanine 90 mmol/L, as a component of an oral rehydration solution, has been used with apparent safety for approximately 48 hours in children age 3-48 months (16021).
PREGNANCY AND LACTATION: LIKELY SAFE
when used in amounts commonly found in foods.
There is insufficient reliable information available about the safety of using larger amounts as medicine during pregnancy or lactation.
LIKELY SAFE ...when used orally and appropriately. BCAAs 12 grams daily have not been associated with significant adverse effects in studies lasting for up to 2 years (68,72,73,74,10117,10146,10147,37120,92643,97531,103351,103352). ...when used intravenously and appropriately. BCAAs are an FDA-approved injectable product (13309).
CHILDREN: LIKELY SAFE
when used orally in dietary amounts of 71-134 mg/kg daily (11120,13308).
CHILDREN: POSSIBLY SAFE
when larger, supplemental doses are used orally and appropriately for up to 6 months (13307,13308,37127).
PREGNANCY:
Insufficient reliable information available; avoid using amounts greater than those found in food.
Although adverse effects have not been reported in humans, some animal research suggests that consumption of supplemental isoleucine, a BCAA, during the first half of pregnancy may have variable effects on birth weight, possibly due to abnormal placental development (103350).
LACTATION:
Insufficient reliable information available; avoid using amounts greater than those found in food.
Although the safety of increased BCAA consumption during lactation is unclear, some clinical research suggests that a higher concentration of isoleucine and leucine in breastmilk during the first 6 months postpartum is not associated with infant growth or body composition at 2 weeks, 2 months, or 6 months (108466).
LIKELY SAFE ...when used orally in amounts commonly found in foods.
POSSIBLY SAFE ...when used orally in medicinal amounts, short-term. GABA has been used with apparent safety in doses of 75 mg to 1.5 grams daily for up to one month in small clinical studies (19361,19363,19369,110134,110135). There is insufficient reliable information available about the safety of GABA when used orally for longer than one month or when used sublingually or intravenously.
PREGNANCY AND LACTATION:
Insufficient reliable information available; avoid using.
LIKELY SAFE ...when used orally and appropriately. Glutamine has been safely used in clinical research in doses up to 40 grams per day or 1 gram/kg daily (2334,2337,2338,2365,5029,5462,7233,7288,7293), (52288,52307,52308,52311,52313,52337,52349,52350,96516,97366). A specific glutamine product (Endari) is approved by the US Food and Drug Administration (FDA) (96520). ...when used intravenously. Glutamine has been safely incorporated into parenteral nutrition in doses up to 600 mg/kg daily in clinical trials (2363,2366,5448,5452,5453,5454,5458,7293,52272,52275), (52283,52289,52304,52306,52316,52341), (52359,52360,52371,52377,52381,52284,52385,52408,96637,96507,96516).
CHILDREN: LIKELY SAFE
when used orally and appropriately.
Glutamine has been shown to be safe in clinical research when used in amounts that do not exceed 0.7 grams/kg daily in children 1-18 years old (11364,46657,52321,52323,52363,86095,96517). A specific glutamine product (Endari) is approved by the US Food and Drug Administration for certain patients 5 years of age and older (96520). ...when used intravenously. Glutamine has been safely incorporated into parenteral nutrition in doses up to 0.4 grams/kg daily in clinical research (52338,96508). There is insufficient reliable information available about the safety of glutamine when used in larger amounts in children.
PREGNANCY AND LACTATION: LIKELY SAFE
when consumed in amounts commonly found in foods.
There is insufficient reliable information available about the safety of glutamine when used in larger amounts as medicine during pregnancy or lactation.
POSSIBLY SAFE ...when used orally and appropriately. Glycine has been used safely at doses up to 6 grams daily for 4 weeks (106497) and doses up to 9 grams daily for 3 days (10250,10251,10252,92319). There is insufficient reliable information available about the safety of glycine when used topically.
PREGNANCY AND LACTATION:
Insufficient reliable information available; avoid using.
LIKELY SAFE ...when used orally in the amounts found in foods.
POSSIBLY SAFE ...when used orally in larger amounts, short-term. L-histidine has been used with apparent safety in doses of up to 4 grams daily for up to 12 weeks (2347,2353,96311,108621), or in doses of up to 8 grams daily for up to 4 weeks (108620).
PREGNANCY AND LACTATION: LIKELY SAFE
when used orally in the amounts found in foods.
There is insufficient reliable information available about the safety of histidine when used in larger amounts during pregnancy or lactation.
POSSIBLY SAFE ...when used orally and appropriately. L-arginine has been used safely in clinical studies at doses of up to 24 grams daily for up to 18 months (3331,3460,3595,3596,5531,5532,5533,6028,7815,7816)(8014,8473,13709,31943,91195,91196,91963,99264,99267,110380)(110387). A tolerable upper intake level (UL) for arginine has not been established, but the observed safe level (OSL) of arginine intake established in clinical research is 20 grams (31996). ...when used intravenously and appropriately. Parenteral L-arginine is an FDA-approved prescription product (15). ...when used topically and appropriately. L-arginine appears to be safe when 5 grams is applied as a topical cream twice daily for 2 weeks or when a dentifrice is used at a dose of 1.5% w/w for up to 2 years (14913,96806). ...when inhaled, short-term. L-arginine appears to be safe when inhaled twice daily at a dose of 500 mg for up to 2 weeks (96807).
CHILDREN: POSSIBLY SAFE
when used orally in premature infants and children (8474,32286,96803,97392,110391).
...when used intravenously and appropriately (97392). Parenteral L-arginine is an FDA-approved prescription product (15). ...when used topically, short-term. A dentifrice containing L-arginine appears to be safe when used at a dose of 1.5% w/w for up to 2 years in children at least 3.7 years of age (96806). ...when inhaled, short-term. L-arginine appears to be safe when inhaled twice daily at a dose of 500 mg for up to 2 weeks in children at least 13 years of age (96807).
CHILDREN: POSSIBLY UNSAFE
when used intravenously in high doses.
Parenteral L-arginine is an FDA-approved prescription product (15). However, when higher than recommended doses are used, injection site reactions, hypersensitivity reactions, hematuria, and death have occurred in children (16817).
PREGNANCY: POSSIBLY SAFE
when used orally and appropriately, short-term.
L-arginine 12 grams daily for 2 days has been used with apparent safety in pregnancy during the third trimester (11828). L-arginine 3 grams daily has been taken safely during the second and/or third trimesters (31938,110379,110382). ...when used intravenously and appropriately, short-term. Intravenous L-arginine 20-30 grams daily has been used safely in pregnancy for up to 5 days (31847,31933,31961,31978).
LACTATION:
Insufficient reliable information available; avoid using.
LIKELY SAFE ...when used orally in amounts found in foods. There is insufficient reliable information available about the safety of L-cysteine when used orally in amounts greater than those found in foods or when used topically.
PREGNANCY AND LACTATION: LIKELY SAFE
when used orally in amounts found in foods.
There is insufficient reliable information available about the safety of amounts greater than those found in foods; avoid use. Some research suggests that taking L-cysteine during lactation increases levels of free L-cysteine in breastmilk. However, these levels are lower than those found in some commercial hydrolyzed protein infant formulas (109718).
LIKELY SAFE ...when lithium carbonate or lithium citrate is used orally and appropriately. Lithium carbonate and lithium citrate are FDA-approved drugs and have been used safely in clinical studies (15,97770). Lithium has a narrow therapeutic window and plasma levels must be monitored to avoid toxicity (15). Lithium levels should be drawn 12 hours after the last dose of lithium after steady state concentrations have been attained (approximately 3 days). Toxicity is most common at levels of 1.5 mEq/L, although some patients develop toxicity at levels less than 1 mEq/L (15,97770). There is insufficient reliable information available about the safety of lithium aspartate, lithium orotate, or other forms of supplemental lithium.
CHILDREN: POSSIBLY SAFE
when prescription lithium carbonate or lithium citrate is used orally and appropriately under medical supervision in children 7 years of age and older (15).
There is insufficient reliable information available about the safety of lithium aspartate, lithium orotate, or other forms of supplemental lithium.
PREGNANCY: POSSIBLY UNSAFE
when lithium carbonate and lithium citrate are used orally (15).
Lithium can cause fetal toxicity and increases the risk for cardiac and other abnormalities, including neural tube and urethral defects. However, it does not seem to increase the risk for preterm birth or low birth rate (15,9166,97770,104266). Some research suggests lithium might increase the risk for spontaneous abortion. Based on a meta-analysis of 2 population studies, taking lithium during pregnancy may increase the risk for spontaneous abortion when compared with the general population, but not when compared with patients with affective disorders not taking lithium during pregnancy (104266). This suggests that it may be the presence of affective disorder itself, or the possible associated use of other teratogenic drugs or substances during pregnancy, which may increase the risk for spontaneous abortion.
When the potential benefits to the mother and child outweigh the possible risk to the fetus, prescription lithium may be used with close monitoring by a healthcare professional (15,9166,97770,104266). The safety of lithium supplements during pregnancy is unknown.
LACTATION: LIKELY UNSAFE
when used orally.
Lithium is secreted into breast milk and may cause adverse effects in the nursing infant (15). Prescription lithium may be used in circumstances when the potential maternal benefits outweigh the possible risk to the infant. The infant should be closely monitored for signs of lithium toxicity (97770).
POSSIBLY SAFE ...when used orally in doses up to 3000 mg daily for up to one year (1114,1119,1120,90642,104104), or up to 6000 mg daily for up to 8 weeks (90644,90645). ...when used topically and appropriately, short-term (11051).
PREGNANCY AND LACTATION:
Insufficient reliable information available; avoid using.
LIKELY SAFE ...when used orally in amounts commonly found in food (94500).
POSSIBLY SAFE ...when used orally or intravenously and appropriately in medicinal amounts under the supervision of a healthcare professional (2410,2411,2413).
POSSIBLY UNSAFE ...when used orally or intravenously in excessive doses. Doses larger than 100 mg/kg should be avoided to prevent severe and potentially lethal cerebral effects (9339).
CHILDREN: LIKELY SAFE
when used orally in amounts commonly found in foods (94500).
CHILDREN: POSSIBLY SAFE
when used intravenously and appropriately (9338).
CHILDREN: POSSIBLY UNSAFE
when used intravenously in infants receiving parenteral nutrition.
In infants, blood methionine concentration can increase due to lower enzyme activity and inability to metabolize methionine. High levels of methionine can cause liver toxicity (9338).
PREGNANCY AND LACTATION: LIKELY SAFE
when used orally in amounts commonly found in food (94500).
There is insufficient reliable information available about the safety of methionine in medical doses during pregnancy and lactation; avoid using.
LIKELY SAFE ...when L-phenylalanine is consumed in amounts typically found in foods (11120).
POSSIBLY SAFE ...when L-phenylalanine is used orally in doses up to 100 mg/kg daily for up to 3 months (2463,2464,2466,2467,2469). ...when D-phenylalanine is used orally in doses up to 1 gram daily for up to 4 weeks, or as a single dose of 4-10 grams (2455,2456,2459,68795,104792). ...when DL-phenylalanine is used orally in doses up to 200 mg daily for up to 4 weeks (2468,68795,68825). ...when phenylalanine cream is applied topically, short-term (2461,92704).
PREGNANCY: LIKELY SAFE
when L-phenylalanine is consumed in amounts typically found in foods by pregnant patients with normal phenylalanine metabolism (2020,11120).
PREGNANCY: UNSAFE
when L-phenylalanine is consumed in amounts typically found in foods by pregnant patients with high serum phenylalanine concentrations, such as those with phenylketonuria (PKU).
Serum levels of phenylalanine greater than 360 micromol/L increase the risk of birth defects (1402,11468). Experts recommend that patients with high phenylalanine serum concentrations follow a low phenylalanine diet for at least 20 weeks prior to conception to decrease the risk for birth defects (1402).
There is insufficient reliable information available about the safety of L-phenylalanine when taken by mouth in large doses during pregnancy; avoid using.
There is insufficient reliable information available about the safety of oral D-phenylalanine during pregnancy; avoid using.
LACTATION: LIKELY SAFE
when L-phenylalanine is consumed in amounts typically found in foods by breast-feeding patients with normal phenylalanine metabolism (2020,11120).
There is insufficient reliable information available about the safety of L-phenylalanine when taken by mouth in medicinal amounts during lactation; avoid using. There is insufficient reliable information available about the safety of oral D-phenylalanine during lactation; avoid using.
LIKELY SAFE ...when L-serine is used orally in food amounts. Average dietary consumption of L-serine from combined food and supplemental sources ranges from 3.5-8 grams daily (91405).
POSSIBLY SAFE ...when used orally in medicinal amounts. D-serine 30 mg/kg (about 2 grams) orally daily for 6-16 weeks or 60 mg/kg (about 4 grams) daily for 4 weeks has been used with apparent safety (102202,102206,102214,102215,102237). L-serine up to 400 mg/kg (about 25 grams) daily for up to 1 year has been used with apparent safety (102204,102220,108550).
POSSIBLY UNSAFE ...when used orally in large doses. L-serine in doses greater than 400 mg/kg (about 25 grams) daily has caused reversible side effects including nausea, vomiting, nystagmus, and seizures (102204). D-serine 120 mg/kg (about 8 grams) or more daily might increase the risk of nephrotoxicity (102215).
PREGNANCY AND LACTATION:
Insufficient reliable information available.
Animal research in lactating mice shows that dietary L-serine transfers to milk and increases free L-serine while decreasing glutamic acid, L-alanine, D-alanine, and taurine levels in milk. However, this does not affect serine levels in the offspring (102228). It is unknown what effect supplemental serine may have in humans. Avoid using in amounts greater than those found in food.
LIKELY SAFE ...when used in amounts found in foods. Typical daily intakes for adults range from 40-400 mg (101471).
POSSIBLY SAFE ...when used orally and appropriately in medicinal amounts. Taurine 2-4 grams daily in two or three divided doses has been used safely in studies lasting up to 3 months (5248,5271,8217,8221,10454,77147,95612,98337,104165,104167). Higher doses of taurine 6 grams daily have been used safely in studies lasting up to 4 weeks (98336,98337). A risk assessment of orally administered taurine has identified an Observed Safe Level (OSL) of up to 3 grams daily for healthy adults (31996).
CHILDREN: LIKELY SAFE
when used in amounts found in foods.
CHILDREN: POSSIBLY SAFE
when used orally and appropriately in medicinal amounts.
Taurine 2.4-4.8 grams daily in three divided doses has been safely used in children 6-16 years of age for up to 12 weeks (103210).
PREGNANCY AND LACTATION: LIKELY SAFE
when used in amounts found in foods.
There is insufficient reliable information available about the safety of taurine when used in medicinal amounts during pregnancy and lactation; avoid using.
POSSIBLY SAFE ...when used orally and appropriately, short-term. L-theanine has been used safely in clinical research in doses of up to 900 mg daily for 8 weeks (12188,36439,96331,96332,96334,96341,97923,101986,104976). There is insufficient reliable information available about the safety of L-theanine when used long-term.
CHILDREN: POSSIBLY SAFE
when used orally and appropriately, short-term.
A specific L-theanine product (Suntheanine, Taiyo Kagaku) 200 mg twice daily has been used safely in males aged 8-12 years for up to 6 weeks (91744).
PREGNANCY AND LACTATION:
Insufficient reliable information available; avoid using.
LIKELY SAFE ...when used orally in food amounts. Threonine as L-threonine in doses of 7-14 mg/kg daily (about 0.5-1 gram daily) has been suggested to be the minimum amount required to maintain a positive nitrogen balance in humans and is generally considered to be safe (60072,94096).
POSSIBLY SAFE ...when used orally and appropriately in medicinal amounts. Taking threonine in doses up to 4 grams daily for up to 12 months seems to be safe (681,12056,12057,12059,60069).
PREGNANCY AND LACTATION:
Insufficient reliable information available; avoid using.
LIKELY SAFE ...when used orally in amounts commonly found in foods. Tyrosine has Generally Recognized as Safe (GRAS) status in the US (4912).
POSSIBLY SAFE ...when used orally and appropriately in medicinal amounts, short-term. Tyrosine has been used safely in doses up to 150 mg/kg daily for up to 3 months (7210,7211,7215). ...when used topically and appropriately (6155).
PREGNANCY AND LACTATION:
There is insufficient reliable information available about the safety of tyrosine during pregnancy and lactation when used in medicinal amounts.
Some pharmacokinetic research shows that taking a single dose of tyrosine 2-10 grams orally can modestly increase levels of free tyrosine in breast milk. However, total levels are not affected, and levels remain within the range found in infant formulas. Therefore, it is not clear if the increase in free tyrosine is a concern (91467).
Below is general information about the interactions of the known ingredients contained in the product Amino Acid Neurotransmitter Formula. Some ingredients may not be listed. This information does NOT represent a recommendation for or a test of this specific product as a whole.
Combining 5-HTP and carbidopa can increase the risk of serotonergic side effects.
 Details
Carbidopa is sometimes used with 5-HTP to minimize peripheral 5-HTP metabolism and boost the amount that reaches the brain. However, this combination might also increase the risk of some side effects including hypomania, restlessness, rapid speech, anxiety, insomnia, and aggressiveness (30076,30132,30158). Combining carbidopa and 5-HTP might also increase the risk of scleroderma-like skin changes due to elevated serotonin levels (1403).
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Theoretically, concomitant use of 5-HTP with medications that cause sedation might have additive effects.
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Combining serotonergic drugs with 5-HTP might cause additive serotonergic effects.
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5-HTP can increase serotonin levels and cause serotonergic effects (901). Theoretically, combining serotonergic drugs with 5-HTP might increase the risk of serotonergic side effects, including serotonin syndrome and cerebral vasoconstrictive disorders (8056). However, serotonin syndrome with 5-HTP has not yet been reported in humans (104941). Monitor patients for signs of serotonin syndrome and other serotonergic side effects if using 5-HTP with serotonergic drugs.
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Theoretically, BCAAs might alter the effects of antidiabetes medications.
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BCAAs in large doses can reduce the effects of levodopa.
Details
BCAAs may compete with levodopa for transport systems in the intestine and brain and decrease the effectiveness of levodopa (66,2719). Small clinical studies how that concomitant ingestion of protein or high doses of leucine or isoleucine (100 mg/kg) and levodopa can exacerbate tremor, rigidity, and the "on-off" syndrome in patients with Parkinson disease (3291,3292,3293,3294).
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Theoretically, taking GABA with antihypertensive drugs might increase the risk of hypotension.
Details
Some clinical research shows that GABA can decrease blood pressure in patients with hypertension (19367).
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Theoretically, GABA might have additive sedative effects when used in conjunction with CNS depressants. However, it is unclear if this concern is clinically relevant.
Details
Endogenous GABA has well-established relaxant effects (51152) and GABA(A) receptors have an established physiological role in sleep (51143). However, the effects of GABA supplements are unclear, as it is unknown whether exogenous GABA crosses the blood-brain barrier (51120,51153,90570). Although there have been limited reports of drowsiness or tiredness with GABA supplements (5115,19364), these effects have not been widely reported in clinical studies. Additionally, intravenous GABA 0.1-1 mg/kg has been shown to induce anxiety in a dose-dependent manner (5116).
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Theoretically, glutamine might antagonize the effects of anticonvulsant medications.
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Theoretically, glycine might decrease the effectiveness of clozapine.
Details
One small clinical study in patients with schizophrenia shows that adding glycine to clozapine therapy worsens symptoms of schizophrenia when compared with clozapine alone (10253). The mechanism of this interaction is unclear.
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Theoretically, concomitant use of L-arginine and ACE inhibitors may increase the risk for hypotension and hyperkalemia.
Details
Combining L-arginine with some antihypertensive drugs, especially ACE inhibitors, seems to have additive vasodilating and blood pressure-lowering effects (7822,20192,31854,31916). Furthermore, ACE inhibitors can increase potassium levels. Use of L-arginine has been associated with hyperkalemia in some patients (32213,32218). Theoretically, concomitant use of ACE inhibitors with L-arginine may increases the risk of hyperkalemia.
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Theoretically, concomitant use of L-arginine and ARBs may increase the risk of hypotension and hyperkalemia.
Details
L-arginine increases nitric oxide, which causes vasodilation (7822). Combining L-arginine with ARBs seems to increase L-arginine-induced vasodilation (31854). Furthermore, ARBs can increase potassium levels. Use of L-arginine has been associated with hyperkalemia in some patients (32213,32218). Theoretically, concomitant use of ARBs with L-arginine may increases the risk of hyperkalemia.
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Theoretically, concomitant use of L-arginine with anticoagulant and antiplatelet drugs might have additive effects and increase the risk of bleeding.
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Theoretically, concomitant use of L-arginine might have additive effects with antidiabetes drugs.
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Theoretically, concomitant use of L-arginine and antihypertensive drugs may increase the risk of hypotension.
Details
L-arginine increases nitric oxide, which causes vasodilation (7822). Clinical evidence shows that L-arginine can reduce blood pressure in some individuals with hypertension (7818,10636,31871,32201,32167,32225,31923,32232,110383,110384). Furthermore, combining L-arginine with some antihypertensive drugs seems to have additive vasodilating and blood pressure-lowering effects (7822,20192,31854,31916).
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Theoretically, concurrent use of isoproterenol and L-arginine might result in additive effects and hypotension.
Details
Preliminary clinical evidence suggests that L-arginine enhances isoproterenol-induced vasodilation in patients with essential hypertension or a family history of essential hypertension (31932).
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Theoretically concomitant use of potassium-sparing diuretics with L-arginine may increases the risk of hyperkalemia.
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Theoretically, concurrent use of sildenafil and L-arginine might increase the risk for hypotension.
Details
In vivo, concurrent use of L-arginine and sildenafil has resulted in increased vasodilation (7822,8015,10636). Theoretically, concurrent use might have additive vasodilatory and hypotensive effects. However, in studies evaluating the combined use of L-arginine and sildenafil for erectile dysfunction, hypotension was not reported (105065).
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Theoretically, concomitant use of L-arginine and testosterone might have additive effects.
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Theoretically, taking L-cysteine supplements with antidiabetes drugs might increase the risk of hypoglycemia.
Details
Animal research suggests that L-cysteine can have hypoglycemic effects (109722).
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Theoretically, taking lithium supplements with ACEIs might increase levels and adverse effects of lithium.
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Theoretically, taking lithium supplements with anticonvulsants might increase the risk of neurotoxicity.
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Theoretically, taking lithium supplements with antipsychotic drugs might increase the risk of encephalopathic syndrome.
Details
Encephalopathic syndrome has been reported in multiple patients taking prescription lithium and antipsychotics concomitantly. Symptoms have included weakness and lethargy, fever, confusion, and extrapyramidal symptoms. In some patients, resulting brain damage was irreversible. Although there is no established causal relationship between these symptoms and the combination of lithium and antipsychotic medications, there is a theoretical relationship (97770). It is unclear if this interaction would occur with the smaller doses found in lithium supplements.
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Theoretically, taking lithium supplements with calcium channel blockers might reduce lithium levels and might also increase the risk of certain adverse effects.
Details
Calcium channel blockers might reduce lithium concentrations. Monitor lithium levels with concurrent use. Calcium channel blockers might also increase the adverse neurological and gastrointestinal adverse effects of lithium (9,15). It is unclear if these interactions would occur with the smaller doses found in lithium supplements.
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Theoretically, taking lithium supplements with loop diuretics might increase lithium levels and adverse effects.
Details
Thiazide diuretics and loop diuretics might reduce lithium excretion, particularly in sodium-restricted patients (9,15). If lithium is clinically indicated and other treatment options are unavailable or inadequate in patients using diuretics, lithium treatment can be initiated with extreme caution. Serum lithium should be measured frequently and the doses used should be the lowest dose ordinarily tolerated (97770). It is unclear if this interaction would be clinically significant with the smaller doses found in lithium supplements.
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Theoretically, taking lithium supplements with methyldopa might increase the risk of lithium toxicity.
Details
Concurrent use of methyldopa with lithium increases the risk of lithium toxicity (9). It is unclear if this interaction would be clinically significant with the smaller doses found in lithium supplements.
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Theoretically, taking lithium supplements with methylxanthines might decrease lithium levels.
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Theoretically, taking lithium supplements with NSAIDs might increase lithium levels and adverse effects.
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Theoretically, taking lithium supplements with phenothiazines might decrease the levels and clinical effects of phenothiazines.
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Theoretically, taking lithium supplements with serotonergic drugs might both mask and increase the risk of serotonin syndrome.
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In a case report, a 67-year-old female with depression and bipolar disorder using lithium in combination with selective serotonin reuptake inhibitors (SSRIs) and other medications developed serotonin syndrome with symptoms of deep tendon hyperreflexia, muscle rigidity, tremor, and hyperthermia. However, agitation, one classical symptom of serotonin syndrome, was lacking. This was thought to be due to masking by lithium toxicity (105343). Lithium can increase serotonin levels (9,15), thus, combining serotonergic drugs with lithium might increase the risk of serotonergic side effects including serotonin syndrome and cerebral vasoconstrictive disorders. It is unclear if this interaction would occur with the smaller doses found in lithium supplements.
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Theoretically, taking lithium supplements with skeletal muscle relaxants might prolong neuromuscular blockade.
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Theoretically, lysine may reduce the effects of 5-HT4 agonists.
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Animal research suggests that L-lysine is a partial serotonin receptor 4 (5-HT4) antagonist and inhibits diarrhea induced by the 5-HT4 agonist, 5-hydroxytryptophane (19400).
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Concomitant intake of phenylalanine may reduce the intestinal absorption of baclofen.
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Phenylalanine and baclofen share the same intestinal carrier for absorption; phenylalanine competitively inhibits the absorption of baclofen, reducing its plasma levels (23788).
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Phenylalanine, especially in high doses, can reduce the effectiveness of levodopa.
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Theoretically, concomitant use of L-phenylalanine and non-selective MAOIs might increase the risk of hypertensive crisis.
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L-phenylalanine is metabolized to tyrosine (2052,9949). Some evidence suggests that L-phenylalanine, given with the non-selective MAOI pargyline, might prevent the elimination of tyramine, increasing the risk of hypertensive crisis (2021). However, this was not reported in a small number of patients when using L-phenylalanine with the partially selective MAO-B inhibitor, selegiline (2469).
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Theoretically, taurine might increase the risk of hypotension when taken with antihypertensive drugs.
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Theoretically, taurine might reduce excretion and increase plasma levels of lithium.
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Taurine is thought to have diuretic properties (3647), which might reduce the excretion of lithium.
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Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
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Theoretically, theanine might have additive sedative effects when used in conjunction with CNS depressants. However, it is unclear if this concern is clinically relevant.
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Theoretically, threonine might decrease the effects of NMDA antagonists.
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Theoretically, tyrosine might decrease the effectiveness of levodopa.
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Tyrosine and levodopa compete for absorption in the proximal duodenum by the large neutral amino acid (LNAA) transport system (2719). Advise patients to separate doses of tyrosine and levodopa by at least 2 hours.
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Theoretically, tyrosine might have additive effects with thyroid hormone medications.
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Tyrosine is a precursor to thyroxine and might increase levels of thyroid hormones (7212).
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Below is general information about the adverse effects of the known ingredients contained in the product Amino Acid Neurotransmitter Formula. Some ingredients may not be listed. This information does NOT represent a recommendation for or a test of this specific product as a whole.
General
...Orally, 5-HTP is generally well tolerated, short-term.
Most Common Adverse Effects:
Orally: Abdominal pain, anorexia, dizziness, diarrhea, drowsiness, fatigue, headache, insomnia, nausea, and vomiting. Severity appears to be dose-dependent.
Serious Adverse Effects (Rare):
Orally: Aggression, hallucinations, mania, severe gastrointestinal complaints.
Cardiovascular ...Orally, palpitations have been reported with 5-HTP (30076,30130,30167). Conversely, bradycardia has been reported in patients taking 5-HTP 0.4-2 grams daily in combination with carbidopa 100-300 mg daily (30132). In patients with schizophrenia, a combination of 5-HTP in doses up to 6 grams daily and carbidopa 150 mg daily was associated with diaphoresis and mild diastolic hypotension, especially when doses were increased at a rate faster than 200 mg per day (30183).
Dermatologic ...Orally, 5-HTP has been reported to cause urticaria, other allergic-type skin reactions, and flushing (2204,30000,30140). A scleroderma-like illness was reported in a 70-year-old man who had been taking 5-HTP 1400 mg daily and carbidopa 150 mg daily for 20 months. Elevated serotonin levels may be linked to this condition (1403).
Gastrointestinal ...Orally, 5-HTP has been reported to cause gastrointestinal side effects such as nausea, vomiting, abdominal or epigastric pain, heartburn, constipation, diarrhea, flatulence, anorexia, and taste alteration at any dose (2203,2204,30000,30112,30114,30125,30132,30139,30140)(30165,30183,104250). Severity may be dose-dependent and also related to how quickly doses are increased (30183). Some data suggests that these effects may diminish or disappear with continued use of 5-HTP (30132).
Hematologic ...Symptoms suggestive of eosinophilia myalgia syndrome (EMS) have been reported in some patients using 5-HTP (902,10084,30178,88174,90927). In one case, a woman was exposed to 5-HTP, tetrahydrobiopterin, carbidopa, and levodopa while administering them to her children for 2 years (90927). Her diagnosis was not confirmed, and the validity of the tests performed on the 5-HTP product has been questioned (88174). Other cases of eosinophilia or EMS in patients taking 5-HTP have been attributed to impurities that resemble previously identified contaminants found in L-tryptophan products (902,919,7067,10084). The L-tryptophan contaminants associated with EMS were linked to a specific manufacturer's production method that is not used in the preparation of 5-HTP (88174). Although 5-HTP supplements have been associated with EMS, it seems that this adverse effect is likely due to the presence of contaminants in the 5-HTP products, not 5-HTP itself.
Musculoskeletal ...Orally, rhabdomyolysis was noted in one patient with progressive myoclonus epilepsy who was treated with 5-HTP 300 mg daily for 21 days (30162).
Neurologic/CNS ...Orally, 5-HTP has been reported to cause drowsiness, dizziness, insomnia, fatigue, and headache (30076,30112,30132).
Psychiatric ...Orally, 5-HTP has been associated with euphoria, hypomania and mania, anxiety, insomnia, and aggressiveness (30076,30132,30158,88179). In patients with schizophrenia, a combination of high-dose 5-HTP, up to 6 grams daily, and carbidopa 150 mg daily was associated with transient increases in hallucinations, delusions, marked confusion, looseness of associations, flight of ideas, and a hyperkinetic syndrome consisting of restlessness, hand wringing, pacing, and an inability to sit quietly in a chair (30183).
General ...There is currently a limited amount of information on the adverse effects of alanine.
General
...Orally or intravenously, BCAAs are generally well tolerated.
Most Common Adverse Effects:
Orally: Abdominal distension, diarrhea, nausea, vomiting.
All routes of administration: High doses can lead to fatigue and loss of motor coordination.
Cardiovascular ...Orally, a single case of hypertension following the use of BCAAs has been reported (37143).
Dermatologic ...Orally, a single case of skin blanching following the use of BCAAs has been reported (681). It is not known if this effect was due to use of BCAAs or other factors.
Gastrointestinal ...Orally, BCAAs can cause nausea, vomiting, diarrhea, and abdominal distension. Nausea and diarrhea has been reported to occur in about 10% of people taking BCAAs (10117,37143,92643,97531).
Neurologic/CNS ...Orally and intravenously, BCAAs can cause fatigue and loss of motor coordination due to increased plasma ammonia levels (693,694,10117). Short-term use of 60 grams of BCAAs containing leucine, isoleucine, and valine for 7 days in patients with normal metabolic function seems to increase levels of ammonia, but not to toxic plasma levels (10117). However, liver function should be monitored with high doses or long-term use (10117). Due to the potential of increased plasma levels of ammonia and subsequent fatigue and loss of motor coordination, BCAAs should be used cautiously before or during activities where performance depends on motor coordination (75). Orally, BCAAs may also cause headache, but this has only been reported in one clinical trial (681).
General
...Orally, GABA seems to be generally well tolerated.
Sublingually, no adverse effects have been reported. However, a thorough evaluation of safety outcomes has not been conducted.
Most Common Adverse Effects:
Orally: Drowsiness, gastric upset, minor throat burning, muscle weakness, and nausea.
Cardiovascular ...Intravenously, GABA can cause dose-related increases in blood pressure and pulse (5116).
Gastrointestinal ...Orally, minor throat burning has been associated with GABA in one study (5115). In another study in which GABA was administered with phosphatidylserine, one patient experienced severe gastric distress, two patients reported moderate nausea, and one reported constipation (19364). Children with cerebral palsy taking GABA experienced nausea and decreased appetite (19362).
Genitourinary ...In one study, one patient treated with oral GABA and phosphatidylserine reported transient amenorrhea (19364).
Musculoskeletal ...Orally, minor adverse effects associated with GABA included muscle weakness (5115).
Neurologic/CNS ...Orally, GABA may cause drowsiness or tiredness (5115,19364). Four children with cerebral palsy taking GABA had convulsions, and an unspecified number experienced motor restlessness. However, causality of these adverse effects was not clear, and the dose of GABA was not specified (19362). Intravenously, GABA 50 mg has been associated with a "lack of alertness" in healthy female volunteers (51159).
Psychiatric ...Intravenously, GABA 0. 1-1.0 mg/kg has been shown to induce anxiety, dysphoria, and mood disturbances in a dose-dependent manner (5116).
Other ...In one study, patients taking GABA experienced a slight warming of the body (19370).
General
...Orally and intravenously, glutamine is generally well tolerated.
Most Common Adverse Effects:
Orally: Belching, bloating, constipation, cough, diarrhea, flatulence, gastrointestinal pain, headache, musculoskeletal pain, nausea, and vomiting.
Endocrine ...One case of hot flashes has been reported in a patient taking glutamine 5-15 grams orally twice daily for up to 1 year (96520).
Gastrointestinal ...Orally, glutamine has been associated with belching, bloating, constipation, flatulence, nausea, vomiting, diarrhea, and gastrointestinal (GI) pain. Nausea, vomiting, constipation, diarrhea, and GI pain have been reported in clinical trials using high-dose glutamine 10-30 grams (0.3 grams/kg) in two divided doses daily to treat sickle cell disease (99414). One case of dyspepsia and one case of abdominal pain have been reported in patients taking glutamine 5-15 grams twice daily orally for up to 1 year (96520). In a small trial of healthy males, taking a single dose of about 60 grams (0.9 grams/kg of fat free body mass [FFM]) was associated with a 50% to 79% incidence of GI discomfort, nausea, and belching, compared with a 7% to 28% incidence with a lower dose of about 20 grams (0.3 gram/kg FFM). Flatulence, bloating, lower GI pain, and urge to regurgitate occurred at similar rates regardless of dose, and there were no cases of heartburn, vomiting, or diarrhea/constipation (105013). It is possible that certain GI side effects occur only after multiple doses of glutamine.
Musculoskeletal ...Orally, glutamine 30 grams daily has been associated with cases of musculoskeletal pain and non-cardiac chest pain in clinical trials for patients with sickle cell disease (99414).
Neurologic/CNS ...Orally, glutamine has been associated with dizziness and headache. A single case of dizziness has been reported in a patient treated with oral glutamine 0.5 grams/kg. However, the symptom resolved after reducing the dose to 0.25 grams/kg (91356). Mania and hypomania have been reported in 2 patients with bipolar disorder taking commercially purchased glutamine up to 4 grams daily (7291). Glutamine is metabolized to glutamate and ammonia, both of which might have neurological effects in people with neurological and psychiatric diseases or in people predisposed to hepatic encephalopathy (7293).
Oncologic ...There is some concern that glutamine might be used by rapidly growing tumors and possibly stimulate tumor growth. Although tumors may utilize glutamine and other amino acids, preliminary research shows that glutamine supplementation does not increase tumor growth (5469,7233,7738). In fact, there is preliminary evidence that glutamine might actually reduce tumor growth (5469).
Other ...Orally, glutamine has been associated with cough when a powdered formulation is used. It is unclear if this was due to accidental inhalation. One case of a burning sensation and one case of hypersplenism has been reported in a patient taking glutamine 5-15 grams twice daily orally for up to 1 year (96520).
General ...Orally and topically, glycine seems to be well tolerated.
Gastrointestinal ...Soft stools, nausea, vomiting, and upper gastrointestinal (GI) tract discomfort have occurred rarely with oral use of glycine. These symptoms resolve rapidly with discontinuation of glycine (10252,11320,92319). Dry mouth has also been reported but any association to glycine is unclear (92321).
Neurologic/CNS ...Mild sedation has occurred rarely with oral use of glycine. Symptoms resolve rapidly with discontinuation of glycine (10252,11320,92321). Irritability, insomnia, fatigue, memory impairment, headache, and sensory impairment have been reported, but any association with glycine is unclear (92321).
General ...Orally, histidine has been used with apparent safety in clinical research; however, a thorough evaluation of safety outcomes has not been conducted.
General
...Oral, intravenous, and topical L-arginine are generally well tolerated.
Most Common Adverse Effects:
Orally: Abdominal pain, bloating, nausea, diarrhea, headache, insomnia, flushing.
Intravenously: Excessively rapid infusion can cause flushing, headache, nausea and vomiting, numbness, and venous irritation.
Cardiovascular ...L-arginine taken orally by pregnant patients in a nutrition bar containing other antioxidants was associated with a 36% greater risk of palpitations when compared with a placebo bar (91197). It is unclear if this effect was due to L-arginine, other ingredients, or other factors.
Dermatologic ...Orally, arginine can cause flushing, rash, and hives (3460,32138,102587,104223). The skin reactions were likely of allergic etiology as oral L-arginine has been associated with eosinophilia (32138). In one case report, intravenous administration caused allergic reactions including urticaria, periorbital edema, and pruritus (11830). Excessively rapid infusion of L-arginine has caused flushing, local venous irritation, numbness. Extravasation has caused necrosis and superficial phlebitis (3330,16817).
Gastrointestinal
...Orally, L-arginine has been reported to cause nausea, diarrhea, vomiting, dyspepsia, gastrointestinal discomfort, and bloating (1363,31855,31871,31972,31978,32261,90198,91197,96811,99243)(102587,102592).
Orally, L-arginine has been reported to cause esophagitis in at least six adolescents. Symptoms, which included pain and dysphagia, occurred within 1-3 months of treatment in most cases (102588). There are at least two cases of acute pancreatitis possibly associated with oral L-arginine. In one case, a 28-year-old male developed pancreatitis after consuming a shake containing 1.2 grams of L-arginine daily as arginine alpha-ketoglutarate. The shake also contained plant extracts, caffeine, vitamins, and other amino acids. Although there is a known relationship between L-arginine and pancreatitis in animal models, it is not clear if L-arginine was directly responsible for the occurrence of pancreatitis in this case (99266).
Intravenously, excessively rapid infusion of L-arginine has been reported to cause nausea and vomiting (3330,16817).
Musculoskeletal ...Intravenous L-arginine has been associated with lower back pain and leg restlessness (32273). Orally, L-arginine has been associated with asthenia (32138).
Neurologic/CNS ...Orally, L-arginine has been associated with headache (31855,31955,32261,91197,102587,102592), insomnia, fatigue (102587,102592), and vertigo (32150,102592).
Oncologic ...In breast cancer patients, L-arginine stimulated tumor protein synthesis, which suggests stimulated tumor growth (31917).
Pulmonary/Respiratory ...When inhaled, L-arginine can cause airway inflammation and exacerbation of airway inflammation in asthma (121). However, two studies assessing oral L-arginine in patients with asthma did not detect any adverse airway effects (31849,104223).
Renal ...Intravenously, L-arginine has been associated with natriuresis, kaliuresis, chloruresis, and systemic acidosis (32225). Orally, L-arginine can cause gout (3331,3595).
Other ...Orally, L-arginine has been associated with delayed menses, night sweats, and flushing (31855).
General ...Orally, L-cysteine is well tolerated in amounts found in foods. When used in higher doses or when applied topically, no adverse effects have been reported. However, a thorough evaluation of safety outcomes has not been conducted.
General
...Orally, prescription forms of lithium are generally well tolerated when used as prescribed.
Plasma levels must be monitored to avoid toxicity. It is unclear how the lower doses of lithium found in supplements may alter the occurrence and likelihood of these adverse effects.
Most Common Adverse Effects:
Orally: Edema, fatigue, fine tremor, gastrointestinal symptoms, lethargy, muscle weakness, polydipsia, polyuria, skin conditions, vertigo, and weight gain.
Cardiovascular ...Orally, lithium has been reported to cause bradyarrhythmia. A case of symptomatic bradycardia due to sinoatrial node dysfunction is reported in a patient with bipolar disorder who took lithium orotate 20 mg daily for 5 years, despite a serum lithium level in the therapeutic range (111327). Deep vein thrombosis is also reported in 2 patients with bipolar disorder who experienced toxic serum levels of lithium (111329). It is unclear if these effects are a concern with the smaller doses found in lithium supplements.
Dermatologic ...Orally, lithium can cause or exacerbate skin disorders such as hair loss, acne, psoriasis, and rash (9,15,97770). A case of Stevens-Johnson syndrome is also reported in a patient with bipolar disorder who took lithium carbonate at an unknown dose for 17 days (111317).
Endocrine ...Orally, chronic use of lithium has been reported to cause various endocrine disorders. Case reports associate chronic lithium use with hypothyroidism, hyperthyroidism, goiter, hyperparathyroidism, and diabetes insipidus (9,15,104267,104269,104270,104271,111320). In one case report, a 68-year-old male with schizophrenia developed severe hypothyroidism resulting in myxedema coma after taking oral lithium carbonate. He recovered after discontinuation of lithium and administration of levothyroxine. At least two other cases of lithium-associated myxedema coma have been reported (97740). At least 4 cases of lithium-associated hyperparathyroidism have been reported in females aged 53-68 years that had taken lithium for 24 years or more. These patients presented with hypernatremia, hypercalcemia, elevated serum creatinine, thyroid or parathyroid abnormalities, and nephrogenic diabetes insipidus (104269,105344). It is unclear if these effects are a concern with the smaller doses found in lithium supplements.
Gastrointestinal ...Orally, lithium can cause gastrointestinal symptoms. These adverse effects often improve with continued use (9). It is unclear if this effect would occur with the smaller doses found in lithium supplements.
Musculoskeletal ...Orally, lithium can cause muscle weakness. This adverse effect often improves with continued use (9). It is unclear if this effect would occur with the smaller doses found in lithium supplements.
Neurologic/CNS ...Orally, lithium can cause vertigo, muscle weakness, lethargy, fatigue, and a dazed feeling. These adverse effects often improve with continued use. Fine tremor can occur and may persist with continued use. Chronic use of lithium can cause mild cognitive and memory impairment, particularly in the presence of dehydration or hyponatremia (9,15,97745). These long-term neurological adverse effects of lithium are potentially due to accumulation in the central nervous system even when blood levels appear within the therapeutic range (97745). Lithium-associated hyperparathyroidism-induced hypercalcemia has resulted in hallucinations, confusion, insomnia, and agitation (105344). A case of delirium and transient difficulty with word finding is reported in a patient with bipolar disorder treated with lithium 250-500 mg twice daily and 9 sessions of electroconvulsive therapy (111316). A case of mild encephalitis/encephalopathy with a reversible splenial lesion (MERS) is also reported in a patient with bipolar disorder who had a toxic lithium level of 1.94 mEq/L (111318). It is unclear if these effects would occur with the smaller doses found in lithium supplements.
Psychiatric ...Abrupt discontinuation of lithium resulting in a rapid reduction in serum lithium levels can precipitate recurrence of bipolar symptoms (9165). Lithium should be tapered gradually over at least 14 days (9165).
Renal ...Orally, lithium can cause polyuria, polydipsia, and edema (9). Chronic lithium use has been reported to cause central or nephrogenic diabetes insipidus, hypocalciuric hypercalcemia, and nephrotic syndrome (104269,104271,111314,111319). Long-term lithium use is estimated to increase the odds of chronic kidney disease (CKD) by at least 2-fold and may contribute to CKD progression (111315,111324). It is unclear if these effects would occur with the smaller doses found in lithium supplements.
Other ...Orally, chronic use of lithium has been reported to cause an irreversible reduction in taste and smell in a patient with bipolar disorder who took 400-1000 mg/day for 4 months (111313). Chronic use of lithium 1200 mg/day has also been reported to cause dysphagia in a 17-year-old patient with bipolar disorder; however, the patient's serum lithium level was in the toxic range and the adverse effect resolved once the level normalized (111328). It is unclear if these effects would occur with the smaller doses found in lithium supplements.
General
...Orally and topically, lysine is generally well tolerated.
Most Common Adverse Effects:
Orally: Abdominal pain, diarrhea, and dyspepsia.
Gastrointestinal ...Orally, lysine has been reported to cause diarrhea and abdominal pain, including dyspepsia (1114,1115,1116,1118,1120).
Renal ...There is one case report of oral lysine use associated with tubulointerstitial nephritis progressing to chronic renal failure in a 44-year old female (1121).
General
...Orally, methionine is well tolerated when used in amounts commonly found in foods.
Intravenously, methionine is generally well tolerated.
Most Common Adverse Effects:
All ROAs: Dizziness, drowsiness, hypotension, irritability, and vomiting. Methionine may also cause headache, increased homocysteine levels, increased urinary calcium excretion, and leukocytosis.
Serious Adverse Effects (Rare):
All ROAs: Cerebral edema, hepatic encephalopathy. In infants, intravenous methionine has been linked to liver toxicity.
Cardiovascular ...Orally or intravenously, methionine can cause hypotension (9339,9340). High-dose methionine (75-100 mg/kg daily) may increase plasma concentrations of homocysteine, which is a risk factor for vascular disease (63112,63114,63115). However, a study of patients with type 2 diabetes and a history of cardiovascular disease (CVD) showed that methionine loading did not increase homocysteine concentrations, and that a cause-effect relationship between increased intake of methionine and endothelial dysfunction has not been clearly established (63110).
Gastrointestinal ...Orally or intravenously, methionine can cause vomiting (9339,9340).
Genitourinary ...Orally or intravenously, methionine may increase urinary calcium excretion (9340,63112,94095).
Hematologic ...Orally or intravenously, methionine may cause leukocytosis when used at a dose of 8-13. 9 grams daily for 4-5 days (9340).
Hepatic ...A single dose of 8 grams of methionine has reportedly caused hepatic encephalopathy in patients with cirrhosis (9340). Long-term use of methionine-containing parenteral nutrition solution has been linked to liver toxicity in infants (9338).
Neurologic/CNS
...Orally or intravenously, methionine can cause dizziness, drowsiness, headache, and irritability (9339,9340,94095).
A case of cerebral edema ultimately leading to death has been reported in a patient receiving methionine 100 mg/kg orally. The post-load plasma concentrations of methionine were substantially higher in this patient than those previously reported in humans receiving this usual oral loading dose, leading the authors to postulate that an overdose of methionine may have been administered erroneously. This can occur when plasma methionine levels rise above 3000 mcmol/L (9339). Another case of progressive cerebral edema associated with high methionine levels and betaine (N,N,N-trimethylglycine) therapy in a patient with cystathionine beta-synthase (CBS) deficiency has been reported (63119). The authors stated that the cerebral edema was most likely precipitated by the betaine therapy, but that the exact mechanism is uncertain.
Oncologic ...Although one case-control study of incident, histologically-confirmed gastric cancer has indicated that a diet rich in methionine, salt, and nitrite is associated with an increased risk of gastric cancer (2409), a large observational study that adjusted for multiple factors, including sodium intake, has found no association between high dietary intake of methionine and gastric cancer (108041).
General
...Orally, L-phenylalanine and D-phenylalanine are generally well tolerated when used in typical doses.
Most Common Adverse Effects:
Orally: Anxiety, constipation, headache, heartburn, insomnia, nausea, and sedation.
Topically: Burning, erythema, and itching.
Cardiovascular ...One patient in a small case series developed extrasystoles after 10 days of treatment with DL-phenylalanine, but this resolved on the 12th day of treatment without discontinuing phenylalanine (68825).
Dermatologic ...Topically, erythema, itching, and burning have been reported in some patients using an undecylenoyl phenylalanine 2% cream for treatment of age spots (92704).
Gastrointestinal ...Orally, constipation, heartburn, and nausea has been reported in some patients taking phenylalanine (2463,68827,68829,68830).
Neurologic/CNS
...Orally, headaches, which are typically transient and do not require treatment or dosage reduction, have been reported during the first 10 days of treatment with L-, D-, and DL-phenylalanine (68795,68825,68827,68829).
Transient vertigo has also been reported with D- and DL-phenylalanine (68795).
In patients with Parkinson disease, taking DL-phenylalanine, especially in high doses, interferes with levodopa transport into the brain, causing increased rigidity, tremor, and occurrence of the on-off phenomenon. Akinesia has been reported more rarely (3291,3292,3293,3294,68828). In patients with schizophrenia, taking a single dose of L-phenylalanine 100 mg/kg has been associated with worsening of medication-induced tardive dyskinesia (2457).
Psychiatric ...Orally, L-phenylalanine has been associated with anxiety, insomnia, and, more rarely, hypomania (68827,68829). DL-phenylalanine has been associated with fatigue and sedation (9951).
General
...Orally, L-serine and D-serine seem to be well tolerated in medicinal doses.
Side effects appear to be dose-dependent.
Most Common Adverse Effects:
Orally: Gastrointestinal distress, including abdominal pain, bloating, dyspepsia, loss of appetite, and nausea.
Serious Adverse Effects (Rare):
Orally: Seizures with high doses of L-serine.
Gastrointestinal ...Orally, D-serine 120 mg/kg (about 8 grams) daily has been reported to cause gastrointestinal distress (102215). L-serine 5-30 grams daily has been reported to cause abdominal pain, dyspepsia, bloating, nausea, and loss of appetite (102204,102220).
Genitourinary ...Orally, D-serine 120 mg/kg (about 8 grams) daily for 4 weeks has been reported to cause proteinuria without glycosuria or creatine elevation. Proteinuria resolved completely after discontinuation of serine (102215).
Hepatic ...Orally, D-serine 120 mg/kg (about 8 grams) daily has been reported to cause asymptomatic transaminitis which resolved after discontinuation of serine (102215).
Immunologic ...Orally, in one very small, exploratory study, patients taking L-serine 400 mg/kg (about 25 grams) daily for one year had a higher rate of localized infections than those taking placebo (102204). Whether ingestion of L-serine caused or increased the risk of these infections is unknown.
Neurologic/CNS ...Orally, D-serine 120 mg/kg (about 8 grams) daily has been reported to cause insomnia after a single dose (102215). Taking L-serine in doses greater than 400 mg/kg (about 25 grams) can cause reversible nystagmus and seizures (102204).
General
...Orally, taurine is generally well-tolerated when used in typical doses for up to one year.
Most Common Adverse Effects:
Orally: Constipation, diarrhea, and dyspepsia.
Serious Adverse Effects (Rare):
Orally: Hypersensitivity reactions in sensitive individuals. Case reports raise concerns for serious cardiovascular adverse effects, but these reports have involved energy drinks containing taurine and other ingredients. It is unclear if these adverse effects are due to taurine, other ingredients, or the combination.
Cardiovascular ...Changes in heart rate and increased blood pressure have been reported following the co-administration of taurine and caffeine, although the effects of taurine alone are unclear (77088). In healthy individuals, consumption of energy drinks containing taurine increased platelet aggregation and decreased endothelial function (77151,112268,112741). A case of cardiac arrest following strenuous exercise and an excessive intake of energy drinks containing caffeine and taurine has been reported (77136). In another case report, a 28-year-old male without cardiovascular risk factors presented to the hospital with radiating chest pain, shortness of breath, and diaphoresis after excessive intake of an energy drink containing taurine, caffeine, sugar, and glucuronolactone. Electrocardiogram findings confirmed myocardial infarction, and subsequent catheterization confirmed thrombotic occlusion (112741).
Endocrine ...Orally, taurine has been reported to cause hypoglycemia (77153).
Gastrointestinal ...Orally, constipation has been reported following the administration of taurine (77231). Dyspepsia has also been reported after oral taurine use (104165).
Hematologic ...In clinical research, taurine reduced platelet aggregation (77245). A case of massive intravascular hemolysis, presenting with confusion, dark urine, dyspnea, emesis, and fever, has been reported following the administration of a naturopathic vitamin infusion containing taurine, free amino acids, magnesium, and a vitamin B and D complex (77177). However, the effects of taurine alone are unclear.
Immunologic ...A case report describes a hypersensitivity reaction in a female patient with a history of allergies to sulfonamides, sulfites, and various foods, after ingestion of taurine and other sulfur-containing supplements. The amount of taurine in the products ranged from 50-500 mg per dose. The allergic reaction recurred upon rechallenge with taurine 250-300 mg (91514).
Neurologic/CNS
...In a case study, encephalopathy occurred in a body-builder who took approximately 14 grams of taurine in combination with insulin and anabolic steroids.
It is not known if this was due to the taurine or the other drugs taken (15536).
Cases of seizures following the consumption of energy drinks containing taurine have been reported (77105,77196). In clinical research, taurine has been reported to cause drowsiness and ataxia in epileptic children (77241).
Psychiatric ...In a case report, a 36-year-old male with adequately controlled bipolar disorder was hospitalized with symptoms of mania after consuming several cans of an energy drink containing taurine, caffeine, glucuronolactone, B vitamins, and other ingredients (Red Bull Energy Drink) over a period of four days (14302). It is unknown if this effect was related to taurine.
Pulmonary/Respiratory ...In human research, an exacerbation of pulmonary symptoms of cystic fibrosis has been associated with taurine supplementation, although this could also be caused by progression of the disease (77231).
Renal ...A case of acute kidney failure has been reported following the concomitant intake of 1 liter of vodka and 3 liters of an energy drink providing taurine 4. 6 grams, caffeine 780 mg, and alcohol 380 grams (77185).
General
...Orally, L-theanine seems to be well tolerated.
Most Common Adverse Effects:
Orally: Drowsiness, headaches.
Neurologic/CNS
...Orally, L-theanine may cause headaches (36439).
Patients have also reported drowsiness, increased duration of sleep, and increased dream activity after oral L-theanine use (96331).
A case of subtle facial tic starting within 4 days of taking L-theanine 400 mg daily has been reported for a pediatric patient. Although the tics reportedly ceased once theanine was discontinued, the child had exhibited tics in the past. Therefore, the adverse effect was not thought to be related to L-theanine (91744).
General ...Orally, threonine seems to be well tolerated.
Dermatologic ...Orally, skin rash has been reported in people who have taken threonine (681).
Gastrointestinal ...Orally, some patients can experience minor gastrointestinal upset including diarrhea (12056). Other side effects reported in people who have taken threonine include flatus and constipation (681).
Neurologic/CNS ...Orally, headache has been reported in people who have taken threonine (681).
Pulmonary/Respiratory ...Orally, rhinorrhea has been reported in people who have taken threonine (681).
Other ...Orally, a two-fold increase in serum ammonia levels occurred in one patient following administration of threonine 4 grams daily (681).
General
...Orally, tyrosine seems to be well tolerated.
No serious adverse effects have been documented; however, a thorough evaluation of safety outcomes has not been conducted.
Most Common Adverse Effects:
Orally: Fatigue, headache, heartburn, and nausea.
Gastrointestinal ...Orally, tyrosine can cause nausea and heartburn when taken at a dose of 150 mg/kg (7211). Taking tyrosine 4 grams daily in combination with 5-hydroxytryptophan 800 mg and carbidopa 100 mg can cause diarrhea, nausea, and vomiting. These effects can be mitigated by lowering the dosage (918).
Musculoskeletal ...Orally, larger doses of tyrosine (150 mg/kg) can cause arthralgia, but this is uncommon (7211).
Neurologic/CNS ...Orally, larger doses of tyrosine (150 mg/kg) can cause headache and fatigue (7211). Taking a combination of tyrosine 4 grams, 5-hydroxytryptophan 800 mg, and carbidopa 100 mg can cause drowsiness and agitation. These effects can be mitigated by lowering the dosage (918).
