Each capsule contains: St. John's Wort herb extract standardized to 0.3% Hypericin 300 mg • Kava Kava 100 mg • Vitamin B6 25 mg. Other Ingredients: Gelatin, Rice Powder, Magnesium Stearate.
Brand name products often contain multiple ingredients. To read detailed information about each ingredient, click on the link for the individual ingredient shown above.
Below is general information about the effectiveness of the known ingredients contained in the product St. John's Wort Plus. 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
Below is general information about the safety of the known ingredients contained in the product St. John's Wort Plus. 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, short-term. Kava extracts have been used safely in clinical trials under medical supervision for up to 6 months (2093,2094,2095,4032,7325,15046,15130,18314,18316,18318)(18320,29663,29671,98980,102086,112642). Historically, there has been some concern that kava preparations could induce hepatotoxicity and liver failure in patients taking relatively normal doses, short-term. At least 100 cases of liver toxicity following kava use have been reported. Although liver toxicity is more frequently associated with prolonged use of very high doses (6401,57346), in some cases the use of kava for as little as 1-3 months has been associated with the need for liver transplants, and even death (390,7024,7068,7086,7096,17086,57252)(57254,57297). However, some experts question the clinical validity of several of these cases (11369,11371).
PREGNANCY: POSSIBLY UNSAFE
when used orally.
There is some concern that pyrone constituents in kava can cause loss of uterine tone (19); avoid using.
LACTATION: POSSIBLY UNSAFE
when used orally.
There is concern that the toxic pyrone constituents of kava can pass into breast milk (19); avoid using.
LIKELY SAFE ...when used orally and appropriately. St. John's wort extracts in doses up to 900 mg daily seem to be safe when used for up to 12 weeks (3547,3550,4835,5096,6400,6434,7047,13021,13156,13157)(14417,76143,76144,89666,89669,95510). Some evidence also shows that St. John's wort can be safely used for over one year (13156,13157,76140), and may have better tolerability than selective serotonin reuptake inhibitors (SSRIs) and tricyclic antidepressants (TCAs) (4897,76153,76143,104036).
POSSIBLY SAFE ...when used topically and appropriately. St. John's wort 0.5% extract seems to be safe when used once weekly for 4 weeks (110327). St. John's wort oil has been used with apparent safely twice daily for 6 weeks (110326). However, topical use of St. John's wort can cause photodermatitis with sun exposure (110318).
POSSIBLY UNSAFE ...when used orally in large doses. St. John's wort extract can be unsafe due to the risk of severe phototoxic skin reactions. Taking 2-4 grams of St. John's wort extract (containing hypericin 5-10 mg) daily appears to increase the risk of photosensitivity (758,4631,7808).
PREGNANCY: POSSIBLY UNSAFE
when used orally.
Preliminary population research has found that taking St. John's wort while pregnant is associated with offspring that develop neural tube, urinary, and cardiovascular malformations. Subgroup analyses suggest that these risks may be higher when taking St. John's wort during the first trimester when compared with the second or third trimester. However, more research is needed to confirm these findings (106052). Animal-model research also shows that constituents of St. John's wort might have teratogenic effects (9687,15122). Until more is known, St. John's wort should not be taken during pregnancy.
LACTATION: POSSIBLY UNSAFE
when used orally.
Nursing infants of mothers who take St. John's wort have a greater chance of experiencing colic, drowsiness, and lethargy (1377,15122,22418); avoid using.
CHILDREN: POSSIBLY SAFE
when used orally, and appropriately, short-term.
St. John's wort extracts in doses up to 300 mg three times daily seem to be safe when used for up to 8 weeks in children aged 6-17 years (4538,17986,76110).
LIKELY SAFE ...when used orally and appropriately in doses that do not exceed the tolerable upper intake level (UL) of 100 mg daily for adults (15). ...when used parenterally and appropriately. Injectable vitamin B6 (pyridoxine) is an FDA-approved prescription product (15).
POSSIBLY SAFE ...when used orally and appropriately in doses of 101-200 mg daily (6243,8558).
POSSIBLY UNSAFE ...when used orally in doses at or above 500 mg daily. High doses, especially those exceeding 1000 mg daily or total doses of 1000 grams or more, pose the most risk. However, neuropathy can occur with lower daily or total doses (6243,8195). ...when used intramuscularly in high doses and frequency due to potential for rhabdomyolysis (90795).
CHILDREN: LIKELY SAFE
when used orally and appropriately (3094).
CHILDREN: POSSIBLY SAFE
when used orally and appropriately in amounts exceeding the recommended dietary allowance (5049,8579,107124,107125,107135).
CHILDREN: POSSIBLY UNSAFE
when used orally in excessive doses, long-term (3094).
PREGNANCY: LIKELY SAFE
when used orally and appropriately.
A special sustained-release product providing vitamin B6 (pyridoxine) 75 mg daily is FDA-approved for use in pregnancy. Vitamin B6 (pyridoxine) is also considered a first-line treatment for nausea and vomiting in pregnancy by the American College of Obstetrics and Gynecology (111601). However, it should not be used long-term or without medical supervision and close monitoring.
PREGNANCY: POSSIBLY UNSAFE
when used orally in excessive doses.
There is some concern that high-dose maternal vitamin B6 (pyridoxine) can cause neonatal seizures (4609,6397,8197).
LACTATION: LIKELY SAFE
when used orally in doses not exceeding the recommended dietary allowance (RDA) (3094).
The RDA in lactating women is 2 mg daily. There is insufficient reliable information available about the safety of vitamin B6 when used in higher doses in breast-feeding women.
Below is general information about the interactions of the known ingredients contained in the product St. John's Wort Plus. 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 kava with alcohol may increase the risk of sedation and/or hepatotoxicity.
 Details
Kava has CNS depressant effects (11373,18316). Concomitant use of kava with other CNS depressants can increase the risk of drowsiness and motor reflex depression (2093,2098). Additionally, kava has been associated with over 100 cases of hepatotoxicity. There is some concern that kava can adversely affect the liver, especially when used in combination with hepatotoxic drugs (7024,7068,7086,7096,17086,57346). Clinical practice guidelines from a joint taskforce of the World Federation of Societies of Biological Psychiatry (WFSBP) and the Canadian Network for Mood and Anxiety Treatments (CANMAT) recommend that alcohol not be used with kava (110318). |
Combining kava with CNS depressants can have additive sedative effects.
Details
Kava has CNS depressant effects (11373,18316). Concomitant use of kava with other CNS depressants can increase the risk of drowsiness and motor reflex depression (2093,2098). Clinical practice guidelines from a joint taskforce of the World Federation of Societies of Biological Psychiatry (WFSBP) and the Canadian Network for Mood and Anxiety Treatments (CANMAT) recommend that CNS depressants, including alcohol and benzodiazepines, not be used with kava (110318).
|
It is unclear if kava inhibits CYP1A2; research is conflicting.
Details
Although in vitro research and a case report suggest that kava inhibits CYP1A2 (8743,12479,88593), more robust clinical evidence shows that kava has no effect on CYP1A2. In a clinical study in healthy volunteers, taking kava 1000 mg twice daily (containing a daily dose of 138 mg kavalactones) for 28 days had no effect on CYP1A2 activity (13536,98979).
|
Theoretically, kava might increase levels of CYP2C19 substrates.
Details
|
Theoretically, kava might increase levels of CYP2C9 substrates.
Details
|
It is unclear if kava inhibits CYP1A2; research is conflicting.
Details
|
Kava might increase levels of CYP2E1 substrates.
Details
In a clinical study in healthy volunteers, taking kava 1000 mg twice daily (containing a daily dose of 138 mg kavalactones) for 28 days inhibited the metabolism of CYP2E1 substrates (13536).
|
It is unclear if kava inhibits CYP3AA; research is conflicting.
Details
Although in vitro research suggests that kava inhibits CYP3A4 (8743,12479), more robust clinical evidence shows that kava has no effect on CYP3A4. In a clinical study in healthy volunteers, taking kava 1000 mg twice daily (containing a daily dose of 138 mg kavalactones) for 28 days had no effect on CYP3A4 activity (13536,98979).
|
Combining kava and haloperidol might increase the risk of cardiovascular adverse effects and hypoxia.
Details
Atrial flutter and hypoxia has been reported for a patient who received intramuscular injections of haloperidol and lorazepam after using kava orally. The side effects were attributed to kava-induced inhibition of CYP2D6, but might also have been related to additive adverse effects with the concomitant use of haloperidol, lorazepam, and kava (88593).
|
Theoretically, using kava with hepatotoxic drugs might increase the risk of liver damage.
Details
|
It is unclear if kava inhibits P-glycoprotein (P-gp); research is conflicting.
Details
In vitro research shows that kava can inhibit P-gp efflux (15131). However, a clinical study in healthy volunteers shows that taking kava standardized to provide 225 mg kavalactones daily for 14 days does not affect the pharmacokinetics of digoxin, a P-gp substrate (15132,98979). It is possible that the use of other P-gp substrates or higher doses of kava might still inhibit P-gp.
|
Taking kava with ropinirole might increase the risk for dopaminergic toxicity.
Details
A case of visual hallucinations and paranoid delusions has been reported for a patient who used kava in combination with ropinirole. The adverse effects were attributed to kava-induced inhibition of CYP1A2, which may have reduced the metabolism of ropinirole, resulting in excessive dopaminergic stimulation (88593).
|
St. John's wort increases the clearance of alprazolam and decreases its effects.
Details
Alprazolam, which is used as a probe for cytochrome P450 3A4 (CYP3A4) activity, has a two-fold increase in clearance when given with St. John's wort. St. John's wort reduces the half-life of alprazolam from 12.4 hours to 6 hours (10830).
|
St. John's wort may increase the clearance of ambristentan and decrease its effects.
Details
Clinical research in healthy volunteers shows that taking St. John's wort 900 mg daily decreases the area under the concentration-time curve of ambrisentan 5 mg by 17% to 26%. Ambrisentan clearance was increased by 20% to 35% depending on CYP2C19 genotype. However, these small changes are unlikely to be clinically significant (99511).
|
St. John's wort might have additive phototoxic effects with aminolevulinic acid.
Details
Concomitant use with St. John's wort extract may cause synergistic phototoxicity. Delta-aminolevulinic acid can cause a burning erythematous rash and severe swelling of the face, neck, and hands when taken with St. John's wort (9474).
|
St. John's wort might decrease the levels and clinical effects of boceprevir.
Details
Boceprevir increases the maximum concentration and concentration at 8 hours of the St. John's wort constituent, hypericin, by approximately 30%. However, St. John's wort does not significantly change the area under the concentration-time curve or maximum plasma concentration of boceprevir 800 mg three times daily in healthy adults (95507,96552).
|
St. John's wort might reduce the levels and effects of bupropion.
Details
Clinical research shows that taking St. John's wort 325 mg three times daily for 14 days along with bupropion reduces the area under the concentration-time curve by approximately 14% and increases the clearance of bupropion by approximately 20%. This effect is attributed to the induction of cytochrome P450 2B6 (CYP2B6) by St. John's wort (89662).
|
St. John's wort might increase the levels and effects of clopidogrel.
Details
Taking St. John's wort with clopidogrel seems to increase the activity of clopidogrel. In clopidogrel non-responders, taking St. John's wort seems to induce metabolism of clopidogrel to its active metabolite by cytochrome P450 enzymes 3A4 and 2C19. This leads to increased antiplatelet activity (13038,89671,96552). Theoretically, this might lead to an increased risk of bleeding in clopidogrel responders.
|
St. John's wort might decrease the levels and clinical effects of clozapine.
Details
A case report describes a female with schizophrenia controlled on clozapine who had a return of symptoms when she started taking St. John's wort. The plasma concentration of clozapine was reduced, likely because its clearance was increased due to induction of the cytochrome P450 enzymes 3A4, 1A2, 2C9, and 2C19 by St. John's wort (96552).
|
St. John's wort increases the clearance of contraceptive drugs and reduces their clinical effects.
Details
Females taking St. John's wort and oral contraceptives concurrently should use an additional or alternative form of birth control. St. John's wort can decrease norethindrone and ethinyl estradiol levels by 13% to 15%, resulting in breakthrough bleeding, irregular menstrual bleeding, or unplanned pregnancy (11886,11887,13099). Bleeding irregularities usually occur within a week of starting St. John's wort and regular cycles usually return when St. John's wort is discontinued. Unplanned pregnancy has occurred with concurrent use of oral contraceptives and St. John's wort extract (9880). St. John's wort is thought to induce the cytochrome P450 1A2 (CYP1A2), 2C9 (CYP2C9), and 3A4 (CYP3A4) enzymes, which are responsible for metabolism of progestins and estrogens in contraceptives (1292,7809,9204).
|
St. John's wort reduces the levels and clinical effects of cyclosporine.
Details
Concomitant use can decrease plasma cyclosporine levels by 30% to 70% (1234,4826,4831,4834,7808,9596,10628,96552). Using St. John's wort with cyclosporine in patients with heart, kidney, or liver transplants can cause subtherapeutic cyclosporine levels and acute transplant rejection (1234,1293,1301,6112,6435,7808,9596). This interaction has occurred with a St. John's wort extract standardized to 0.3% hypericin and dosed at 300-600 mg per day (6435,10628). Withdrawal of St. John's wort can result in a 64% increase in cyclosporine levels (1234,4513,4826,4831,4834). St. John's wort induces cytochrome P450 3A4 (CYP3A4) and the multi-drug transporter, P-glycoprotein/MDR-1, which increases cyclosporine clearance (1293,1340,9204,9596).
|
St. John's wort may increase the metabolism and reduce the levels of CYP1A2 substrates.
Details
|
St. John's wort may increase the metabolism and reduce the levels of CYP2B6 substrates.
Details
Clinical research shows that taking St. John's wort 325 mg three times daily for 14 days along with bupropion, a CYP2B6 substrate, reduces the area under the concentration-time curve by approximately 14% and increases the clearance of bupropion by approximately 20% (89662).
|
St. John's wort may increase the metabolism and reduce the levels of CYP2C19 substrates.
Details
Preliminary clinical research in healthy males shows that taking St. John's wort for 14 days induces CYP2C19 and increases metabolism of mephenytoin (Mesantoin). In patients with wild-type 2C19 (2C19*1/*1) metabolism was almost 4-fold greater in subjects who received St. John's wort compared to placebo. In contrast, patients with 2C19*2/*2 and *2/*3 genotypes did not demonstrate a similar increase in metabolism (17405). Theoretically, St. John's wort might increase metabolism of other CYP2C19 substrates.
|
St. John's wort may increase the metabolism and reduce the levels of CYP2C9 substrates.
Details
There is contradictory research about the effect of St. John's wort on CYP2C9. Some in vitro research shows that St. John's wort induces CYP2C9, but to a lesser extent than CYP3A4 (9204,10848,11889). St. John's wort also induces metabolism of the S-warfarin isomer, which is a CYP2C9 substrate (11890). Other research shows that St. John's wort 300 mg three times daily for 21 days does not significantly affect the pharmacokinetics of a single 400 mg dose of ibuprofen, which is also a CYP2C9 substrate (15546). Until more is known, use St. John's wort cautiously in patients who are taking CYP2C9 substrates.
|
St. John's wort increases the metabolism and reduces the levels of CYP3A4 substrates.
Details
|
St. John's wort reduces the levels and clinical effects of digoxin.
Details
St. John's wort can reduce the bioavailability, serum levels, and therapeutic effects of digoxin. Taking an extract of St. John's wort 900 mg, containing hyperforin 7.5 mg or more, daily for 10-14 days, can reduce serum digoxin levels by 25% in healthy people. St. John's wort is thought to affect the multidrug transporter, P-glycoprotein, which mediates the absorption and elimination of digoxin and other drugs (382,6473,7808,7810,9204,96552,97171). St. John's wort products providing less than 7.5 mg of hyperforin daily do not appear to affect digoxin levels (97171).
|
St. John's wort reduces the levels and clinical effects of docetaxel.
Details
Clinical research shows that taking a specific St. John's wort product (Hyperiplant, VSM) 300 mg three times daily for 14 days increases docetaxel clearance by about 14%, resulting in decreased plasma concentrations of docetaxel in cancer patients. This is most likely due to induction of cytochrome P450 3A4 (CYP3A4) by St. John's wort (89661).
|
Theoretically, St. John's wort may reduce the levels and clinical effects of fentanyl.
Details
Given that St. John's wort induces cytochrome P450 3A4 (CYP3A4) and P-glycoprotein, it is possible that concomitant use of St. John's wort with fentanyl will reduce plasma levels and analgesic activity of fentanyl (96552). However, some clinical research in healthy adults shows that taking St. John's wort (LI-160, Lichtwer Pharma) 300 mg daily for 21 days does not alter the pharmacokinetics or clinical effects of intravenous fentanyl (102868). It is unclear if these findings can be generalized to oral, intranasal, or transdermal fentanyl.
|
St. John's wort may increase the levels and clinical effects of fexofenadine.
Details
A single dose of St. John's wort decreases the clearance of fexofenadine and increases its plasma levels. However, the effect of St. John's wort on plasma levels of fexofenadine seems to be lost if dosing is continued for more than 2 weeks (9685). Patients taking fexofenadine and St. John's wort concurrently should be monitored for possible fexofenadine toxicity.
|
St. John's wort may reduce the levels and clinical effects of finasteride.
Details
St. John's wort reduces plasma levels of finasteride in healthy male volunteers due to induction of finasteride metabolism via cytochrome P450 3A4 (CYP3A4). The clinical significance of this interaction is not known (96552).
|
St. John's wort may reduce the levels and clinical effects of gliclazide.
Details
Taking St. John's wort decreases the half-life and increases clearance of gliclazide in healthy people (22431).
|
St. John's wort may increase the metabolism and reduce the effectiveness of atorvastatin, lovastatin, and rosuvastatin. However, it does not seem to affect pravastatin, pitavastatin, or fluvastatin.
Details
Concomitant use of St. John's wort can reduce plasma concentrations of the active simvastatin metabolite, simvastatin hydroxy acid, by 28%. St. John's wort induces intestinal and hepatic cytochrome P450 3A4 (CYP3A4) and intestinal P-glycoprotein/MDR-1, a drug transporter. This increases simvastatin clearance. It also increases the clearance of atorvastatin (Lipitor), lovastatin (Mevacor), and rosuvastatin (Crestor). St. John's wort does not seem to affect the plasma concentrations of pravastatin (Pravachol), pitavastatin (Livalo) or fluvastatin (Lescol), which are not substrates of CYP3A4 or P-glycoprotein (10627,96552,97171).
|
St. John's wort reduces the levels and clinical effects of imatinib.
Details
Taking St. John's wort 900 mg daily for 2 weeks reduces the bioavailability and half-life of a single dose of imatinib and decreases its serum levels by 30% in healthy volunteers. This is most likely due to induction of cytochrome P450 3A4 (CYP3A4) by St. John's wort, which increases clearance of imatinib (11888,96552).
|
St. John's wort may reduce the levels and clinical effects of indinavir.
Details
In healthy volunteers, taking St. John's wort concurrently with indinavir reduces plasma concentrations of indinavir by inducing metabolism via cytochrome P450 3A4 (CYP3A4) (96552). Theoretically, this could result in treatment failure and viral resistance.
|
St. John's wort reduces the levels and clinical effects of irinotecan.
Details
St. John's wort 900 mg daily for 18 days decreases serum levels of irinotecan by at least 50%. Clearance of the active metabolite of irinotecan, SN-38, is also increased, resulting in a 42% decrease in the area under the concentration-time curve (9206,97171). This is thought to be due to induction of cytochrome P450 3A4 (CYP3A4) by St. John's wort (7092,96552).
|
St. John's wort might reduce the levels and clinical effects of ivabradine.
Details
Taking St. John's wort 900 mg containing 7.5 mg of hyperforin daily for 14 days with a single dose of ivabradine causes a 62% reduction in plasma levels of ivabradine. This interaction is thought to be due to induction of cytochrome P450 3A4 (CYP3A4) by St. John's wort, increasing the metabolism of ivabradine (96552,97171).
|
St. John's wort reduces the levels and clinical effects of ketamine.
Details
Taking St. John's wort 300 mg three times daily for 14 days can decrease maximum serum levels of ketamine by around 66% and area under the concentration-time curve of ketamine by 58%. This is most likely due to induction of cytochrome P450 3A4 (CYP3A4) by St. John's wort (89663).
|
St. John's wort reduces the levels and clinical effects of mephenytoin.
Details
Preliminary clinical research in healthy males shows that taking St. John's wort for 14 days induces cytochrome P450 2C19 (CYP2C19) and significantly increases metabolism of mephenytoin (Mesantoin). In people with wild-type 2C19, metabolism was almost 4-fold greater in subjects who received St. John's wort compared to placebo. In contrast, patients with 2C19*2/*2 and *2/*3 genotypes did not demonstrate a similar increase in metabolism (17405).
|
St. John's wort might reduce the levels and clinical effects of methadone.
Details
St. John's wort might decrease the effectiveness of methadone by reducing its blood concentrations. In one report, two out of four patients on methadone maintenance therapy for addiction experienced methadone withdrawal symptoms after taking St. John's wort 900 mg daily for a median of 31 days. There was a median decrease in blood methadone concentration of 47% (range: 19% to 60%) when compared to baseline (22419).
|
St. John's wort might reduce the levels and clinical effects of methylphenidate.
Details
St. John's wort might decrease the effectiveness of methylphenidate. In one report, an adult male, stabilized on methylphenidate for attention deficit-hyperactivity disorder (ADHD), experienced increased attention problems and ADHD symptoms after taking St. John's wort 600 mg daily for 4 months. ADHD symptoms improved when St. John's wort was discontinued (15544). The mechanism of this interaction is unknown.
|
St. John's wort decreases the levels and clinical effects of NNRTIs.
Details
St. John's wort increases the oral clearance of nevirapine (Viramune) by 35%. Subtherapeutic concentrations are associated with therapeutic failure, development of viral resistance, and development of drug class resistance. St. John's wort induces intestinal and hepatic cytochrome P450 3A4 (CYP3A4) and intestinal P-glycoprotein/MDR-1, a drug transporter (1290,1340,4837,96552).
|
St. John's wort decreases the levels and clinical effects of omeprazole.
Details
Taking St. John's wort, 300 mg orally three times daily for 14 days, reduces serum concentrations of omeprazole by inducing its metabolism via cytochrome P450 (CYP) 2C19 and 3A4. The reduction of omeprazole serum levels is dependent on CYP2C19 genotype, with reductions up to 50% in extensive metabolizers and 38% in poor metabolizers (22440,96552).
|
St. John's wort decreases the levels and clinical effects of oxycodone.
Details
St. John's wort can increase oxycodone metabolism by inducing cytochrome P450 3A4 (CYP3A4), reducing plasma levels and analgesic activity (96552).
|
St. John's wort decreases the levels and clinical effects of P-glycoprotein substrates.
Details
St. John's wort induces P-glycoprotein. P-glycoprotein is a carrier mechanism responsible for transporting drugs and other substances across cell membranes. When P-glycoprotein is induced in the gastrointestinal (GI) tract, it can prevent the absorption of some medications. In addition, induction of p-glycoprotein can decrease entry of drugs into the central nervous system (CNS) and decrease access to other sites of action (382,1340,7810,11722).
|
St. John's wort decreases the levels and clinical effects of phenobarbital.
Details
St. John's wort may increase the metabolism of phenobarbital. Plasma concentrations of phenobarbital should be monitored carefully. The dose of phenobarbital may need to be increased when St. John's wort is started and decreased when it is stopped (9204).
|
St. John's wort decreases the levels and clinical effects of phenprocoumon.
Details
St. John's wort appears to increase the metabolism of phenprocoumon (an anticoagulant that is not available in the US) by increasing the activity of the cytochrome P450 2C9 (CYP2C9) enzyme. This may result in decreases in the anticoagulant effect and international normalized ratio (INR) (9204).
|
St. John's wort decreases the levels and clinical effects of phenytoin.
Details
St. John's wort may increase the metabolism of phenytoin. Plasma concentrations of phenytoin should be monitored closely. The dose of phenytoin may need to be increased when St. John's wort is started and decreased when it is stopped (9204).
|
Theoretically, St. John's wort might increase the likelihood for photosensitivity reactions when used in combination with photosensitizing drugs.
Details
|
Theoretically, St. John's wort might decrease the levels and clinical effects of procainamide.
Details
Animal research shows that taking St. John's wort extract increases the bioavailability of procainamide, but does not increase its metabolism (14865). Whether this interaction is clinically significant in humans is not known.
|
St. John's wort reduces the levels and clinical effects of PIs.
Details
In healthy volunteers, St. John's wort can reduce the plasma concentrations of indinavir (Crixivan) by inducing cytochrome P450 3A4 (CYP3A4). This might result in treatment failure and viral resistance (1290,7808,96552). St. John's wort also induces P-glycoprotein, which can result in decreased intracellular protease inhibitor concentrations and increased elimination (9204).
|
Theoretically, St. John's wort might decrease the effectiveness of reserpine.
Details
Animal research shows that St. John's wort can antagonize the effects of reserpine (758).
|
St. John's wort decreases the levels and clinical effects of rivaroxaban.
Details
A small pharmacokinetic study in healthy volunteers shows that taking a single dose of rivaroxaban 20 mg after using a specific St. John's wort extract (Jarsin, Vifor SA) 450 mg orally twice daily for 14 days reduces the bioavailability of rivaroxaban by 24% and reduces rivaroxaban's therapeutic inhibition of factor Xa by 20% (104038).
|
Theoretically, St. John's wort might inhibit reuptake and increase levels of serotonin, resulting in additive effects with serotonergic drugs.
Details
|
St. John's wort decreases the levels and clinical effects of tacrolimus.
Details
Taking a St. John's wort extract (Jarsin) 600 mg daily significantly decreases tacrolimus serum levels. Dose increases of 60% may be required to maintain therapeutic tacrolimus levels in patients taking St. John's wort. St. John's wort is thought to lower tacrolimus levels by inducing cytochrome P450 3A4 (CYP3A4) enzymes (7095,10329).
|
St. John's wort might decrease the levels of theophylline, although this effect might not be clinically relevant.
Details
St. John's wort does not seem to significantly affect theophylline pharmacokinetics (11802). There is a single case report of a possible interaction with theophylline. A patient who smoked and was taking 11 other drugs experienced an increase in theophylline levels after discontinuation of St. John's wort. This increase has been attributed to a rebounding of theophylline serum levels after St. John's wort was no longer present to induce metabolism via cytochrome P450 1A2 (CYP1A2) (3556,7808,9204). However, studies in healthy volunteers show that St. John's wort is unlikely to affect theophylline to any clinically significant degree (11802).
|
St. John's wort might decrease the levels and clinical effects of tramadol.
Details
|
St. John's wort might decrease the levels and clinical effects of voriconazole.
Details
Clinical research shows that taking St. John's wort with voriconazole reduces voriconazole exposure and increases voriconazole metabolism by approximately 107%. Voriconazole is primarily metabolized by cytochrome P450 (CYP) 2C19, with CYP3A4 and CYP2C9 also involved (89660). St. John's wort induces CYP2C19, CYP3A4, and CYP2C9 (9204,10830,10847,10848,11889,11890,17405,22423,22424,22425)(22427,48603).
|
St. John's wort decreases the levels and clinical effects of warfarin.
Details
Taking St. John's wort significantly increases clearance of warfarin, including both its R- and S-isomers (11890,15176). This is likely due to induction of cytochrome P450 (CYP) 1A2 and CYP3A4 (11890). St. John's wort can also significantly decrease International Normalized Ratio (INR) in people taking warfarin (1292). In addition, taking warfarin at the same time as St. John's wort might reduce warfarin bioavailability. When a dried extract is mixed with warfarin in an aqueous medium, up to 30% of warfarin is bound to particles, reducing its absorption (10448).
|
St. John's wort might decrease the levels and clinical effects of zolpidem.
Details
|
Theoretically, vitamin B6 might increase the photosensitivity caused by amiodarone.
Details
|
Theoretically, vitamin B6 may have additive effects when used with antihypertensive drugs.
Details
Research in hypertensive rats shows that vitamin B6 can decrease systolic blood pressure (30859,82959,83093). Similarly, clinical research in patients with hypertension shows that taking high doses of vitamin B6 may reduce systolic and diastolic blood pressure, possibly by reducing plasma levels of epinephrine and norepinephrine (83091).
|
Vitamin B6 may increase the metabolism of levodopa when taken alone, but not when taken in conjunction with carbidopa.
Details
Vitamin B6 (pyridoxine) enhances the metabolism of levodopa, reducing its clinical effects. However, this interaction does not occur when carbidopa is used concurrently with levodopa (Sinemet). Therefore, it is not likely to be a problem in most people (3046).
|
High doses of vitamin B6 may reduce the levels and clinical effects of phenobarbital.
Details
|
High doses of vitamin B6 may reduce the levels and clinical effects of phenytoin.
Details
|
Below is general information about the adverse effects of the known ingredients contained in the product St. John's Wort Plus. 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, kava seems to be well tolerated.
Most Common Adverse Effects:
Orally: Drowsiness, dry mouth, dizziness, gastrointestinal upset, headache, memory problems, tremor.
Serious Adverse Effects (Rare):
Orally: There have been over 100 reported cases of hepatotoxicity and a few reported cases of rhabdomyolysis.
Cardiovascular ...Long-term use of very large amounts of kava, especially in high doses (400 mg kava pyrones daily), has been associated with overall poor health including symptoms of low body weight, reduced protein levels, puffy face, hematuria, increased red blood cell volume, decreased platelets and lymphocytes, and possibly pulmonary hypertension (4032,6402). Tachycardia and electrocardiogram (ECG) abnormalities (tall P waves) have been reported in heavy kava users (6402).
Dermatologic ...Orally, kava can cause allergic skin reactions, including sebotropic eruptions, delayed-type hypersensitivity, or urticarial eruption (4032,11370,28489,57277,57325,57343). Chronic use of high doses of kava has also been associated with kava dermopathy, which consists of reddened eyes; dry, scaly, flaky skin; and temporary yellow discoloration of the skin, hair, and nails (6240,6401,8414,8417,11370,28485,57342). This pellagra-like syndrome is unresponsive to niacinamide treatment (6240,7728,11370). The cause is unknown, but may relate to interference with cholesterol metabolism (6240). Kava's adverse effects on liver function might also contribute to kava dermopathy (6401,8417). Kava dermopathy usually occurs within three months to one year of regular kava use, and resolves when the kava dose is decreased or discontinued (6401,8414). Kava dose should be decreased or discontinued if kava dermopathy occurs (6401).
Gastrointestinal ...Orally, kava may cause gastrointestinal upset, nausea, or dry mouth (2093,2094,4032,11370,18316,57228,57343).
Hematologic ...Orally, chronic use of very high doses of kava has been associated with increased red blood cell volume, reduced platelet volume, reduced lymphocyte counts, and reduced serum albumin (6402,57258). Hematuria has also been reported anecdotally (6402).
Hepatic
...Since the early 2000's, hepatotoxicity has been a particular concern with kava.
Worldwide, there have been at least 100 reported cases of hepatotoxicity following use of kava products (7024,7068,7086,7096,11795,17086)(57252,57254,57297). However, some experts question the clinical validity of several of these cases (11369,11371). Some cases were reported multiple times and in some cases it was unlikely that kava was the causative agent (7068,57253).
In susceptible patients, symptoms can show up after as little as 3-4 weeks of kava use. Symptoms include yellowed skin (jaundice), fatigue, and dark urine (7024,7068). Liver function tests can be elevated after 3-8 weeks of use, possibly followed by hepatomegaly and onset of encephalopathy (7024). Kava has also been reported to exacerbate hepatitis in patients with a history of recurrent hepatitis (390). However, in many cases, symptoms seem to resolve spontaneously, and liver function tests usually normalize within eight weeks (390,7068).
Liver toxicity is more frequently associated with prolonged use of very high doses (6401,57346). But there is some concern that even short-term use of kava in typical doses might cause acute hepatitis in some patients, including severe hepatocellular necrosis. The use of kava for as little as 1-3 months has resulted in need for liver transplant and death, although these events are rare (7024,7068,7086,7096,17086).
There is some speculation that the type of extraction method could be responsible for these rare cases of hepatotoxicity (17086). The "Pacific kava paradox" holds that while the alcohol and acetone extracts of kava used for commercial products cause liver toxicity, the traditional kava rhizome preparation mixed with water might not be toxic (11794,17086). However, a more recent analysis reports cases of hepatotoxicity from the aqueous kava extract and suggests that kava's hepatotoxic effects may be due to contaminants such as mold (29676). Other suggested causes of hepatotoxicity include quality of the kava plant, concomitant medications, large doses and prolonged use, and toxic constituents and metabolites of kava (57300,88532).
Some commercial kava extracts contain parts of the stems and other aerial parts in addition to the rhizome, and it has been suggested that a constituent called pipermethysine, which is only found in these aerial parts, might be partly responsible for hepatotoxicity (17086). Other constituents of kava which might contribute to hepatotoxicity are kavalactones, which are metabolized by cytochrome P450 (CYP450) enzymes in the liver. Reactive metabolites are produced which conjugate with glutathione, and might deplete glutathione in a similar manner to acetaminophen (17086). Increased levels of gamma-glutamyl transferase, involved in the production of glutathione, have been reported in chronic kava users (17086). One of the enzymes involved in production of reactive metabolites from kavalactones is cytochrome P450 2E1 (CYP2E1), which is induced by chronic alcohol intake. Alcohol may also compete for other enzymes which clear kavalactone metabolites from the body. This might explain the observation that alcohol ingestion seems to increase the risk of hepatotoxicity with kava (7068,17086).
There is also speculation that "poor metabolizers" or those patients with deficiency in the cytochrome P450 2D6 (CYP2D6) isoenzyme, which occurs in up to 10% of people of European descent, may be at increased risk for hepatotoxic effects from kava (7068). This deficiency has not been found in Pacific Islanders. However, this theory has not been confirmed.
Due to the concerns regarding the potential hepatotoxicity of kava, kava supplements were withdrawn from European and Canadian markets in 2002 (7086). However, many of the market withdrawals of kava have been lifted after re-evaluation of kava suggested that the risk of hepatotoxicity was minimal (91593,91594,91615). Still, clinical practice guidelines from a joint taskforce of the World Federation of Societies of Biological Psychiatry (WFSBP) and the Canadian Network for Mood and Anxiety Treatments (CANMAT) recommend exercising caution when using kava in patients with preexisting liver issues (110318). Until more is known, tell patients to use kava cautiously and recommend liver function tests for routine users or those with underlying liver disease.
Immunologic ...Sjögren syndrome has been associated with an herbal supplement containing kava, echinacea, and St. John's wort. Echinacea may have been the primary cause, because Sjögren syndrome is an autoimmune disorder. The role of kava in this syndrome is unclear (10319).
Musculoskeletal
...Kava has been linked with reports of rhabdomyolysis.
A 34-year-old man who consumed kava tea several times a week developed rhabdomyolysis with a peak creatine kinase level of 32,500 units/liter (18212). However, there is speculation that this might have been due to product impurities rather than kava itself. Another case report describes rhabdomyolysis with myoglobinuria and a creatine kinase level of 100,500 units/liter in a 29-year-old man who had taken kava in combination with guarana and ginkgo biloba (18213).
Cases of ataxia and tremors have been reported in patients taking single doses of kava powder 205 grams (11373).
Neurologic/CNS
...Orally, kava may cause headache, dizziness, and drowsiness (4032,6402,11370,11372,11373,18316,112642).
It might also cause extrapyramidal side effects such as involuntary oral and lingual reflexes, twisting movements of the head and trunk, tremors, and other parkinsonian-like symptoms possibly due to dopamine antagonism (534,4055,7727,8415,102086). In one clinical trial, patients taking a kava supplement providing 120 mg of kavalactones twice daily for 16 weeks had a 3.2-fold greater risk of experiencing tremors when compared with patients taking placebo (102086). Theoretically, kava may worsen symptoms in patients with Parkinson disease or precipitate Parkinson-like symptoms in certain patients (4055,7727). Unlike benzodiazepines, kava is not thought to be associated with impaired cognitive function (2097,2098,11373,57332,57333). However, one clinical trial shows that taking a kava supplement providing 120 mg of kavalactones twice daily for 16 weeks increases the risk for memory impairment by 55% when compared with placebo (102086).
Orally, kava may reduce alertness and impair motor coordination in a dose-dependent manner. Some preliminary reports have noted a decline in accuracy of visual attention and slower reaction times after kava ingestion, particularly at higher doses and in combination with alcohol (11373,95926). Population research has also found that ingesting large amounts of kava tea (typically 50 times higher than what is used medicinally in the US) within a 12-hour period before driving increases the odds of being involved in a serious motor vehicle crash resulting in death or serious injury by almost 5-fold when compared to not drinking kava tea (95927). Use of normal doses of kava may also affect the ability to drive or operate machinery, and driving under the influence (DUI) citations have been issued to individuals observed driving erratically after drinking large amounts of kava tea (535). However, in computer-based driving simulator tests, there are no reported adverse effects of kava on performance (95926). Additionally, other research shows that consuming over 4400 mg of kavalactones over a 6-hour kava session does not seem to impair alertness or attention when compared with non-kava drinkers (103867). Similar research using a specific psychometric tool (Brain Gauge) shows that consuming approximately 3680 mg of kavalactones in a 6-hour kava session seems to impair temporal order judgment, which is associated with the brain's ability to track the order of events, when compared with non-kava drinkers. However, it does not seem to impact cognitive domains related to focus, accuracy, timing perception, plasticity, or fatigue when compared with non-kava drinkers (110435).
Ocular/Otic ...Orally, high doses of kava may cause eye irritation (7728). There is one case report of impaired accommodation and convergence, increased pupil diameter, and oculomotor disturbance following a single dose of kava (9920).
Psychiatric ...Apathy has been associated with traditional use of kava at high doses (57313).
Pulmonary/Respiratory ...Orally, kava may cause shortness of breath, possibly due to pulmonary hypertension (6402).
Renal ...Orally, kava may cause acute urinary retention (57349).
General
...Orally, St.
John's wort is generally well tolerated.
Most Common Adverse Effects:
Orally: Diarrhea, dizziness, dry mouth, gastrointestinal discomfort (mild), fatigue, headache, insomnia, restlessness, and sedation.
Topically: Skin rash and photodermatitis.
Serious Adverse Effects (Rare):
Orally: There have been rare case reports of suicidal ideation and psychosis after taking St. John's wort.
Cardiovascular
...In clinical research, palpitations have been reported for patients taking St.
John's wort orally, although the number of these events was higher for the patients taking sertraline (76070). In one case report, an adult female developed recurrent palpitations and supraventricular tachycardia (SVT) within 3 weeks of initiating St. John's wort 300 mg daily. SVT and related symptoms responded to Valsalva maneuvers and did not recur after discontinuing therapy (106051).
Edema has also been reported in clinical research for some patients treated with St. John's wort 900-1500 mg daily for 8 weeks (10843). Cardiovascular collapse following induction of anesthesia has been reported in an otherwise healthy patient who had been taking St. John's wort for 6 months (8931). A case of St. John's wort-induced hypertension has been reported for a 56-year-old patient who used St. John's wort extract 250 mg twice daily for 5 weeks. Blood pressure normalized after discontinuation of treatment (76073). A case of new-onset orthostatic hypotension and light-headedness has been reported for a 70 year-old homebound patient who was taking multiple prescription medications and herbal products, including St. John's wort (76128). When all herbal products were discontinued, these symptoms improved, and the patient experienced improvement in pain control.
Dermatologic
...Both topical and chronic oral use of St.
John's wort can cause photodermatitis (206,620,758,4628,4631,6477,13156,17986,76072,76148)(95506,110318). The average threshold dose range for an increased risk of photosensitivity appears to be 1.8-4 grams St. John's wort extract or 5-10 mg hypericin, daily. Lower doses might not cause this effect (4542,7808). For example, a single dose of St. John's wort extract 1800 mg (5.4 mg hypericin) followed by 900 mg (2.7 mg hypericin) daily does not seem to produce skin hypericin concentrations thought to be high enough to cause phototoxicity (3900,4542,76266). Females appear to have a higher risk of dose-related photosensitivity. In a dose-ranging, small clinical trial, almost all of the female participants experienced mild to moderate photosensitivity with paresthesia in sun-exposed skin areas after administration of St. John's wort (Jarsin, Casella Med) 1800 mg daily for 3-6 days. Symptoms resolved about 12-16 days after discontinuation (95506). Male participants reported no adverse effects at this dose, and both genders reported no adverse effects at lower doses. Light or fair-skinned people should employ protective measures against direct sunlight when using St. John's wort either topically or orally (628).
Total body erythroderma without exposure to sunlight, accompanied by burning sensation of the skin, has also been reported (8930). Orally, St. John's wort may cause pruritus or skin rash, although these events seem to occur infrequently (76140,76148,76245). A case of persistent scalp and eyebrow hair loss has been reported for a 24-year-old schizophrenic female who was taking olanzapine plus St. John's wort 900 mg/day orally (7811). Also, a case of surgical site irritation has been reported for a patient who applied ointment containing St. John's wort (17225).
Endocrine ...A case of syndrome of inappropriate secretion of antidiuretic hormone (SIADH) in a 67-year-old male with depression has been reported. During a 3-month period, the patient was taking St. John's wort 300 mg daily then increased to 600-900 mg daily with no adverse effects despite a low serum sodium level of 122mEq/L, elevated levels of urine sodium, and urine osmolality suggestive of SIADH. St. John's wort appeared to be the only contributing factor. The patient's sodium level normalized 3 weeks after discontinuation of St. John's wort (95508).
Gastrointestinal ...Orally, St. John's wort may cause dyspepsia, anorexia, diarrhea, nausea, vomiting, and constipation, although these events seems to occur infrequently (4897,13021,17986,76070,76071,76113,76146,76150,76271).
Genitourinary
...Orally, St.
John's wort can cause intermenstrual or abnormal menstrual bleeding (1292,76056). However, this effect has occurred in patients who were also taking an oral contraceptive. Changes in menstrual bleeding might be the result of a drug interaction (1292,76056). Also, St. John's wort has been associated with anorgasmia and frequent urination when used orally (10843,76070).
Sexual dysfunction can occur with St. John's wort, but less frequently than with SSRIs (10843). A case of erectile dysfunction and orgasmic delay has been reported for a 49-year-old male after taking St. John's wort orally for one week. Co-administration of sildenafil 25-50 mg prior to sexual activity reversed the sexual dysfunction. Previously, the patient had experienced orgasmic delay, erectile dysfunction, and inhibited sexual desire when taking a selective serotonin reuptake inhibitor (sertraline) (4836).
Hepatic ...A case of acute hepatitis with prolonged cholestasis and features of vanishing bile duct syndrome has been reported for a patient who used tibolone and St. John's wort orally for 10 weeks (76135). A case of jaundice with transaminitis and hyperbilirubinemia has been reported for a 79 year-old female who used St. John's wort and copaiba (95505). Laboratory values normalized 7 weeks after discontinuation of both products.
Musculoskeletal ...Orally, St. John's wort may cause muscle or joint stiffness, tremor, muscle spasms, or pain, although these events appear to occur rarely (76070).
Neurologic/CNS ...St. John's wort may cause headache, dizziness, fatigue, lethargy, or insomnia (5096,13021,76070,76071,76113,76132,76133,76150,89666). Isolated cases of paresthesia have been reported for patients taking St. John's wort (5073). A case of subacute toxic neuropathy has been reported for a 35-year-old female who took St. John's wort 500 mg daily orally for 4 weeks (621).
Ocular/Otic ...There is concern that taking St. John's wort might increase the risk of cataracts. The hypericin constituent of St. John's wort is photoactive and, in the presence of light, may damage lens proteins, leading to cataracts (1296,17088). In population research, people with cataracts were significantly more likely to have used St. John's wort compared to people without cataracts (17088). Ear and labyrinth disorders have been possibly attributed to use of St. John's wort in clinical research, although these events rarely occur (76120).
Psychiatric
...St.
John's wort can induce hypomania in depressed patients and mania in depressed patients with occult bipolar disorder (325,3524,3555,3568,10845,76047,76064,76137,110318). Cases of first-episode psychosis have been reported for females who used St. John's wort orally. In both cases, symptoms resolved following discontinuation of St. John's wort and treatment with antipsychotics for several weeks (13015,89664). Also, psychosis and delirium have been reported for a 76-year-old female patient who used St. John's wort for 3 weeks. The patient may have been predisposed to this effect due to undiagnosed dementia (76270). Restlessness, insomnia, panic, and anxiety have been noted for some patients taking St. John's wort orally (5073,13156,76070,76132,76268,76269,89665).
In isolated cases, St. John's wort has been associated with a syndrome consisting of extreme anxiety, confusion, nausea, hypertension, and tachycardia. These symptoms may occur within 2-3 weeks after it is started, in patients with no other predisposing factors. This syndrome has been diagnosed as the serotonin syndrome (6201,7811,110318). In one case, the symptoms began after consuming tyramine-containing foods, including aged cheese and red wine (7812). In an isolated case, a 51-year-old female reported having had suicidal and homicidal thoughts for 9 months while taking vitamin C and a St. John's wort extract. Symptoms disappeared within 3 weeks of discontinuing treatment (76111). A case of decreased libido has been reported for a 42-year-old male with mood and anxiety disorders who had taken St. John's wort orally for 9 months (7312).
St. John's wort has been associated with withdrawal effects similar to those found with conventional antidepressants. Headache, nausea, anorexia, dry mouth, thirst, cold chills, weight loss, dizziness, insomnia, paresthesia, confusion, and fatigue have been reported. Withdrawal effects are most likely to occur within two days after discontinuation but can occur one week or more after stopping treatment in some people. Occurrence of withdrawal symptoms may not be related to dose or duration of use (3569,11801).
Pulmonary/Respiratory ...Orally, St. John's wort may cause sore throat, swollen glands, laryngitis, sinus ache, sweating, and hot flashes, although the frequency of these events appears to be similar to placebo (76150).
Renal ...Orally, St. John's wort has been associated with a case report of acute kidney failure in a 46-year-old female after one dose of homemade St. John's wort tea. Three sessions of hemodialysis were required before there was full recovery (106741). However, causality is unclear since the patient had also been taking diclofenac intermittently for a month prior to developing kidney failure.
Other ...Sjogren's syndrome has been reported in a patient taking herbal supplements including St. John's wort, echinacea, and kava. Echinacea may have been the primary cause, because Sjogren's syndrome is an autoimmune disorder. The role of St. John's wort in causing this syndrome is unclear (10319).
General
...Orally or by injection, vitamin B6 is well tolerated in doses less than 100 mg daily.
Most Common Adverse Effects:
Orally or by injection: Abdominal pain, allergic reactions, headache, heartburn, loss of appetite, nausea, somnolence, vomiting.
Serious Adverse Effects (Rare):
Orally or by injection: Sensory neuropathy (high doses).
Dermatologic ...Orally, vitamin B6 (pyridoxine) has been linked to reports of skin and other allergic reactions and photosensitivity (8195,9479,90375). High-dose vitamin B6 (80 mg daily as pyridoxine) and vitamin B12 (20 mcg daily) have been associated with cases of rosacea fulminans characterized by intense erythema with nodules, papules, and pustules. Symptoms may persist for up to 4 months after the supplement is stopped, and may require treatment with systemic corticosteroids and topical therapy (10998).
Gastrointestinal ...Orally or by injection, vitamin B6 (pyridoxine) can cause nausea, vomiting, heartburn, abdominal pain, mild diarrhea, and loss of appetite (8195,9479,16306,83064,83103,107124,107127,107135). In a clinical trial, one patient experienced infectious gastroenteritis that was deemed possibly related to taking vitamin B6 (pyridoxine) orally up to 20 mg/kg daily (90796). One small case-control study has raised concern that long-term dietary vitamin B6 intake in amounts ranging from 3.56-6.59 mg daily can increase the risk of ulcerative colitis (3350).
Hematologic ...Orally or by injection, vitamin B6 (pyridoxine) can cause decreased serum folic acid concentrations (8195,9479). One case of persistent bleeding of unknown origin has been reported in a clinical trial for a patient who used vitamin B6 (pyridoxine) 100 mg twice daily on days 16 to 35 of the menstrual cycle (83103). It is unclear if this effect was due to vitamin B6 intake.
Musculoskeletal ...Orally or by injection, vitamin B6 (pyridoxine) can cause breast soreness or enlargement (8195).
Neurologic/CNS ...Orally or by injection, vitamin B6 (pyridoxine) can cause headache, paresthesia, and somnolence (8195,9479,16306). Vitamin B6 (pyridoxine) can also cause sensory neuropathy, which is related to daily dose and duration of intake. Doses exceeding 1000 mg daily or total doses of 1000 grams or more pose the most risk, although neuropathy can occur with lower daily or total doses as well (8195). The mechanism of the neurotoxicity is unknown, but is thought to occur when the liver's capacity to phosphorylate pyridoxine via the active coenzyme pyridoxal phosphate is exceeded (8204). Some researchers recommend taking vitamin B6 as pyridoxal phosphate to avoid pyridoxine neuropathy, but its safety is unknown (8204). Vitamin B6 (pyridoxine) neuropathy is characterized by numbness and impairment of the sense of position and vibration of the distal limbs, and a gradual progressive sensory ataxia (8196,10439). The syndrome is usually reversible with discontinuation of pyridoxine at the first appearance of neurologic symptoms. Residual symptoms have been reported in patients taking more than 2 grams daily for extended periods (8195,8196). Tell patients daily doses of 100 mg or less are unlikely to cause problems (3094).
Oncologic ...In females, population research has found that a median intake of vitamin B6 1. 63 mg daily is associated with a 3.6-fold increased risk of rectal cancer when compared with a median intake of 1.05 mg daily (83024). A post-hoc subgroup analysis of results from clinical research in adults with a history of recent stroke or ischemic attack suggests that taking folic acid, vitamin B12, and vitamin B6 does not increase cancer risk overall, although it was associated with an increased risk of cancer in patients who also had diabetes (90378). Also, in patients with nasopharyngeal carcinoma, population research has found that consuming at least 8.6 mg daily of supplemental vitamin B6 during treatment was associated with a lower overall survival rate over 5 years, as well as a reduced progression-free survival, when compared with non-users and those with intakes of up to 8.6 mg daily (107134).
