5-HTP by Lidtke

POSSIBLY EFFECTIVE

• Depression. Oral 5-HTP seems to improve symptoms of depression. Details: A meta-analysis of preliminary clinical research shows that taking 5-HTP for up to 8 weeks might improve symptoms of depression in some patients. The pooled remission rate across 13 studies was 65%, and the pooled effect size across 7 studies assessing the change in depressive symptom scores from baseline was large (102854). In most studies, the dose of 5-HTP administered ranged from 150-800 mg daily, although doses as high as 3 grams daily have been used (903,30000,30125,30138,102854). Some research has compared 5-HTP to conventional antidepressants. In one clinical trial of adults experiencing a first episode of depression, taking 5-HTP orally, titrated up to a daily dose of 400 mg, decreased depression symptoms similarly to fluoxetine titrated up to 40 mg daily (30112). Limited research also suggests that taking 5-HTP 300-800 mg daily seems to work similarly to fluvoxamine 50 mg (2203) or imipramine 150 mg daily (30125). Adding 5-HTP 300 mg orally daily to clomipramine 50 mg daily for 28 days has also been shown to reduce depressive symptoms when compared with clomipramine alone (6245).

POSSIBLY INEFFECTIVE

• Down syndrome. Oral 5-HTP does not seem to improve muscle tone or cognitive skills in patients with this condition. Details: Although early reports suggested that 5-HTP might improve muscle tone and activity levels in infants with Down syndrome (88172), other research has shown no benefit. One small clinical study suggests that taking 5-HTP 0.5-5 mg/kg daily orally from early infancy until 3-4 years of age does not improve muscle tone or developmental ability scores in children with Down syndrome when compared with a control group (88173). Also, a prospective, double-blind study shows that taking 5-HTP 1-2 mg/kg daily orally, alone or with pyridoxine 5-10 mg/kg daily orally, beginning at birth and continuing until 3 years of age, does not improve muscle tone or development of cognitive, social, or language skills when compared with placebo (30153).

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Alcohol use disorder. Oral 5-HTP has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research shows that taking a food supplement containing 5-HTP 5 mg, phenylalanine 300 mg, and glutamine 150 mg daily for 40 days during alcohol detoxification therapy reduces withdrawal symptoms when compared with alcohol detoxification therapy alone (30100). However, taking a combination of 5-HTP 25-100 mg with carbidopa 25 mg four times daily for one year does not seem to improve alcohol abstinence rates when compared with placebo (30007). The effect of 5-HTP alone is unclear.
• Alzheimer disease. Although there has been interest in using oral 5-HTP for Alzheimer disease, there is insufficient reliable information about the clinical effects of 5-HTP for this condition.
• Anxiety. It is unclear if oral 5-HTP is beneficial in patients with anxiety disorders. Details: A small clinical study in people with anxiety disorders shows that taking 5-HTP 25-150 mg daily with carbidopa 150 mg daily for 8 weeks reduces anxiety when compared with baseline, but not when compared with clomipramine 25-150 mg daily (30124).
• Attention deficit-hyperactivity disorder (ADHD). Although there is interest in using oral 5-HTP for ADHD, there is insufficient reliable information about the clinical effects of 5-HTP for this condition.
• Cerebellar ataxia. It is unclear if oral 5-HTP reduces cerebellar ataxia symptoms. Details: One small clinical trial in people with cerebellar ataxia of various etiologies shows taking 5-HTP orally 10 mg/kg daily for 4 months improve quantitative ataxia scores when compared with placebo. Further improvement was noted in subjects continuing treatment for another 8 months (916). However, in a subsequent trial in this population, taking 5-HTP orally 1 gram daily for 10 months did not improve symptom scores when compared with placebo (30164). Also, a small clinical study in people with Friedreich's ataxia shows that taking 5-HTP 200-300 mg daily for 1 month, then 600-900 mg daily for 5 months (depending on body weight), does not improve symptoms when compared with placebo (30165).
• Fibromyalgia. Small clinical studies suggest that oral 5-HTP may improve symptoms of primary fibromyalgia syndrome. Details: Small clinical studies in people with primary fibromyalgia syndrome suggest that taking 5-HTP 100 mg orally three times daily for 30-90 days might improve pain, tenderness, sleep, anxiety, fatigue, and morning stiffness when compared with baseline or placebo (913,10286).
• Inflammatory bowel disease (IBD). It is unclear if oral 5-HTP is beneficial for IBD. Details: Preliminary clinical research in adults with stable IBD and fatigue shows that taking a specific 5-HTP (Levotonine, Panpharma) 100 mg orally twice daily for 8 weeks does not improve fatigue scores when compared with placebo. However, the validity of this study is limited by high patient drop-out (111311).
• Menopausal symptoms. It is unclear if oral 5-HTP is beneficial for symptoms of menopause. Details: A small clinical study in postmenopausal patients shows that taking 5-HTP orally 50 mg three times daily for 4 weeks does not reduce hot flash frequency when compared with placebo (30061).
• Migraine headache. It is unclear if oral 5-HTP reduces frequency of migraines. Details: Preliminary clinical research shows that taking 5-HTP 600 mg daily decreases migraine attack frequency similarly to methysergide 3 mg daily (30129). However, other small clinical studies show that taking 5-HTP 400 mg daily does not reduce the frequency or severity of migraine attacks when compared with placebo (30130,30184). Also, in children 6-12 years of age, one very small clinical study shows that taking 5-HTP 5 mg/kg daily in 3 divided doses for 12 weeks does not reduce the frequency or severity of migraine attacks when compared with placebo (30128).
• Obesity. It is unclear if oral 5-HTP is beneficial in for weight loss. Details: Some very small clinical studies show that taking 5-HTP orally, 300 mg three times daily 30 minutes before meals for 2-12 weeks, improves early satiety and decreases daily caloric intake in females with obesity when compared with placebo (914,30018). 5-HTP was also associated with a mean weight loss of 1.7 kg over 6 weeks when caloric intake was not restricted, and a mean weight loss of 3.3 kg over 6 weeks when caloric intake was restricted to about 1200 calories daily (914,30114). In moderately overweight adults with type 2 diabetes, taking 5-HTP 250 mg three times daily 30 minutes before meals for 2 weeks reduces caloric intake by about 22% and decreases body weight by about 2 kg when compared to baseline (30175).
• Obsessive-compulsive disorder (OCD). It is unclear if oral 5-HTP is beneficial in patients with OCD. Details: A small clinical study in patients with moderate to severe OCD shows that adding 5-HTP 200 mg orally daily to fluoxetine, titrated up to 60 mg daily, for 12 weeks reduces symptom severity when compared with placebo and fluoxetine. A complete response, defined as greater than or equal to 35% improvement in overall Yale-Brown Obsessive Compulsive Scale (Y-BOCS) score, was seen in 54% of those taking 5-HTP at week 12, compared with only 12% of those taking placebo (104250). These results were not observed until week 12, which indicates that a longer treatment period may be needed to see the full effects of the intervention.
• Opioid withdrawal. Oral 5-HTP has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research in Chinese males undergoing detoxification for heroin addiction shows that taking 5-HTP 200 mg orally daily for 6 days, in combination with tyrosine, phosphatidylcholine, and L-glutamine, might reduce insomnia and withdrawal symptoms and improve mood when compared with a control group (88178).
• Panic disorder. It is unclear if intravenous 5-HTP is beneficial for reducing anxiety in panic disorder. Details: A small clinical trial in females with panic disorders shows that receiving an intravenous (IV) infusion of 5-HTP, 60 mg over 30 minutes after premedication with carbidopa 100 mg orally, does not appear to reduce anxiety when compared with control (30093).
• Parkinson disease. It is unclear if oral 5-HTP is beneficial for improving Parkinson disease symptoms. Details: Two preliminary clinical trials show that taking 5-HTP 50 mg daily for 1 month seems to improve levodopa-induced dyskinesia and symptoms of depression, but not motor functioning or apathy, when compared with placebo in patients with Parkinson disease (102853,104251). Both studies used a crossover design to correct for the small sample size, but may still have been inadequately powered to detect small changes in these outcomes. However, in another study, taking larger doses of 5-HTP, 275-1500 mg orally daily along with carbidopa 150-1000 mg daily for up to 38 days, worsened rigidity, bradykinesia, and functional disability (30140). Other research has evaluated 5-HTP in patients with Parkinson disease and REM sleep behavior disorder (RBD). A small crossover study in these patients shows taking oral 5-HTP 50 mg daily for 4 weeks does not improve the percentage of REM sleep without atonia or the frequency of RBD events when compared with baseline or placebo. Patients taking 5-HTP report modest improvements in part II (motor function; e.g. swallowing, walking, and dressing) of the Unified Parkinson Disease Rating Scale (UPDRS), but not other parts of the UPDRS, when compared with placebo (107793). This study may have been inadequately powered to detect a difference between groups.
• Premenstrual syndrome (PMS). Although there is interest in using oral 5-HTP for PMS, there is insufficient reliable information about the clinical effects of 5-HTP for this condition.
• Seizures. Although there is interest in using oral 5-HTP for seizures, there is insufficient reliable information about the clinical effects of 5-HTP for this condition.
• Tension headache. It is unclear if oral 5-HTP reduces tension headache severity. Details: A small clinical study in adults with a history of chronic tension headaches suggests that taking 5-HTP 100 mg three times daily for 8 weeks does not reduce pain intensity or the number of days with headache when compared with placebo (2204).
• Tinnitus. Oral 5-HTP has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Research has evaluated a specific capsule formulation (Tinnitan Duo; Laboratorios Salvat) containing 5-HTP, ginkgo extract, magnesium, melatonin, pantothenic acid, vitamin B6, and zinc at undeclared doses. A small clinical trial in patients with subjective tinnitus shows taking this product as one capsule twice daily for 3 months improves Tinnitus Handicap Inventory (THI) total score and THI emotional subscale score at 3 months when compared with baseline. Patients also report improvement in tinnitus-related distress (107792). The validity of this study is limited by the lack of randomization and placebo-control; additionally, it is unclear if any effects are due to 5-HTP, other ingredients, or the combination. More evidence is needed to rate 5-HTP for these uses.

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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).

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CARBIDOPA (Lodosyn) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D 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).

CNS DEPRESSANTS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, concomitant use of 5-HTP with medications that cause sedation might have additive effects.  Details In clinical trials, 5-HTP has been associated with drowsiness and somnolence (914,30093,30129,30130).

SEROTONERGIC DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Combining serotonergic drugs with 5-HTP might cause additive serotonergic effects.  Details 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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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).

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