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Complementary and Alternative Medicine - Cam

Search Health Information    5-HTP

5-HTP

Uses

5-hydroxytryptophan is used by the human body to make serotonin, an important substance for normal nerve and brain function. Serotonin appears to play significant roles in sleep, emotional moods, pain control, inflammation, intestinal peristalsis, and other body functions.1

What Are Star Ratings?

Our proprietary “Star-Rating” system was developed to help you easily understand the amount of scientific support behind each supplement in relation to a specific health condition. While there is no way to predict whether a vitamin, mineral, or herb will successfully treat or prevent associated health conditions, our unique ratings tell you how well these supplements are understood by the medical community, and whether studies have found them to be effective for other people.

For over a decade, our team has combed through thousands of research articles published in reputable journals. To help you make educated decisions, and to better understand controversial or confusing supplements, our medical experts have digested the science into these three easy-to-follow ratings. We hope this provides you with a helpful resource to make informed decisions towards your health and well-being.

3 Stars Reliable and relatively consistent scientific data showing a substantial health benefit.

2 Stars Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit.

1 Star For an herb, supported by traditional use but minimal or no scientific evidence. For a supplement, little scientific support.

This supplement has been used in connection with the following health conditions:

Used for Why
2 Stars
Depression
Consult a qualified healthcare practitioner
Depression has been linked to serotonin imbalances in the brain. Supplementing with 5-HTP may increase serotonin synthesis and reduce symptoms.

Disruptions in emotional well-being, including depression, have been linked to serotonin imbalances in the brain.2 Supplementing with 5-HTP (5-hydroxytryptophan) may increase serotonin synthesis. Some trials using 5-HTP with people suffering from depression have shown sign of efficacy.3 , 4 , 5 , 6 , 7 However, much of the research was either uncontrolled or used 5-HTP in combination with antidepressant drugs. One double-blind trial found that 5-HTP was as effective as, or nearly as effective as, an antidepressant drug (fluoxetine).8 Depressed people interested in considering this serotonin precursor should consult a doctor.

2 Stars
Fibromyalgia
100 mg three times per day
Supplementing with 5-HTP may ease symptoms.

People with fibromyalgia often have low serotonin levels in their blood.9 , 10 , 11 Supplementation with 5-HTP may increase serotonin synthesis in these cases. Both preliminary12 , 13 and double-blind trials14 have reported that 5-HTP supplementation (100 mg three times per day) relieves some symptoms of fibromyalgia.

2 Stars
Insomnia
Adults: 200 mg two hours before bedtime and 400 mg at bedtime; children: 3 mg per 2.2 lbs (1 kg) body weight
5-HTP is converted into serotonin and might, therefore, be helpful for insomnia. In one study, supplementing with 5-HTP appeared to improve sleep quality.
The amino acid L-tryptophan has been used successfully for people with insomnia,15 presumably because it is converted to the chemical messenger, serotonin. According to one preliminary trial, L-tryptophan supplementation was 100% effective at promoting sleep in people who awaken between three to six times per night, but not effective at all for people who only awaken once or twice, nor in people who doze on and off throughout the night in a state blurred between sleep and wakefulness.16

A related compound that occurs naturally in the body, 5-HTP (5-hydroxytryptophan), is also converted into serotonin and might, therefore, be helpful for insomnia. In a double-blind trial of people without insomnia, supplementation with 5-HTP (200 mg at 9:15 p.m. and 400 mg at 11:15 p.m.) increased rapid-eye-movement (REM) sleep, presumably indicating improved sleep quality.17 In a preliminary trial of people with fibromyalgia , supplementing with 100 mg of 5-HTP three times a day improved sleep quality.18 However, additional research is needed to determine whether 5-HTP is safe and effective for people with insomnia.

In a preliminary study, 5-HTP was also found to be an effective treatment for "sleep terrors,"19 a common problem in children that causes sudden awakening with persistent fear or terror, screaming, sweating, confusion, and increased heart rate.

2 Stars
Migraine Headache
200 to 600 mg daily for adults, 20 mg for every 10 pounds of body weight for children
Several studies have found 5-HTP to be effective at reducing the frequency, severity, and duration of migraine headaches.

The cause of migraine headache is believed to be related to abnormal serotonin function in blood vessels,20 and 5-HTP (5-hydroxytryptophan, which is converted by the body into serotonin) may affect this abnormality. In one study, 40 people with recurrent migraines received either 5-HTP (200 mg per day) or methysergide (a drug used to prevent migraines) for 40 days. Both compounds reduced the frequency of migraines by about 50%.21 Larger amounts of 5-HTP (600 mg per day) were also found to be as effective as medications for reducing migraine headache attacks in adults in two double-blind trials.22 , 23 Migraine attacks were reduced in frequency, severity, and duration in 90% of those taking 400 mg per day of 5-HTP in a double-blind placebo-controlled trial,24 though another trial found no benefit of 5-HTP.25 In another controlled study, 400 mg of dl-5-HTP (another form of 5-HTP) led to reduced consumption of pain-killing drugs and pain scores after one to two months.26 Children who suffered from migraines and had problems sleeping responded well to a daily amount of 5-HTP equal to 20 mg for every 10 pounds of body weight in a controlled trial,27 though an earlier study showed 5-HTP had no better effect than placebo for children with migraines.28

2 Stars
Obesity
Take under medical supervision: 600 to 900 mg daily for no more than 12 weeks
5-HTP has been shown to reduce appetite and to promote weight loss.
5-HTP (5-hydroxytryptophan), the precursor to the chemical messenger (neurotransmitter) serotonin, has been shown in three short-term controlled trials to reduce appetite and to promote weight loss. In one of these trials (a 12-week double-blind trial), overweight women who took 600 to 900 mg of 5-HTP per day lost significantly more weight than did women who received a placebo. In a double-blind trial with no dietary restrictions, obese people with type 2(non-insulin-dependent) who took 750 mg per dayof 5-HTP for two weeks significantly reduced their carbohydrate and fat intake. Average weight loss in two weeks was 4.6 pounds, compared with 0.2 pounds in the placebo group. This amount has not been established as a safe long-term treatment and should not be tried without a doctor’s supervision; people taking antidepressants or other medications should be aware of potential drug interactions.
2 Stars
Sleep Disturbances
Refer to label instructions
5-HTP is used by the human body to make serotonin, an important substance for normal nerve and brain function. Serotonin appears to play significant roles in sleep.
5-HTP is used by the human body to make serotonin, an important substance for normal nerve and brain function. Serotonin appears to play significant roles in sleep, emotional moods, pain control, inflammation, intestinal peristalsis, and other body functions.29 Insomnia has been associated with tryptophan deficiency in the tissues of the brain;30 therefore, 5-HTP may provide a remedy for this condition.

In a controlled trial, 5-HTP (300 mg per day) was shown to be effective in reducing many symptoms of fibromyalgia, including pain, morning stiffness, sleep disturbances, and anxiety.31 For insomnia, a single 100-mg nighttime dose of 5-HTP was sufficient to improve the duration and depth of sleep in one placebo-controlled trial.32
2 Stars
Tension Headache
Adults: 300 mg daily; children: 100 mg daily
Taking the supplement 5-hydroxytryptophan may lessen headache frequency and limit the need for pain-relieving medications.

5-HTP (5-hydroxytryptophan) may be helpful for tension-type headaches. A recent double-blind study of adults with chronic tension-type headaches found 300 mg per day of 5-HTP reduced the number of headache days by 36%, but this was not significantly different from the 29% reduction in the placebo group.33 (Headaches often improve significantly even when an inactive [placebo] treatment is given).34 Headache severity was also similarly reduced by either 5-HTP or placebo. In this study, 5-HTP was significantly superior to placebo only in reducing the need for pain-relieving medications during headaches. Previous double-blind research studied 5-HTP in groups of patients suffering from many different types of headache, including some with tension-type headaches. Results from these studies also found substantial, but nonsignificant benefits of 5-HTP compared with placebo using either 400 mg per day in adults35 or 100 mg per day in children.36

1 Star
Bipolar Disorder
Refer to label instructions
Supplementing with 5-HTP has had antidepressant effects in people with bipolar disorder; the effect was greater when combined with an antidepressant drug (doctor's supervision recommended)

L-tryptophan is the amino acid used by the body to produce serotonin, a chemical messenger important for proper brain function. Supplementation with L-tryptophan has led to improvement in depression in many studies,37 , 38 but information is limited about its effect on bipolar disorder. Case reports on two bipolar patients treated with lithium or an antidepressant drug described marked improvements when they were given 12 grams daily of L-tryptophan.39 , 40 Two trials using 6 grams of L-tryptophan daily for acute mania in patients with bipolar disorder found little or no improvement,41 , 42 but another double-blind, controlled study using 9.6 grams daily reported better results.43

L-tryptophan is converted to 5-HTP (5-hydroxytryptophan) before it becomes serotonin in the body. In a controlled trial, 200 mg daily of supplemental 5-HTP had antidepressant effects in bipolar patients, though it was not as effective as lithium.44 In a double-blind trial, patients with bipolar disorder had greater improvement with a combination of 5-HTP at 300 mg daily plus an antidepressant drug than with 5-HTP alone.45

1 Star
Eating Disorders
Refer to label instructions
5-HTP has been shown to reduce appetite in weight-control and diabetes trials. However, what effect 5-HTP has on people with eating disorders is unknown

A serotonin precursor, 5-HTP (5-hydroxytryptophan), has been shown to reduce appetite in weight-control and diabetes trials.46 , 47 , 48 However, what effect 5-HTP has, if any, on people with binge eating disorder, bulimia, or anorexia is unknown. Unlike L-tryptophan, 5-HTP is available from health food stores and some pharmacies without prescription.

1 Star
Seasonal Affective Disorder
900 mg a day of a standardized extract
The supplement 5-Hydroxytryptophan increases serotonin production and has shown antidepressant activity. It may be useful in the treatment of SAD.

5-HTP is a substance that increases serotonin production and has shown antidepressant activity.49 It may also be useful in the treatment of SAD, but there is currently no research testing this possibility.

How It Works

How to Use It

In a controlled trial, 5-HTP (300 mg per day) was shown to be effective in reducing many symptoms of fibromyalgia , including pain , morning stiffness, sleep disturbances, and anxiety .50

For depression , 300 mg per day is often effective, though much of the research used 5-HTP in combination with drugs or was uncontrolled.51 , 52 , 53 For insomnia , a single 100-mg nighttime dose of 5-HTP was sufficient to improve the duration and depth of sleep in one placebo-controlled trial.54 For migraine headaches , amounts ranging from 400–600 mg per day have been shown to be effective at reducing the frequency and severity of attacks in most clinical trials.55 , 56 , 57 , 58 , 59 For tension headaches , 100 mg of 5-HTP taken three times per day led to a significant decrease in consumption of pain-relievers, but no significant change in headache duration or intensity.60

Appetite reduction and weight loss (averaging 11 pounds in 12 weeks) has occurred with amounts of 600–900 mg daily.61 , 62 In another clinical trial, 750 mg per day has been shown to be effective at decreasing carbohydrate and fat intake, and promoting weight loss.63

Where to Find It

5-HTP is not present in significant amounts in a typical diet. The human body manufactures 5-HTP from L-tryptophan, a natural amino acid found in most dietary proteins. However, eating food that contains L-tryptophan does not significantly increase 5-HTP levels. Supplemental 5-HTP is naturally derived from the seeds of Griffonia simplicifolia, a West African medicinal plant.

Possible Deficiencies

Disruptions in emotional well-being, including depression and anxiety , have been linked to serotonin imbalances in the brain.64 People with fibromyalgia often have low serotonin levels in their blood.65 , 66 , 67 Supplements of 5-HTP may increase serotonin synthesis in these cases. The cause of migraine headaches is related to abnormal serotonin function in blood vessels,68 and 5-HTP may help correct this abnormality.69 therefore, 5-HTP may provide a remedy for this condition.

Interactions

Interactions with Supplements, Foods, & Other Compounds

5-HTP should not be taken with antidepressants, weight-control drugs, other serotonin-modifying agents, or substances known to cause liver damage, because in these cases 5-HTP may have excessive effects. People with liver disease may not be able to regulate 5-HTP adequately and those suffering from autoimmune diseases such as scleroderma may be more sensitive than others, to 5-HTP.70 These people should not take 5-HTP without consulting a knowledgeable healthcare professional. The safety of taking 5-HTP during pregnancy and breast-feeding is not known at this time.

Interactions with Medicines

Certain medicines interact with this supplement.

Types of interactions: Beneficial Adverse Check

Replenish Depleted Nutrients

  • none

Reduce Side Effects

  • none

Support Medicine

  • Selegiline

    Both L-tryptophan and 5-HTP have been used to treat depression . One controlled study showed that taking selegiline at the same time as 5-HTP enhanced the antidepressant effect when compared with 5-HTP alone.71 Further research is needed to determine whether taking selegiline and 5-HTP together might result in unwanted side effects.

Reduces Effectiveness

  • none

Potential Negative Interaction

  • Citalopram

    Citalopram increases serotonin activity in the brain. 5-HTP and L-tryptophan are converted to serotonin in the brain, and taking either of these compounds with citalopram may increase citalopram-induced side effects. Dietary supplements of L-tryptophan (available only by prescription from special compounding pharmacists) taken with paroxetine (a drug that has similar actions as citalopram) caused headache, sweating, dizziness, agitation, restlessness, nausea, vomiting, and other symptoms.72

    Some doctors have used small amounts of L-tryptophan in combination with SSRIs, to increase their effectiveness. However, because of the potential for side effects, 5-HTP and L-tryptophan should never be taken in combination with citalopram or other SSRIs, unless a doctor is closely monitoring the combination. Foods rich in L-tryptophan do not appear to interact with citalopram or other SSRIs.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Escitalopram

    Escitalopram increases serotonin activity in the brain. 5-HTP and L-tryptophan are converted to serotonin in the brain, and taking either of these compounds with escitalopram may increase escitalopram-induced side effects. Dietary supplements of L-tryptophan (available only by prescription from special compounding pharmacists) taken with paroxetine (a drug that has similar actions as escitalopram) caused headache, sweating, dizziness, agitation, restlessness, nausea, vomiting, and other symptoms.73

    Some doctors have used small amounts of L-tryptophan in combination with SSRIs, to increase their effectiveness. However, because of the potential for side effects, 5-HTP and L-tryptophan should never be taken in combination with escitalopram or other SSRIs, unless a doctor is closely monitoring the combination. Foods rich in L-tryptophan do not appear to interact with escitalopram or other SSRIs.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Fluoxetine

    Fluoxetine works by increasing serotonin activity in the brain. 5-HTP is converted to serotonin in the brain, and taking it with fluoxetine may increase fluoxetine-induced side effects. Until more is known, 5-HTP should not be taken with any SSRI drug, including fluoxetine.

  • Fluvoxamine

    Fluvoxamine works by increasing serotonin activity in the brain. 5-HTP (5-Hydroxytryptophan) and L-tryptophan are converted to serotonin in the brain, and taking them with fluvoxamine may increase fluvoxamine-induced side effects. Until more is known, 5-HTP and L-tryptophan should not be taken with any SSRI drug, including fluvoxamine.

  • Paroxetine

    Paroxetine increases serotonin activity in the brain. 5-HTP and L-tryptophan are converted to serotonin in the brain, and taking either of these compounds with paroxetine may increase paroxetine-induced side effects. Dietary supplements of L-tryptophan (available only by prescriptions from special compounding pharmacists) taken with paroxetine caused headache, sweating, dizziness, agitation, restlessness, nausea, vomiting, and other symptoms.74 Some doctors have used small amounts of L-tryptophan in combination with SSRIs, to increase the effectiveness of the latter. However, because of the potential for side effects, 5-HTP and L-tryptophan should never be taken in combination with paroxetine or other SSRIs, unless the combination is being closely monitored by a doctor. Foods rich in L-tryptophan do not appear to interact with paroxtine or other SSRIs.

    On the other hand, the combination of 45 mg DL-tryptophan (a synthetic variation of L-tryptophan) per pound of body weight (a relatively high dose) with zimelidine, a drug with a similar action to paroxetine, did not cause these side effects in another trial.75

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Sertraline

    Sertraline increases serotonin activity in the brain. 5-HTP and L-tryptophan are converted to serotonin in the brain, and taking either of these compounds with sertraline may increase sertraline-induced side effects.

    In one report, dietary supplements of L-tryptophan (available only by prescriptions from special compounding pharmacists) taken with paroxetine (a drug similar to sertraline) caused headache, sweating, dizziness, agitation, restlessness, nausea, vomiting, and other symptoms.76 On the other hand, the combination of 45 mg DL-tryptophan (a synthetic variation of L-tryptophan) per pound of body weight (a relatively high dose) with zimelidine, a drug with a similar action to sertraline, did not cause these side effects in another trial.77 Some doctors have used small amounts of L-tryptophan in combination with SSRIs, to increase the effectiveness of the latter. However, because of the potential for side effects, 5-HTP and L-tryptophan should never be taken in combination with sertraline or other SSRIs, unless the combination is being closely monitored by a doctor. Foods rich in L-tryptophan do not appear to interact with sertraline or other SSRIs.

  • Sibutramine

    The amino acids L-tryptophan and 5-hydroxytryptophan (5-HTP) are occasionally used to treat mental depression . Taking sibutramine with L-tryptophan or 5-HTP might result in a rare, but serious group of symptoms known as “serotonin syndrome.”78 Symptoms associated with serotonin syndrome may include confusion, anxiety, muscle weakness, incoordination, and vomiting. Therefore, individuals taking sibutramine should avoid supplementing with L-tryptophan and 5-HTP.

  • Tramadol

    Tramadol, which blocks serotonin reuptake in the brain, has been associated with two cases of serotonin syndrome.79 , 80 5-HTP and L-tryptophan are converted to serotonin in the brain. While no interactions have yet been reported with tramadol and 5-HTP or L-tryptophan, taking 5-HTP or L-tryptophan with tramadol may increase the risk of tramadol-induced side effects, including serotonin syndrome.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Venlafaxine

    Venlafaxine, a potent serotonin reuptake inhibitor, has been associated with several cases of serotonin syndrome.81 , 82 , 83 , 84 5-HTP and L-tryptophan are converted to serotonin in the brain, and taking them with venlafaxine may increase venlafaxine-induced side effects. While no interactions with venlafaxine and 5-HTP or L-tryptophan have been reported, until more is known, people taking venlafaxine are cautioned to avoid 5-HTP or L-tryptophan.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Zolpidem

    Nine cases of zolpidem-induced hallucinations associated with serotonin reuptake inhibiting antidepressants have been reported, some lasting for several hours.85 5-HTP and L-tryptophan are converted to serotonin in the brain, and taking them with zolpidem may increase zolpidem-induced hallucinations, though no interactions have yet been reported with zolpidem and 5-HTP or L-tryptophan.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

Explanation Required

  • Almotriptan

    Triptans work by stimulating serotonin receptors in the brain. 5-HTP (5-Hydroxytryptophan) and L-tryptophan are converted to serotonin in the brain, and taking them with eletriptan could increase eletriptan-induced side effects. However, no interactions have yet been reported with eletriptan and 5-HTP or L-tryptophan.

  • Carbidopa

    5-HTP and carbidopa have been reported to improve intention myoclonus (a neuromuscular disorder) in some human cases but not others.86 , 87 , 88 Several cases of scleroderma-like illness have been reported in patients using carbidopa and 5-HTP for intention myoclonus.89 , 90 , 91

  • Carbidopa-Levodopa

    Several cases of scleroderma-like illness have been reported in patients using carbidopa and 5-HTP (5-Hydroxytryptophan).92 , 93 , 94 People taking carbidopa should not supplement 5-HTP without consulting the prescribing physician.

  • Eletriptan

    Eletriptan works by stimulating serotonin receptors in the brain. 5-HTP (5-Hydroxytryptophan) and L-tryptophan are converted to serotonin in the brain, and taking them with eletriptan could increase eletriptan-induced side effects. However, no interactions have yet been reported with eletriptan and 5-HTP or L-tryptophan.

  • Frovatriptan

    Triptans work by stimulating serotonin receptors in the brain. 5-HTP (5-Hydroxytryptophan) and L-tryptophan are converted to serotonin in the brain, and taking them at the same time as 5-HT1 agonists could increase unwanted side effects. However, at the time of this writing there are no known interactions with 5-HT1 agonists and 5-HTP or L-tryptophan.95

  • Naratriptan

    Triptans work by stimulating serotonin receptors in the brain. 5-HTP (5-Hydroxytryptophan) and L-tryptophan are converted to serotonin in the brain, and taking them at the same time as 5-HT1 agonists could increase unwanted side effects. However, at the time of this writing there are no known interactions with 5-HT1 agonists and 5-HTP or L-tryptophan.96

  • Rizatriptan

    Triptans work by stimulating serotonin receptors in the brain. 5-HTP (5-Hydroxytryptophan) and L-tryptophan are converted to serotonin in the brain, and taking them at the same time as 5-HT1 agonists could increase unwanted side effects. However, at the time of this writing there are no known interactions with 5-HT1 agonists and 5-HTP or L-tryptophan.97

  • Sumatriptan

    Sumatriptan works by stimulating serotonin receptors in the brain. 5-HTP (5-Hydroxytryptophan) and L-tryptophan are converted to serotonin in the brain, and taking them with sumatriptan could increase sumatriptan-induced side effects. However, no interactions have yet been reported with sumatriptan and 5-HTP or L-tryptophan.

  • Zolmitriptan

    Zolmitriptan works by stimulating serotonin receptors in the brain. 5-HTP (5-Hydroxytryptophan) and L-tryptophan are converted to serotonin in the brain, and taking them with zolmitriptan could increase zolmitriptan-induced side effects. However, no interactions have yet been reported with zolmitriptan and 5-HTP or L-tryptophan.

The Drug-Nutrient Interactions table may not include every possible interaction. Taking medicines with meals, on an empty stomach, or with alcohol may influence their effects. For details, refer to the manufacturers’ package information as these are not covered in this table. If you take medications, always discuss the potential risks and benefits of adding a supplement with your doctor or pharmacist.

Side Effects

Side Effects

During the clinical trials described above, some people taking large amounts of 5-HTP experienced gastrointestinal upset (e.g. nausea) or, less often, headache, sleepiness, muscle pain, or anxiety .

A substance known as “Peak X” has been found in low concentrations in several over-the-counter 5-HTP preparations. Some researchers think this substance may be linked98 , 99 , 100 to toxicity previously reported101 , 102 , 103 in a 1989 L-tryptophan contamination incident. However, there is serious question about whether Peak X is actually the toxic agent and it may be unrelated to the problems previously associated with L-tryptophan.104 , 105 , 106 , 107 , 108 , 109 , 110 , 111 Although two articles reported possible associations between 5-HTP consumption and toxicity symptoms similar to those attributed to contaminated L-tryprophan,112 , 113 evidence linking 5-HTP or Peak X with any toxicity symptoms remains speculative. Although the structure of Peak X has recently been identified, there is no firm evidence that this substance has caused or contributed to any toxicity or disease.114

Very high intakes of 5-HTP have caused muscle jerks in guinea pigs115 and both muscle jerks116 and diarrhea in mice.117 Injected 5-HTP has also caused kidney damage in rats.118 To date, these problems have not been reported in humans. “Serotonin syndrome,” a serious but uncommon condition caused by excessive amounts of serotonin, has not been reported to result from supplementation with 5-HTP; in theory it could be triggered by the supplement.119 However, the level of intake at which this toxic effect might potentially occur remains unknown.

References

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4. Angst J, Woggon B, Schoepf J. The treatment of depression with L-5-hydroxytryptophan versus imipramine. Results of two open and one double-blind study. Arch Psychiatr Nervenkr 1977;224:175-86.

5. Nolen WA, van de Putte JJ, Dijken WA, et al. Treatment strategy in depression. II. MAO inhibitors in depression resistant to cyclic antidepressants: two controlled crossover studies with tranylcypromine versus L-5-hydroxytryptophan and nimifensine. Acta Psychiatr Scand 1988;78:676-83.

6. Nolen WA, van de Putte JJ, Dijken WA, Kamp JS. L-5-HTP in depression resistant to re-uptake inhibitors. An open comparative study with tranylcypromine. Br J Psychiatry 1985;147:16-22.

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8. Jangid P, Malik P, Singh P, et al. Comparative study of efficacy of L-5-hydroxytryptophan and fluoxetine in patients presenting with first depressive episode. Asian J Psychiatr 2013;6:29–34.))

9. Fava M, Rosenbaum JF, MacLaughlin R, et al. Neuroendocrine effects of S-adenosyl-L-methionine, a novel putative antidepressant. J Psychiatr Res 1990;24:177-84.

10. Bell KM, Potkin SG, Carreon D, Plon L. S-adenosylmethionine blood levels in major depression: changes with drug treatment. Acta Neurol Scand 1994;154(suppl):15-8.

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12. Puttini PS, Caruso I. Primary fibromyalgia syndrome and 5-hydroxy-L-tryptophan: a 90-day open study. J Int Med Res 1992;20:182-9.

13. Moldofsky H, Warsh JJ. Plasma tryptophan and musculoskeletal pain in non-articular rheumatism (“fibrositis syndrome”). Pain 1978;5:65-71.

14. Caruso I, Sarzi Puttini P, Cazzola M, Azzolini V. Double-blind study of 5-hydroxytryptophan versus placebo in the treatment of primary fibromyalgia syndrome. J Int Med Res 1990;18:201-9.

15. Schneider-Helmert D, Spinweber CL. Evaluation of L-tryptophan for treatment of insomnia: A review. Psychopharmacology (Berlin) 1986;89(1):1-7.

16. Lindsley JG, Hartmann EL, Mitchell W. Selectivity in response to L-tryptophan among insomniac subjects: a preliminary report. Sleep 1983;6:247-56.

17. Wyatt RJ, Zarcone V, Engelman K, et al. Effects of 5-hydroxytryptophan on the sleep of normal human subjects. Electroencephalogr Clin Neurophysiol 1971;30:505-9.

18. Puttini PS, Caruso I. Primary fibromyalgia syndrome and 5-hydroxy-L-tryptophan: a 90-day open study. J Int Med Res 1992;20:182-9.

19. Bruni O, Ferri R, Miano S, Verrillo E. L-5-Hydroxytryptophan treatment of sleep terrors in children. Eur J Pediatr 2004;163:402-7.

20. Kimball RW, Friedman AP, Vallejo E. Effect of serotonin in migraine patients. Neurology 1960;10:107-11.

21. Sicuteri F. The ingestion of serotonin precursors (L-5-hydroxytryptophan and L-tryptophan) improves migraine headache. Headache 1973;13:19-22.

22. Titus F, Davalos A, Alom J, Codina A. 5-hydroxytryptophan versus methysergide in the prophylaxis of migraine. Eur Neurol 1986;25:327-9.

23. Maissen CP, Ludin HP. Comparison of the effect of 5-hydroxytryptophan and propranolol in the interval treatment of migraine. Schweizerische Medizinische Wochenschrift /Journal Suisse de Medecine 1991;121:1585-90 [in German].

24. De Benedittis G, Massei R. 5-HT precursors in migraine prophylaxis: A double-blind cross-over study with L-5-hydroxytryptophan versus placebo. Clin J Pain 1986;3:123-9.

25. Mathew NT. 5-hydroxytryptophan in the prophylaxis of migraine. Headache 1978;18:111-3.

26. Bono G, Criscuoli M, Martignoni E, et al. Serotonin precursors in migraine prophylaxis. Advances in Neurology 1982;33:357-63.

27. De Giorgis G, Miletto R, Iannuccelli M, et al. Headache in association with sleep disorders in children: A psychodiagnostic evaluation and controlled clinical study ñ L-5-HTP versus placebo. Drugs Exp Clin Res 1987;13:425-33.

28. Santucci M, Cortelli P, Rossi PG, et al. L-5-Hydroxytryptophan versus placebo in childhood migraine prophylaxis: a double-blind crossover study. Cephalalgia 1986;6:155-7.

29. Guyton AC, Hall JE. Textbook of Medical Physiology, 9th ed. Philadelphia: W. B. Saunders, 1996.

30. Schneider-Helmert D, Spinweber CL. Evaluation of L-tryptophan for treatment of insomnia: A review. Psychopharmacology (Berlin) 1986;89(1):1-7.

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