5-HTP: Benefits, Side Effects, Weight Loss Evidence and Drug Interactions

5-HTP (5-hydroxytryptophan) is a compound your body makes from the amino acid tryptophan on the way to serotonin, and supplements are usually extracted from the seeds of the African shrub Griffonia simplicifolia. The evidence behind it is thin: three small Italian trials from 1989 to 1998 reported less eating and some weight loss, and reviews of mood studies rate the research as low quality. The main safety concern is serotonin syndrome when 5-HTP is combined with antidepressants or other serotonin-raising drugs. This guide covers what 5-HTP does, what studies found, its side effects and who should avoid it.

Peptide Labs sells two combination supplements that list 5-HTP, and we mention them below. This article is general information, not medical advice.

What is 5-HTP?

Your body turns tryptophan, an amino acid found in protein foods, into 5-HTP and then into serotonin, a chemical messenger involved in mood, appetite and sleep. Serotonin is later used to make melatonin. Memorial Sloan Kettering Cancer Center (MSKCC) notes that the main commercial source of 5-HTP is Griffonia simplicifolia seed. Supplements are sold on the idea that supplying the step after tryptophan raises serotonin. How much that happens in the brain after a capsule, and whether it changes anything you would notice, is the part research has not settled.

In the US, 5-HTP is sold as a dietary supplement, so it does not go through FDA review for safety or effectiveness before sale. It also gets extra scrutiny because it became popular after L-tryptophan supplements were pulled from the market in 1989, a story covered in the safety section below.

5 HTP benefits: what the research shows

Most marketing claims fall into a few areas. MSKCC’s summary is a fair snapshot: early findings for appetite and fibromyalgia, inconclusive results for depression, few sleep studies and no benefit found for migraines or tension headaches.

5-HTP for weight loss

The appetite research comes mainly from one group at La Sapienza University in Rome. In a 1989 crossover study, 19 women with obesity took 5-HTP or placebo for five weeks without a prescribed diet; while on 5-HTP they ate less and lost weight. A 1992 double-blind trial in 20 adults with obesity ran for two six-week periods and reported weight loss, lower carbohydrate intake and early fullness. A 1998 trial enrolled 25 overweight adults with type 2 diabetes for two weeks; 20 finished, and the 5-HTP group ate fewer calories and lost weight.

These results are interesting but weak by current standards. The trials were tiny and short, they came from the same team, and they used far larger daily amounts than combination supplements usually list. No large independent trial has confirmed them, and we found no studies of the multi-ingredient “GLP-1” formulas that now include 5-HTP. For a wider look at appetite products, see our appetite suppressants guide. Saffron, which often sits next to 5-HTP in these blends, has its own evidence summary in our saffron supplement guide.

5-HTP and mood

A Cochrane systematic review of 5-HTP and tryptophan for depression located 108 trials but judged only two, with 64 patients in total, good enough to include. Those two favored the supplements over placebo, yet the reviewers said the evidence was of insufficient quality to be conclusive and that, because proven antidepressants exist, the clinical usefulness of 5-HTP is limited. A 2020 meta-analysis in Nutrition Reviews included 13 studies and described the research as relatively weak, noting that few studies had placebo groups.

Depression is a medical condition. Anyone with symptoms should talk to a clinician rather than pick a supplement, and no one should stop a prescribed antidepressant to try 5-HTP.

5-HTP side effects

MSKCC lists digestive symptoms as the most common: nausea, vomiting and diarrhea. Less common effects include headache, trouble sleeping and palpitations, and there are case reports of mania, serotonin syndrome and a scleroderma-like illness. The Natural Medicines monograph republished by RxList adds heartburn, stomach pain, drowsiness, sexual problems and muscle problems, and links very large daily amounts to severe stomach problems and muscle spasms.

Serotonin syndrome and drug interactions

Serotonin syndrome happens when serotonin activity builds up too far. One hospital health library describes it as a dangerous condition with mental changes, hot flashes, rapidly fluctuating blood pressure and heart rate, and possibly coma. The risk comes mainly from stacking 5-HTP with medicines that also raise serotonin:

• Antidepressants, including SSRIs such as sertraline, fluoxetine and escitalopram, and tricyclics. Natural Medicines rates this a major interaction.
• MAO inhibitors such as phenelzine, plus the antibiotic linezolid, which MSKCC also lists.
• Pain medicines tramadol, meperidine and pentazocine.
• Dextromethorphan, the cough suppressant in many cold products.
• Triptans for migraine, such as sumatriptan and rizatriptan.
• Carbidopa for Parkinson’s disease; the combination has been linked to a scleroderma-like illness.
• St. John’s wort and SAMe, supplements that also affect serotonin.
• Sedatives, because 5-HTP may add to drowsiness.

The eosinophilia-myalgia syndrome question

In 1989 an outbreak of eosinophilia-myalgia syndrome (EMS), a disorder with severe muscle pain and high counts of a type of white blood cell, affected more than 1,500 people and caused 37 deaths, according to the National Organization for Rare Disorders (NORD). It was traced to contaminated L-tryptophan from a single manufacturer, L-tryptophan supplements were withdrawn, and 5-HTP filled the gap.

Whether 5-HTP carries a similar risk is disputed. In 1994, FDA scientists described a family who became ill after taking 5-HTP; their product contained an impurity not found in other samples. In 1999, Mayo Clinic researchers reported that all eight commercial 5-HTP samples they tested contained contaminants from the “peak X” family linked to EMS cases. A 2004 review by authors from a testing laboratory argued that there were no definitive toxicity cases and questioned the peak X findings. NORD says the isolated EMS cases diagnosed today are attributed to L-tryptophan or 5-HTP supplements, and the Cochrane reviewers also flagged the question as unresolved. Choosing brands that publish third-party testing is sensible, but testing cannot settle a question the science has not.

Who should avoid 5-HTP or ask first

• Anyone taking an antidepressant or another serotonin-raising medicine from the list above.
• Pregnant or breastfeeding people: there is not enough reliable safety information, and Natural Medicines advises avoiding it.
• People scheduled for surgery: RxList advises stopping at least 2 weeks before, because some drugs used during surgery also affect serotonin.
• Anyone under 18: the Atrafen label says to consult a healthcare professional first, and Night Shred is labeled for adults only.
• People with a history of mania or bipolar disorder should talk to their clinician, given case reports of mania.

Products at Peptide Labs that contain 5-HTP

In our catalog, 5-HTP appears inside multi-ingredient appetite formulas rather than on its own. Here is what the labels say:

• ColonBroom GLP-1 Booster: 100 mg of 5-HTP per 2 capsules with chromium picolinate, berberine, saffron extract and licorice. The listing advises asking a healthcare professional before use if you take medication, including antidepressants, or are pregnant or nursing.
• Atrafen GLP Ultra: 5-HTP inside a 280 mg blend with alpha-lipoic acid and green tea, so the 5-HTP amount is not disclosed. The label says to talk to your doctor before use if you take antidepressants or other serotonergic medication.

InnoSupps Night Shred combines 5-HTP and L-tryptophan with 3 mg of melatonin and KSM-66 ashwagandha, and some stimulant formulas hide 5-HTP inside a proprietary blend. Despite the names, none of these products is a GLP-1 medication; our explainer on GLP-1 support supplements explains the difference. Our cortisol belly guide covers ashwagandha, and our chromium picolinate guide covers another common ingredient in these blends.

Frequently Asked Questions

Questions about a label? Contact us or read our Buyer’s Guide. Follow the label and ask a healthcare provider before starting any supplement, especially if you take medicines. These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

Last reviewed September 2026.

Related guides: Appetite Suppressants: Prescription Drugs, Natural Options and the Risks, Saffron Supplement Guide: Extract Types, Standardization and What Studies Measured, Cortisol Belly: Stress, Belly Fat and What Cortisol Supplements Show.