5-HTP (5-Hydroxytryptophan)
5-HTP (5-hydroxytryptophan) is the immediate biochemical precursor to serotonin. Sold in the UK as a food supplement; no authorised UK food-supplement health claims. Serious interaction risk with serotonergic prescription medication — the combination raises the risk of serotonin syndrome. Pregnancy: avoid. Adults with diagnosed depression or anxiety should follow NHS / NICE pathways, not self- supplement. Source transparency (Griffonia seed extract preferred over opaque synthetic / fermentation routes) is the load-bearing quality marker.
Camden Medicals editorial · Last reviewed 12 June 2026 · Next review December 2026
- Cross-checked against
- NHS
- NICE
- BNF
- EFSA
- FSA
Camden's editorial team independently graded each health claim below on the strength of the published evidence — see the grade beside every condition.
- Class
- Amino acid
- Typical daily dose
- Trials have used 100–300 mg of 5-HTP per day in two or three divided doses across 4–12 weeks. UK retail products supply 50–200 mg of 5-HTP per serving. Camden NB-412 supplies up to ~52 mg of 5-HTP per capsule (Griffonia Seed Extract 20:1, 175 mg per capsule, declared <30% 5-HTP), 2–4 capsules daily.
- Top use evidence
- Limited
On this page
What it is
5-HTP (5-hydroxytryptophan) is an amino acid derivative that sits one biochemical step downstream of L-tryptophan and one step upstream of serotonin (5-hydroxytryptamine). The pathway runs: L-tryptophan → 5-HTP → serotonin → (subsequently) melatonin. L-tryptophan is converted to 5-HTP by tryptophan hydroxylase (TPH); 5-HTP is then converted to serotonin by aromatic L-amino acid decarboxylase (AADC). 5-HTP itself is not synthesised in appreciable quantity from dietary protein — it is generated within the body from L-tryptophan as needed.
Unlike serotonin (which cannot cross the blood-brain barrier), 5-HTP crosses freely. Once across, AADC in the brain and periphery converts it to serotonin. This is why 5-HTP is positioned in pharmacology textbooks as a serotonin precursor — the biochemistry is direct. It also means that 5-HTP raises serotonin synthesis upstream of every prescription medication that modulates serotonin handling, which is the basis of the serotonin syndrome interaction warning that runs through this entry.
Commercially, retail 5-HTP arrives via two main routes. The first is Griffonia simplicifolia seed extract — a natural plant source (West African woody climber, Fabaceae family) whose seed coat contains 5-HTP at typically 5–20% by weight. Camden's NB-412 uses this route, supplying Griffonia Seed Extract 20:1 standardised to a declared 5-HTP percentage. The second route is isolated 5-HTP powder from synthetic chemistry or bacterial-fermentation production, filled directly into capsules. Both deliver the same active molecule, but quality and contaminant profile differ substantially by sourcing. Source disclosure is the load-bearing quality marker — see griffonia for the source-plant detail and the historical EMS context.
Regulatory note: 5-HTP from Griffonia seed extract is a lawful UK food supplement. There are no authorised UK food-supplement health claims for 5-HTP. The MHRA has not classified 5-HTP as a medicine in the UK at the time of writing. Some other jurisdictions (Australia, New Zealand) restrict 5-HTP more tightly. Marketing as a "natural antidepressant" or for any mood / sleep / appetite use is not permissible.
At a glance
- The immediate biochemical precursor to serotonin (5-hydroxytryptamine, 5-HT). Crosses the blood-brain barrier; converted to serotonin by aromatic L-amino acid decarboxylase (AADC).
- No UK-authorised food-supplement health claims. Mood / sleep / appetite framing is not permissible on UK labels or PDPs.
- Two main commercial sources: Griffonia simplicifolia seed extract (Camden NB-412) and isolated 5-HTP from synthetic / bacterial-fermentation routes (variable quality history). Source declaration is the load-bearing quality marker.
- Serious interaction risk with serotonergic medication — SSRIs (sertraline, fluoxetine, citalopram, escitalopram, paroxetine), SNRIs (venlafaxine, duloxetine), MAOIs (phenelzine, moclobemide), tramadol, triptans (sumatriptan, etc.), lithium, dextromethorphan, St John's Wort. Talk to your prescriber.
- Historical EMS (eosinophilia-myalgia syndrome) signal traced to contaminated bacterial-fermentation L-tryptophan in 1989, NOT to Griffonia-derived 5-HTP. Modern reputable supply with disclosed CoA + heavy-metal + contaminant screen is the right hygiene.
- Pregnancy, lactation, paediatric: avoid. Diagnosed depression / anxiety / OCD / fibromyalgia / migraine: NHS pathways apply (NICE NG222, CG113, CG31, NG193, CG150).
What people use it for
Adults exploring supplements alongside lifestyle measures, with awareness of regulatory and interaction limits
Small short trials of 5-HTP (typically 100–300 mg/day across 4–12 weeks) have reported various self-reported endpoints around sleep, mood, and appetite. UK food-supplement claims for any of these are not permissible. Anyone considering 5-HTP must screen for serotonergic medication interactions first — talk to a prescriber if you take any prescribed medication. Reassess use at 4–6 weeks.
Some evidenceLimitedAdults with diagnosed depression, anxiety, OCD, fibromyalgia, or migraine considering 5-HTP
5-HTP is not a UK NHS / NICE pathway for any of these conditions. NICE NG222 (depression in adults), CG113 (generalised anxiety / panic), CG31 (OCD / BDD), NG193 (chronic pain, the pathway relevant to fibromyalgia), and CG150 (headaches, including migraine) apply. Self-supplementation in place of formal assessment and management is not appropriate. Talk to your GP. [1,2,3]
Not supportedInsufficientAdults already taking serotonergic prescription medication (SSRI, SNRI, MAOI, tricyclic, atypical antidepressant, tramadol, triptans, lithium, dextromethorphan, St John's Wort)
Do not start 5-HTP without prescriber review. Serotonin syndrome (potentially life-threatening) is the predictable mechanistic risk when serotonergic agents are combined; supplementation in this context is not the appropriate pathway.
Not supportedInsufficientAdults exploring 5-HTP for short-term sleep-onset interest
Small trials of 5-HTP 100–200 mg in the evening have reported modest reductions in self-reported sleep-onset latency. UK NHS pathways for insomnia (sleep hygiene, CBT-I, short-term z-drugs under prescriber oversight) are the recognised routes; 5-HTP is not on those pathways. No authorised UK claim. [5]
Some evidenceLimited
How it works
5-HTP raises serotonin synthesis upstream of the agents that act on serotonin handling — and that mechanism is what makes both its putative effects and its interaction risks plausible. Once across the blood-brain barrier, AADC converts 5-HTP to serotonin in the central nervous system; some peripheral conversion also occurs in the gut and platelets, which contributes to the GI-side-effect profile (nausea, loose stools) that is the most common adverse event in trials.
Carbidopa, a peripheral AADC inhibitor used in Parkinson's therapy, blocks peripheral conversion and was studied as a co-administration to redirect 5-HTP toward central serotonin synthesis. Case reports of dyskinetic effects with the carbidopa + 5-HTP combination, alongside the limited additional benefit, mean this is not a UK retail context — Camden NB-412 carries the Parkinson's-medication interaction warning.
The serotonin-syndrome mechanism is straightforward: any prescription agent that raises synaptic serotonin (SSRIs / SNRIs block reuptake, MAOIs block breakdown, triptans bind 5-HT receptors) will compound 5-HTP's upstream synthesis-raising effect. The clinical syndrome — agitation, confusion, rapid heart rate, fever, sweating, muscle rigidity, in severe cases seizures — is predictable from the mechanism. UK BNF interactions documentation classifies 5-HTP as a serotonergic agent.
Common myths
Myth"5-HTP is a "natural Prozac""
RealityProzac (fluoxetine) is a Prescription-Only SSRI antidepressant with defined pharmacology, dose-response, and prescribing rules. 5-HTP is a serotonin precursor food supplement with modest, inconsistent self-report trial endpoints and no UK-authorised health claim. The "natural Prozac" framing is marketing, not clinical equivalence. [1]
Myth"Higher 5-HTP doses are always better"
RealityDose-response with 5-HTP is not linear and adverse-event rates rise at higher doses (notably GI upset, headache, and rarely dyskinetic side effects when combined with carbidopa). UK retail products typically supply 50–200 mg per serving. Take the lowest effective dose and reassess at 4–6 weeks.
Myth"5-HTP works the same day you take it"
RealityTrial endpoints in the small studies that exist emerge across days to weeks, not the first dose. Acute / single-dose self- report effects in the literature are modest and inconsistent. Marketing implying same-day sleep or mood effects is not supported by trial protocols.
Myth"You can combine 5-HTP with SSRIs / antidepressants for stronger effect"
RealityDo not. Combining serotonergic agents is the mechanistic recipe for serotonin syndrome — agitation, confusion, rapid heart rate, high blood pressure, fever, sweating, muscle rigidity, and in severe cases seizures or death. UK BNF interactions documentation lists 5-HTP as a serotonergic agent. Talk to your prescriber before any combination.
Myth"5-HTP from any source is the same"
RealityBiochemically the molecule is the same, but contaminant profile and quality discipline differ substantially by sourcing. The 1989 EMS outbreak was bacterial-fermentation L-tryptophan, not Griffonia 5-HTP — and that lesson informs why source disclosure (Griffonia seed extract preferred; synthetic / fermentation acceptable with disclosed CoA + contaminant screen) is the load-bearing quality marker. "5-HTP 100 mg" with no source declaration is not a comparable label to "Griffonia Seed Extract 20:1, <30% 5-HTP".
Myth"5-HTP is unsafe because of the 1989 EMS outbreak"
RealityThe 1989 outbreak was traced to L-tryptophan from a single Japanese manufacturer (Showa Denko) using a bacterial- fermentation process, with specific contaminants ("Peak E", "Peak X") identified. Modern Griffonia-derived 5-HTP from reputable suppliers with disclosed CoA, heavy-metal screening, and contaminant screening is not associated with EMS. Source hygiene is the relevant safety lever, not the molecule itself.
Common online questions
Synthesised from the questions UK shoppers most often ask online about 5-HTP (5-Hydroxytryptophan). Each answer is editorial and links to its evidence in the Sources list below.
What is the difference between 5-HTP and Griffonia seed extract?
5-HTP is the active molecule. Griffonia seed extract is one natural source of that molecule — Griffonia simplicifolia seed contains 5-HTP at typically 5–20% by weight. A label reading "Griffonia Seed Extract, standardised to <30% 5-HTP" tells you the source plant AND the active percentage. A label reading "5-HTP 100 mg" without a source declaration tells you the active dose but not the route — the 5-HTP could be from Griffonia, from synthetic chemistry, or from bacterial fermentation. Source disclosure is the load-bearing quality marker. Camden NB-412 uses Griffonia Seed Extract 20:1 with the 5-HTP percentage declared on the label.
Is 5-HTP legal to buy in the UK?
Yes. 5-HTP from Griffonia seed extract is a lawful UK food supplement. There are no authorised UK food-supplement health claims, so retail framing as a mood / sleep / appetite supplement is not permissible. The MHRA has not classified 5-HTP as a medicine in the UK at the time of writing. Some other jurisdictions (Australia, New Zealand) restrict 5-HTP more tightly; check local rules if travelling.
Can I take 5-HTP with my antidepressant?
Talk to your prescriber first — do not self-combine. SSRIs (sertraline, fluoxetine, citalopram, escitalopram, paroxetine), SNRIs (venlafaxine, duloxetine), MAOIs (phenelzine, moclobemide), tricyclic antidepressants, atypicals (mirtazapine, trazodone), tramadol, triptans, lithium, dextromethorphan, and St John''s Wort all act on serotonin handling. Adding 5-HTP raises serotonin synthesis upstream and can produce serotonin syndrome — a potentially life-threatening condition. Disclose any supplement to your prescribing GP or pharmacist before adding.
What dose of 5-HTP is "normal"?
Trials have used 100–300 mg of 5-HTP per day, in two or three divided doses, across 4–12 weeks. UK retail products typically supply 50–200 mg of 5-HTP per serving. Camden NB-412 supplies up to ~52 mg of 5-HTP per capsule with a 2–4 capsule daily range. There is no UK consensus dose because there is no UK-authorised health claim — the dose ranges are descriptive of trial conditions only. Start at the lower end and reassess at 4–6 weeks.
Is 5-HTP a "natural antidepressant"?
No. 5-HTP is not a UK-licensed antidepressant and is not on UK NHS / NICE pathways for depression. The "natural antidepressant" framing is marketing language, not clinical equivalence. UK NICE NG222 lists the licensed pharmacological and psychological options for depression management. Self- supplementation in place of licensed treatment for diagnosed depression is not appropriate; talk to your GP. [1]
Is the EMS contamination story still relevant?
The 1989 EMS outbreak was traced to L-tryptophan from one Japanese manufacturer using a bacterial-fermentation process, with specific contaminants ("Peak E", "Peak X") identified as the cause. Modern Griffonia-derived 5-HTP from reputable suppliers with disclosed CoA, heavy-metal screening, and contaminant screening is not associated with EMS. The historical signal is what supports the consumer-hygiene framing — source disclosure, declared 5-HTP percentage, CoA on request, contaminant screening — that runs through this entry. The molecule itself is not the issue; opaque sourcing is.
Can I take 5-HTP while pregnant or breastfeeding?
No. Standard advice is to avoid 5-HTP in pregnancy and lactation. There is no human pregnancy or lactation safety data, and the maternal-fetal serotonin axis is well- characterised as sensitive. The Camden NB-412 label carries this contraindication. If you are trying to conceive, talk to your GP before using.
🔬 Camden’s evidence review
The research Camden reviewed, graded on its strength. This is our own appraisal — it sits beneath the official guidance above, never above it.
Self-reported low mood — short-term
LimitedEvidencelimitedOlder small trials of 5-HTP 100–300 mg/day across 4–6 weeks have reported reductions in self-reported low-mood scale scores in some populations. Trials are small, dated, and often used active- comparator (not always placebo) designs. UK NICE NG222 lists NHS pathways for depression management; 5-HTP is not on those pathways. No authorised UK food-supplement claim. [1]
Sleep-onset latency — short-term
LimitedEvidencelimitedSmall trials of 5-HTP 100–200 mg in the evening have reported modest reductions in self-reported sleep-onset latency in some populations. The NHS insomnia pathway leads with sleep hygiene and cognitive-behavioural therapy for insomnia (CBT-I), with short-term hypnotic use under prescriber oversight where appropriate. 5-HTP is not on UK NICE pathways for insomnia. [5]
Appetite regulation in overweight / obesity — short-term
LimitedEvidencelimitedSmall trials of 5-HTP 200–900 mg/day have reported reductions in self-reported appetite scores and modest changes in body weight. Trial sizes are small, durations short, and meta- analytic conclusions are limited. NICE NG246 (overweight and obesity management) lists NHS pathways; 5-HTP is not a recognised pathway and no authorised UK food-supplement weight-management claim applies. [8]
Migraine prophylaxis (historical literature)
LimitedEvidencelimitedOlder trials in migraine prophylaxis reported some reductions in headache frequency / intensity. UK NICE CG150 lists first- line migraine prophylaxis options (propranolol, topiramate); 5-HTP is not among them. Self-supplementation for migraine is not the recognised UK pathway. [3]
Eosinophilia-myalgia syndrome (EMS) — historical safety signal
MixedEvidencemixedIn 1989 a multi-state outbreak of EMS in the United States was traced to L-tryptophan supplements (not 5-HTP) made by a single Japanese manufacturer (Showa Denko) using a bacterial- fermentation process. Subsequent investigation identified contaminants ("Peak E", "Peak X") in the affected batches as the most likely cause. Some 1990s case reports surfaced for 5-HTP supplements with similar contaminant signals. Modern Griffonia-derived 5-HTP from reputable suppliers with disclosed CoA and contaminant screening is not associated with EMS, but the historical signal informs the consumer- hygiene framing around source disclosure and contaminant screening.
Combination with serotonergic medication — interaction risk
MixedEvidencemixedSerotonin syndrome (a potentially life-threatening condition of serotonergic over-stimulation) has been reported in case reports when 5-HTP was combined with SSRIs, SNRIs, MAOIs, tramadol, triptans, lithium, St John''s Wort, dextromethorphan, and other serotonergic agents. The biological plausibility is direct — 5-HTP raises serotonin synthesis upstream of the agents modulating serotonin handling. UK BNF interactions documentation supports the conservative position of not combining without prescriber oversight.
Safety
5-HTP is generally well-tolerated in healthy adults at standard supplement doses for short durations. Serious interaction risk with serotonergic prescription medication — talk to your prescriber. Pregnancy, lactation, paediatric use: avoid. Adults with diagnosed depression or anxiety should follow NHS / NICE pathways, not self-supplement.
Talk to your pharmacist or GP first if you:
- You take any antidepressant — SSRI (sertraline, fluoxetine, citalopram, escitalopram, paroxetine, fluvoxamine), SNRI (venlafaxine, duloxetine), MAOI (phenelzine, isocarboxazid, tranylcypromine, moclobemide), tricyclic, or atypical (mirtazapine, trazodone). Risk of serotonin syndrome.
- You take tramadol, methadone, fentanyl, or pethidine — risk of serotonin syndrome with tramadol; opioid sedation may compound 5-HTP drowsiness.
- You take triptans (sumatriptan, zolmitriptan, rizatriptan, almotriptan, eletriptan, frovatriptan, naratriptan) for migraine — risk of serotonin syndrome.
- You take lithium — risk of serotonin syndrome.
- You take dextromethorphan (over-the-counter cough medicines) — risk of serotonin syndrome.
- You take St John's Wort — risk of serotonin syndrome.
- You take carbidopa or any Parkinson's medication — case reports of dyskinetic effects when carbidopa is combined with 5-HTP.
- You take any sedative, hypnotic, or anxiolytic — possible additive CNS effects.
- You are pregnant, breastfeeding, or trying to conceive — avoid.
- You are under 18 — avoid.
- You have a diagnosis of depression, anxiety, OCD, fibromyalgia, or migraine — talk to your GP; UK NHS / NICE pathways apply.
Common side effects: GI complaints (nausea, abdominal discomfort, loose stools, decreased appetite) are the most common; substantially reduced by lower starting dose. Headache and drowsiness can also occur.
Pregnancy and breastfeeding
Pregnancy: avoid. No human pregnancy safety data; the maternal-fetal serotonin axis is well-characterised as sensitive to disruption.
Lactation: avoid. No human lactation safety data.
Talk to your GP, midwife, or pharmacist before starting any supplement during pregnancy or breastfeeding.
More clinical detail (for clinicians and informed readers)
Contraindications
- Pregnancy — avoid (no human safety data; serotonin axis is sensitive).
- Lactation — avoid.
- Paediatric use — avoid.
- Active SSRI / SNRI / MAOI / tricyclic / atypical antidepressant therapy — avoid combination without prescriber oversight.
- Active triptan / tramadol / lithium / dextromethorphan / St John's Wort use — avoid combination.
- Active Parkinson's disease therapy with carbidopa — avoid combination (dyskinetic-effect case reports).
- History of serotonin syndrome from any cause.
- Active or recurrent mania / hypomania.
Drug interactions
- SSRIs (sertraline, fluoxetine, citalopram, escitalopram, paroxetine, fluvoxamine) — risk of serotonin syndrome.
- SNRIs (venlafaxine, duloxetine) — risk of serotonin syndrome.
- MAOIs (phenelzine, isocarboxazid, tranylcypromine, moclobemide) — risk of serotonin syndrome; avoid.
- Tricyclic antidepressants (amitriptyline, dosulepin, lofepramine) — possible additive serotonergic effects; talk to prescriber.
- Atypical antidepressants (mirtazapine, trazodone) — possible additive serotonergic effects.
- Tramadol, methadone, fentanyl, pethidine — serotonergic activity at clinical doses; risk of serotonin syndrome.
- Triptans (sumatriptan, zolmitriptan, rizatriptan, almotriptan, eletriptan, frovatriptan, naratriptan) — serotonergic activity; risk of serotonin syndrome.
- Lithium — risk of serotonin syndrome.
- Dextromethorphan (over-the-counter cough medicine) — serotonergic activity; risk of serotonin syndrome.
- St John's Wort (Hypericum perforatum) — serotonergic activity; risk of serotonin syndrome.
- Carbidopa — case reports of dyskinetic effects when combined with 5-HTP.
- Sedatives, hypnotics, anxiolytics — possible additive CNS effects.
This is not an exhaustive list. Always tell your prescriber and pharmacist about every supplement you take.
Common side effects
- GI complaints — nausea, abdominal discomfort, loose stools, decreased appetite. Substantially reduced by starting at the lower end of the dose range.
- Headache.
- Drowsiness — particularly at higher doses or evening dosing.
Rare side effects
- Allergic reactions — uncommon.
- Dyskinetic effects — case reports in literature, particularly when 5-HTP is combined with carbidopa.
- Hypomanic / activation symptoms in vulnerable individuals — case reports.
- Serotonin syndrome — when combined with serotonergic medication; potentially life-threatening, requires emergency medical attention.
How to take it
- Typical supplemental range
- Trials have used 100–300 mg of 5-HTP per day in two or three divided doses across 4–12 weeks. UK retail products supply 50–200 mg of 5-HTP per serving. Camden NB-412 supplies up to ~52 mg of 5-HTP per capsule (Griffonia Seed Extract 20:1, 175 mg per capsule, declared <30% 5-HTP), 2–4 capsules daily.
- Timing
- Either on an empty stomach or with a carbohydrate-only snack to avoid amino-acid competition for blood-brain-barrier transport. Evening dosing is the most common pattern in sleep-context literature.
How to spot quality
Look for
- Source declaration on the label — Griffonia simplicifolia seed extract preferred. Synthetic / bacterial-fermentation acceptable only with disclosed CoA + contaminant screen.
- 5-HTP percentage declared on the label (e.g. "<30% 5-HTP" — Camden NB-412 declares this) when supplied as Griffonia extract.
- Country of cultivation declared for Griffonia-sourced material (Ghana, Côte d'Ivoire, Togo are the principal origins).
- CoA available on request, with batch number and issue date.
- Heavy-metal screening + contaminant screening disclosed (informed by the 1989 EMS lesson).
- GMP-certified manufacture; reputable supplier chain.
- Pregnancy contraindication printed on the label.
- Serotonergic-medication interaction warning printed on the label (SSRIs, SNRIs, MAOIs, tramadol, triptans, lithium, dextromethorphan, St John's Wort).
- Lowest effective starting dose — typically 50 mg per serving — with dose-response guidance.
Red flags
- No source declaration — "5-HTP 100 mg" with no Griffonia / synthetic / fermentation disclosure.
- No 5-HTP percentage declared on Griffonia-extract products (extract ratio alone is not a comparable marker).
- No country-of-origin disclosure; opaque Chinese-only supply chain without CoA.
- No heavy-metal or contaminant screening disclosed.
- "Natural antidepressant", "natural Prozac", "depression remedy", or "anxiety cure" framing.
- Sleep / mood / appetite / weight-loss claims (no authorised UK food-supplement claim for 5-HTP).
- No serotonergic-medication interaction warning.
- No pregnancy contraindication.
- Paediatric marketing or formulation.
- High-dose tablets (>300 mg of 5-HTP per serving) without dose-tapering guidance.
Where Camden lands · meets the bar
Camden has one 5-HTP SKU — NB-412 5HTP from Griffonia Seed 90 Capsules. The active is sourced via Griffonia Seed Extract 20:1 at 175 mg per capsule, declared <30% 5-HTP (up to ~52 mg 5-HTP per capsule). Source and standardisation are declared on the label. The label carries the pregnancy contraindication and the SSRI / antidepressant interaction warning. Camden makes no mood / sleep / appetite claims on the PDP — the framing is on the source plant and the precursor-of-serotonin biochemistry only. Heavy-metal and contaminant screening sit on the recommended-documents list for the SKU; CoA is archived per batch.
Commonly combined with
Other ingredients that share a biological pathway, cofactor relationship, or evidence-backed protocol with this one. Mechanisms below cite primary physiology — not folk pairing. Doses are literature ranges, not recommendations. Talk to your pharmacist or GP before changing your stack, especially if you take prescription medication.
Vitamin B6
Limited evidenceVitamin B6 (pyridoxal-5-phosphate) is the cofactor for the AADC enzyme that converts 5-HTP to serotonin. Co-supplementation is mechanistically rational and frequently appears in sleep- or mood-cluster products. UK food-supplement claims for the combination are not authorised.
Aromatic L-amino acid decarboxylase (AADC) — the enzyme that converts 5-HTP to serotonin — uses pyridoxal-5-phosphate (the bioactive form of vitamin B6) as a cofactor. In healthy adults with adequate B6 status this is not rate-limiting; in B6- deficient individuals (rare in the UK general population) adding B6 might in principle support the conversion. Commercial 5-HTP + B6 stacks operate on this rationale.
Evidence: Co-supplementation is mechanistically rational; trial-level evidence for the combination outperforming 5-HTP alone is limited. Both ingredients individually have small short-trial bodies of evidence in their own right.
Doses studied: 5-HTP 50–200 mg + vitamin B6 10–25 mg per serving in commercial sleep-cluster formulations.
Magnesium
Limited evidenceMagnesium frequently appears alongside 5-HTP in sleep-cluster commercial products. The pairing rests on independent sleep-related framing for each ingredient (5-HTP via serotonin precursor; magnesium via NMDA receptor modulation and the EFSA Article 13.1 nervous-system claim). Co-supplementation is not a UK-authorised co-claim.
Magnesium contributes to normal nervous-system function (EFSA Article 13.1 authorised claim) and modulates NMDA glutamate receptors, with downstream sleep-quality framing in some literature. 5-HTP is the upstream serotonin precursor with separate sleep-onset framing. The combination is mechanistically additive in narrative terms but not in UK-authorised claim terms.
Evidence: Both ingredients independently have small sleep-context trial literature. The combination has not been the subject of pivotal UK trials. UK food-supplement claims for the combination are not authorised.
Doses studied: 5-HTP 50–100 mg + magnesium glycinate 200–400 mg evening dose in commercial sleep-cluster products.
L-Tryptophan
Insufficient evidenceL-tryptophan is the upstream precursor (tryptophan → 5-HTP → serotonin pathway). Combining the two is not a standard pattern — it is a duplicative supplementation choice. Where 5-HTP is the chosen route, L-tryptophan adds little; where L-tryptophan is the chosen route (different historical regulatory and EMS context), 5-HTP duplicates the same target.
L-tryptophan is converted to 5-HTP by tryptophan hydroxylase (TPH); 5-HTP is then converted to serotonin by AADC. Both pathways converge on the same serotonin-synthesis endpoint. The 1989 EMS contamination episode attached to L-tryptophan supplements (Showa Denko bacterial fermentation), not to Griffonia 5-HTP — the regulatory and consumer-hygiene conversation is therefore different for the two.
Evidence: No clinical evidence supporting the combination over either ingredient alone. The historical EMS context attaches to L-tryptophan; modern Griffonia 5-HTP is not associated.
Doses studied: Not a typical commercial combination. Where L-tryptophan is supplemented, dose is 500–1000 mg evening; where 5-HTP is supplemented, dose is 50–200 mg evening.
St John's Wort (Hypericum perforatum)
Mixed evidenceDO NOT COMBINE. St John's Wort (Hypericum perforatum) is itself serotonergic — combining with 5-HTP raises the risk of serotonin syndrome. This entry exists to flag the pairing as contraindicated, not to recommend it.
St John''s Wort modulates serotonin reuptake and has weak MAOI-like activity. 5-HTP raises serotonin synthesis upstream. The combination is mechanistically the recipe for serotonin syndrome; UK BNF interactions documentation lists both as serotonergic agents. The combination is also not consistent with the do_not_combine cluster routinely listed alongside 5-HTP supplementation.
Evidence: Case reports and pharmacology textbooks support the contraindication. No trials would ethically test the combination.
Doses studied: Should not be combined.