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Amino acid (serotonin precursor) Pregnancy: §4.6 VERBATIM: 'No clinical data on exposed pregnancies are available. Animal studies do not indicate direct or indirect harmful effects with respect to pregnancy, embryonal/fetal development, parturition or postnatal development (see section 5.3). Caution should be exercised when prescribing to pregnant women. Due to the absence of any clinical data relating to the use of Optimax in nursing mothers, Optimax should not be taken during breast feeding. No data relating to fertility are available for Optimax.' Note that the SPC advises caution in pregnancy rather than contraindicating it, and contraindicates breast-feeding only in the sense of 'should not be taken'.

Tryptophan

Brand names: Optimax

Tryptophan is an amino acid precursor of serotonin used as an adjunctive treatment in resistant depression, typically under specialist supervision.

Adult dose

Dose: Two 500 mg capsules (1 g L-tryptophan) three times daily — 3 g daily in total.
Route: Oral — §4.2 verbatim: 'For oral use.'
Frequency: Three times daily
Max: Up to 6 g L-tryptophan daily — §4.2 verbatim: 'for some patients, up to 6g L-tryptophan may be required.'
SCOPE — this is the whole of the adult posology in the fetched UK SPC; the product has a single oral presentation and the SPC gives no separate regimen for any other indication. §4.2 VERBATIM, in full: 'Adults — The usual dose is two capsules, three times daily; for some patients, up to 6g L-tryptophan may be required.' || THE COUNT IS CONVERTIBLE BECAUSE THE PRODUCT NAME PINS THE STRENGTH: the fetched product is 'Optimax 500mg Capsules', so two capsules = 1 g L-tryptophan per dose and three doses = 3 g daily. The milligram figures shown are that arithmetic on the pinned 500 mg strength — the SPC itself states the dose only as a capsule count. || ON THE 6 g FIGURE: the SPC phrases it as 'may be required' rather than as a hard ceiling, but it is the only upper figure stated anywhere in the fetched text, it is the same product, route and indication, and no other maximum appears. It is reproduced verbatim in maxDose so the wording travels with the number. Note that 6 g/day is twice the usual 3 g/day regimen. || ELDERLY, §4.2 verbatim: 'A lower dose may be appropriate, especially where there is evidence of renal or hepatic impairment.' No figure is attached to 'lower'. || ⚠️ §4.5 IS TRUNCATED at the source-fetch limit, cut off mid-sentence at 'Where L-tryptophan is combined with MAO Inhibitors such as phenelzine, moclobemide and […]'. The MAOI advice this page's interaction list depends on was therefore NOT retrieved, and neither was any dose reduction that sentence may specify. §4.4 does retrieve the serotonin-syndrome warning: 'The possible interaction between L-tryptophan and 5HT reuptake inhibitors could lead to the serotonin syndrome characterised by a combination of agitation, restlessness and gastro-intestinal symptoms including diarrhoea. Combinations with 5HT reuptake inhibitors should only be used with care.' || ADMINISTRATION TIP from §4.8: 'In some patients, L-tryptophan may cause a slight feeling of nausea which usually disappears within 2 or 3 days. Such nausea can be minimised by giving L-tryptophan after food.' || THE US CROSS-CHECK LABEL IS NOT USABLE: 'DIRECTIONS: 10 drops orally, 3 times a day' is a drop count with no strength stated anywhere in the fetched text, so it cannot be converted to a dose and is not published. It is also a different dosage form from the UK capsules. || The fetched sections do not state the licensed indication; §4.4 is written entirely around depression, antidepressant therapy and suicidality, consistent with this page's 'treatment-resistant depression — specialist psychiatry' framing, but the indication itself is unsourced in this bundle. || PAEDIATRIC: paedDose is null because the SPC establishes none. §4.2 verbatim: 'Paediatric population — The safety and efficacy of Optimax in children have not been established.' The US drops label's line 'Consult a physician for use in children under 12 years of age' carries no strength and no dose, so it adds nothing. Any paediatric use must be checked against a children's formulary and specialist advice.

Dose adjustments

Renal

No dedicated renal-impairment section was retrieved. The only statement in the fetched §4.2 appears under 'Elderly', verbatim: 'A lower dose may be appropriate, especially where there is evidence of renal or hepatic impairment.' No figure, threshold or eGFR band is given, and no statement at all is made about renal impairment in younger adults. Do not infer a specific reduction.

Hepatic

No dedicated hepatic-impairment section was retrieved. The only statement in the fetched §4.2 appears under 'Elderly', verbatim: 'A lower dose may be appropriate, especially where there is evidence of renal or hepatic impairment.' No figure is given. §4.8 lists 'increase of hepatic transaminases' among the reported features of eosinophilia myalgia syndrome. Do not infer a specific reduction.

Dose independently re-sourced from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — clinician-reviewed. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

  • §4.3 verbatim: 'Hypersensitivity to the active substance or to any of the excipients listed in section 6.1.'
  • §4.3 verbatim: 'Patients with a previous history of eosinophilia myalgia syndrome (EMS) following the use of L-tryptophan. This syndrome, which is a multisystem disorder, is characterised by raised eosinophils (>1.0 x 10^9/L), and severe myalgia in the absence of either an infectious or neoplastic cause.'
  • §4.3 verbatim: 'Patients with a known hypersensitivity to the active substance or any of the excipients.'
  • Not a §4.3 contraindication but a §4.6 instruction: 'Due to the absence of any clinical data relating to the use of Optimax in nursing mothers, Optimax should not be taken during breast feeding.'
  • The MAOI sentence sits in §4.5, which is truncated at the source-fetch limit before its advice is stated, and §4.6 says only that 'Caution should be exercised when prescribing to pregnant women'. Do not present either as a contraindication on the strength of this bundle.

Side effects

  • §4.8 verbatim: 'In some patients, L-tryptophan may cause a slight feeling of nausea which usually disappears within 2 or 3 days. Such nausea can be minimised by giving L-tryptophan after food. Other adverse reactions include headache and light-headedness.'
  • Eosinophilia myalgia syndrome (EMS), frequency not known — §4.4 verbatim: 'Eosinophilia Myalgia Syndrome (EMS) has been reported in association with the use of oral L-tryptophan-containing products. It is a multisystem disorder which is usually reversible but, rarely, fatal.'
  • Reported features of EMS, §4.4 verbatim: 'eosinophilia, arthralgia, myalgia, myopathy, fever, dyspnoea, neuropathy, sedation, somnolence, drowsiness, peripheral oedema, asthenia, fatigue, increase of hepatic transaminases, rash and skin lesions which can include sclerosis or papular and urticarial lesions.'
  • Suicidal ideation and suicidal behaviours, frequency not known — §4.8: 'Cases of suicidal ideation and suicidal behaviours (frequency not known) have been reported during L-tryptophan therapy or early after treatment discontinuation.'
  • §4.8 tabulated, all frequency 'Not known': eosinophilia myalgia syndrome; suicidal ideation; suicidal behaviours; headache; light-headedness; somnolence; sedation; oedema; myalgia; nausea; asthenia; fatigue; myopathy
  • Serotonin syndrome with 5HT reuptake inhibitors, §4.4: 'characterised by a combination of agitation, restlessness and gastro-intestinal symptoms including diarrhoea'
  • §4.8 notes on EMS frequency: 'The frequency of these events is unclear from the available data but no further new reported instances have appeared for over 20 years.'

Monitoring

  • §4.4 verbatim: 'Close supervision of patients and in particular those at high risk should accompany drug therapy especially in early treatment and following dose changes.'
  • §4.4 verbatim: 'As improvement may not occur during the first few weeks or more of treatment, patients should be closely monitored until such improvement occurs. It is general clinical experience that the risk of suicide may increase in the early stages of recovery.'
  • §4.4 verbatim: 'Patients (and caregivers of patients) should be alerted about the need to monitor for any clinical worsening, suicidal behaviour or thoughts and unusual changes in behaviour and to seek medical advice immediately if these symptoms present.' Patients with a history of suicide-related events or significant suicidal ideation before starting 'should receive careful monitoring during treatment'.
  • §4.4 verbatim, EMS: 'Caution should be exercised with patients who experience some but not all of the symptoms of EMS after taking L-tryptophan. Treatment should be withheld and the symptoms investigated until the possibility of EMS can be excluded.'
  • Eosinophil count is the objective EMS marker named by the SPC: §4.3 defines the syndrome by 'raised eosinophils (>1.0 x 10^9/L), and severe myalgia in the absence of either an infectious or neoplastic cause'. No monitoring interval or routine blood-test schedule is specified anywhere in the fetched text.
  • §4.4: use combinations with 5HT reuptake inhibitors only with care, watching for serotonin syndrome.

Clinical monograph

How it works

As a precursor in serotonin biosynthesis, it is thought to enhance central serotonergic activity, supplementing the action of conventional antidepressants.

Prescribing in practice

  • It has been associated with eosinophilia-myalgia syndrome, so it is restricted to specialist use with monitoring and patient registration in line with the SPC.
  • Combined with other serotonergic agents it increases the risk of serotonin syndrome.
  • Treatment should be reviewed for benefit, and patients monitored for eosinophilia and myalgic symptoms.

Monitoring

Monitor for eosinophilia-myalgia symptoms, including muscle pain and eosinophil count, and for features of serotonin excess.

Counselling the patient

  • Report any unexplained muscle pain, weakness or swelling promptly.
  • This medicine is used alongside other antidepressants under specialist guidance.
  • Tell your doctor about all other medicines you take, especially other antidepressants.

Evidence & guidelines

The association of tryptophan with eosinophilia-myalgia syndrome underlies its restricted specialist use, as reflected in MHRA and SPC guidance.

Reference: SmPC; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.