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5-HT2 antagonist (antihistamine) Pregnancy: Clinical data in pregnancy are very limited — pizotifen should only be prescribed or administered under compelling circumstances. Breast-feeding: although milk concentrations in treated mothers are not likely to affect breast-fed infants, use in nursing mothers is not recommended (section 4.6).

Pizotifen

Brand names: Sanomigran

Pizotifen is an antihistamine and serotonin (5-HT2) antagonist used for the prophylaxis of migraine, including in children, and of recurrent vascular headache.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: Usually 1.5 mg daily, adjusted to individual patient requirements
Route: Oral
Frequency: As a single dose at night or in three divided doses (up to 3 mg may be given as a single dose)
Max: 4.5 mg daily
Children and adolescents from 2 years of age: up to 1.5 mg daily, usually as a divided dose, although up to 1 mg has been given as a single dose at night — this is an age-based, not a per-kg, regimen; verify against a children's formulary. Elderly: clinical work has not shown that elderly patients require different dosages from younger patients. Renal or hepatic impairment: caution is required and dosage adjustment may be necessary. Gradual withdrawal is recommended — withdrawal symptoms (depression, tremor, nausea, anxiety, malaise, dizziness, sleep disorder, weight decrease) have been reported after abrupt cessation. Discontinue if there is any clinical evidence of hepatic dysfunction until the cause is determined.

Dose adjustments

Renal

Caution is required in patients with renal or hepatic impairment and dosage adjustment may be necessary; dosage adjustment may be necessary in patients with kidney insufficiency (sections 4.2 and 4.4).

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

  • Hypersensitivity to pizotifen or to any of the excipients

Side effects

  • Appetite stimulation and increase in body weight (very common)
  • Drowsiness including somnolence, and dizziness (common); fatigue (common)
  • Nausea and dry mouth (common); constipation (uncommon)
  • Hepatic enzyme increased, jaundice, hepatitis (frequency unknown) — ranging from transaminase elevations to severe hepatitis
  • Depression, CNS stimulation (aggression, agitation, restlessness, excitability), hallucination, insomnia, anxiety (rare); seizures (very rare)

Interactions

  • Monoamine oxidase inhibitors (MAOIs) — pizotifen should not be used in patients receiving MAOIs
  • Alcohol — its effect may be enhanced
  • Tranquillisers, hypnotics, antihistamines (including certain common cold preparations) and antidepressants — pizotifen may increase and prolong the drowsiness these cause
  • Adrenergic neurone blockers (antihypertensives) — their hypotensive effect is antagonised by pizotifen
  • Drugs that undergo exclusively glucuronidation — increased plasma concentrations of pizotifen cannot be excluded (pizotifen is extensively metabolised by N-glucuronidation)

Clinical monograph

How it works

It blocks serotonin 5-HT2, histamine and muscarinic receptors, and this antiserotonergic action is thought to underlie its migraine-preventive effect.

Prescribing in practice

  • Weight gain and increased appetite are common and frequently limit its long-term use.
  • It has sedative and antimuscarinic properties, so use caution in glaucoma, urinary retention, and where drowsiness would be hazardous.
  • Doses are often weighted toward bedtime to reduce daytime sedation, and it should not be stopped abruptly after prolonged use.

Monitoring

Monitor weight, appetite, and the degree of sedation, alongside the frequency and severity of migraine attacks to judge benefit.

Counselling the patient

  • This medicine is taken to prevent migraines, not to treat an attack once it has started.
  • It commonly causes drowsiness and increased appetite with weight gain; taking more of the dose at night can help with sleepiness.
  • For children, follow the dose in a children's formulary exactly as prescribed.

Evidence & guidelines

Pizotifen is a long-established migraine prophylactic recognised in NICE guidance, with efficacy supported by clinical experience and trial data.

Reference: NICE CG150; 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.

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