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Disease-Modifying Therapy — Relapsing-Remitting Multiple Sclerosis Pregnancy: Contraindicated — teratogenic in animals; effective contraception mandatory

Dimethyl Fumarate

Brand names: Tecfidera

Adult dose

Dose: 120 mg twice daily for 7 days, then 240 mg twice daily
Route: Oral
Frequency: Twice daily with food
Max: 480 mg/day
Oral disease-modifying therapy for relapsing-remitting MS (RRMS). Activates Nrf2 pathway — anti-inflammatory and neuroprotective. Reduces annualised relapse rate by ~50%. Take with food to reduce flushing. CONFIRM and DEFINE trials demonstrated efficacy.

Paediatric dose

Route:
Seek specialist opinion — not licensed in children under 18 years.

Dose adjustments

Renal

No dose adjustment required.

Hepatic

No dose adjustment required.

Clinical pearls

  • MHRA: lymphocyte monitoring mandatory — if lymphocytes <0.5 × 10⁹/L for >6 months, consider stopping (PML risk). JC virus antibody testing before and during treatment if lymphopenic.
  • PML (progressive multifocal leukoencephalopathy) — JC virus opportunistic infection causing severe brain damage. Risk increases dramatically with prolonged lymphopenia. MRI surveillance if lymphopenic.
  • Flushing management: take with food, start on 120 mg BD, use aspirin 30 min before dose, or switch to diroximel fumarate (Vumerity — fewer GI/flushing side effects, same mechanism)

Contraindications

  • Severe active infection
  • Severe renal impairment (limited data)
  • Pregnancy

Side effects

  • Flushing (very common — 40%; usually first month; aspirin 75–325 mg before dose reduces flushing)
  • GI side effects (nausea, diarrhoea, abdominal pain — take with food)
  • Lymphopenia (MHRA warning — monitor lymphocytes)
  • Progressive multifocal leukoencephalopathy (PML — JC virus, risk if lymphocyte count persistently <0.5 × 10⁹/L)
  • Elevated LFTs

Interactions

  • Fumaric acid preparations (additive)
  • Dimethyl fumarate may reduce efficacy of live vaccines

Monitoring

  • FBC with lymphocyte count: baseline, 6 months, then every 6–12 months
  • LFTs
  • Renal function (urinalysis — proteinuria)
  • JC virus antibody titre annually

Reference: BNFc; BNF 90; NICE TA320 (Dimethyl Fumarate for MS); MHRA Lymphopenia Safety Update; DEFINE/CONFIRM Trials. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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