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DMARD / Anti-inflammatory Pregnancy: Generally considered safe in pregnancy (used in IBD). Ensure adequate folic acid supplementation.

Sulfasalazine

Brand names: Salazopyrin EN

Adult dose

Dose: 500 mg daily initially; increase by 500 mg/week to 1–3 g/day in divided doses
Route: Oral (enteric-coated tablets — EN formulation preferred for RA)
Frequency: Twice daily
Max: 3 g/day (RA); up to 4 g/day (IBD)
RA: Start 500 mg/day, increase weekly by 500 mg to 2–3 g/day (usually 1 g BD). IBD: up to 4 g/day in divided doses. EN-coated preferred to reduce GI side effects. Take after food.

Paediatric dose

Dose: 30 mg/kg
Route: Oral
Frequency: Twice to four times daily
Max: 2 g/day (children — JIA)
JIA (≥6 years): start 10 mg/kg/day, increase to 30–50 mg/kg/day (max 2 g/day). IBD (specialist): higher doses. Dissolve in water or crush if tablets too large.

Dose adjustments

Renal

Use with caution; reduce dose if renal impairment. Avoid if severe renal failure.

Hepatic

Avoid in significant hepatic impairment; monitor LFTs.

Paediatric weight-based calculator

JIA (≥6 years): start 10 mg/kg/day, increase to 30–50 mg/kg/day (max 2 g/day). IBD (specialist): higher doses. Dissolve in water or crush if tablets too large.

Clinical pearls

  • Commonly used in RA triple therapy (MTX + HCQ + SSZ)
  • Oligospermia reversible on stopping — advise men wanting to conceive
  • Urinary discolouration (orange/yellow) is harmless — warn patient
  • Slow onset: 4–12 weeks for clinical benefit
  • BSR monitoring: FBC, LFTs monthly for first 3 months then 3-monthly

Contraindications

  • Hypersensitivity to sulfonamides or aspirin
  • G6PD deficiency (haemolysis risk)
  • Porphyria
  • Severe renal or hepatic impairment

Side effects

  • GI upset (nausea, abdominal pain — EN formulation reduces this)
  • Rash and urticaria
  • Reversible oligospermia (male infertility — resolves on stopping)
  • Haematological toxicity (agranulocytosis, aplastic anaemia — rare)
  • Hepatotoxicity
  • Headache
  • Orange-yellow discolouration of urine and body fluids

Interactions

  • Methotrexate — increased folate deficiency risk
  • Folic acid — reduced absorption by sulfasalazine
  • Digoxin — reduced digoxin absorption
  • Anticoagulants — enhanced effect

Monitoring

  • FBC (monthly initially then 3-monthly)
  • LFTs
  • U&E
  • Urinalysis

Reference: BNFc; BNF; BSR/BHPR RA Guidelines; NICE NG100. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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