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DMARD / Anti-inflammatory

Sulfasalazine

Brand names: Salazopyrin EN

Sulfasalazine is used as a disease-modifying drug in rheumatoid and other inflammatory arthritis, and in inflammatory bowel disease.

Dosing — being independently re-sourced

ClinCalc Pro is rebuilding its dose data from primary open sources — the manufacturer SmPC (eMC), the WHO Model Formulary and other official references — under clinician review. This drug's structured dose is not yet published here. Confirm all doses against the product SmPC and your local formulary before prescribing.

US labelling (FDA)

Reference — US labelling, may differ from UK

DOSAGE AND ADMINISTRATION The dosage of Sulfasalazine Tablets should be adjusted to each individual’s response and tolerance. Initial Therapy: Adults: 3 to 4 g daily in evenly divided doses with dosage intervals not exceeding eight hours. In some cases, it is advisable to initiate therapy with a smaller dosage, e.g., 1 to 2 g daily, to reduce possible gastrointestinal intolerance. If daily doses exceeding 4 g are required to achieve desired effects, the increased risk of toxicity should be kept in mind. Children, six years of age and older: 40 to 60 mg/kg body weight in each 24-hour period, divided into 3 to 6 doses. Maintenance Therapy: Adults: 2 g daily. Children, six years of age and …

Source: US FDA prescribing information (openFDA / DailyMed), label dated 2022-12-12. Accessed 2026-06-12. US dosing and indications can differ from UK practice — use UK sources for prescribing decisions.

Clinical monograph

How it works

It is split in the colon into 5-aminosalicylic acid (acting locally in the gut) and sulfapyridine, the latter relevant to its systemic effects and toxicity.

Prescribing in practice

  • Blood dyscrasias and hepatotoxicity can occur, especially early — monitor FBC and liver function; rash and gastrointestinal upset are common.
  • It can harmlessly turn urine and soft contact lenses orange and cause a reversible reduction in sperm count.
  • Use caution in G6PD deficiency and sulphonamide allergy.

Monitoring

Monitor FBC and liver function regularly (more often at initiation); review response.

Counselling the patient

  • Report sore throat, fever, unexplained bruising, or yellowing of the skin/eyes.
  • It can turn urine and soft contact lenses orange (harmless).
  • It can take weeks to work.

Evidence & guidelines

A conventional DMARD in inflammatory arthritis and a treatment in inflammatory bowel disease, with FBC/LFT monitoring.

Reference: BSR/BHPR RA Guidelines; NICE NG100; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

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