Sulfasalazine

Key facts

• Sulfasalazine combines a sulfa-type component with an anti-inflammatory released in the gut, and treats inflammatory bowel disease and inflammatory arthritis.
• You usually take it several times a day with food, and your doctor may start at a low dose and increase it gradually to reduce stomach upset.
• Do not take sulfasalazine if you have an allergy to sulfonamides (sulfa drugs) or salicylates such as aspirin; regular blood counts are needed because it can rarely cause serious drops in blood cell counts.
• Seek urgent care for fever, sore throat, unusual bruising, or a spreading rash, which can signal a blood or skin reaction.

What sulfasalazine treats

Sulfasalazine treats ulcerative colitis, reducing inflammation, cramping, and rectal bleeding in the colon, and Crohn's disease affecting the large intestine. It also treats rheumatoid arthritis and ankylosing spondylitis, easing joint pain, stiffness, and swelling when other treatments are not enough.

How sulfasalazine works

The tablet passes largely unchanged through the stomach and small intestine. In the colon, gut bacteria split it into two parts: a sulfa-type component and 5-aminosalicylic acid, the part that reduces inflammation directly in the lining of the gut. The same anti-inflammatory action is thought to help calm joint inflammation in arthritis.

Before you take it

• Do not use sulfasalazine if you have a sulfonamide or salicylate allergy, or a history of the blood disorder porphyria.
• Tell your doctor about kidney or liver disease, glucose-6-phosphate dehydrogenase (G6PD) deficiency, and any current infection, fever, or unexplained bruising.
• Blood counts, and often liver function, are checked regularly, especially in the first few months, because sulfasalazine can rarely cause agranulocytosis or other blood dyscrasias.
• It can reduce folic acid absorption; your doctor may recommend a folic acid supplement.

Side effects

Common effects include nausea, headache, loss of appetite, and a harmless orange-yellow discoloration of urine and skin.

Stop and seek urgent medical care for:

• Fever, sore throat, mouth ulcers, or unusual bruising or bleeding, which can signal a blood cell problem.
• A severe or spreading rash, blistering, or peeling skin.
• Yellowing of the skin or eyes.
• Shortness of breath or a new cough.

Safety essentials

• Sulfasalazine can cause serious blood dyscrasias; regular full blood counts are mandatory, particularly during the first few months of treatment, and any fever, sore throat, or unusual bruising needs urgent review.
• Never start sulfasalazine if you have a known sulfa or salicylate allergy.
• Keep all monitoring appointments, since blood, liver, and kidney checks continue throughout long-term treatment.

This page is educational and does not replace advice from a doctor or pharmacist who knows your health history.