sulfasalazine at a glance
Medicine class
Aminosalicylate anti-inflammatory and disease-modifying antirheumatic treatment.
Main uses
Ulcerative colitis, active Crohn’s disease and, with gastro-resistant tablets, rheumatoid arthritis.
What is sulfasalazine used for?
Licensed uses vary by formulation.
Standard tablets and oral suspension: ulcerative colitis and active Crohn’s disease.
Gastro-resistant tablets: inflammatory bowel disease and rheumatoid arthritis that has not responded adequately to non-steroidal anti-inflammatory medicines.
Suppositories: ulcerative colitis or Crohn’s disease affecting the rectum.
How does sulfasalazine work?
Gut bacteria split oral sulfasalazine into sulfapyridine and mesalazine. These components and unchanged sulfasalazine modify inflammatory pathways; mesalazine acts mainly in the colon, while systemic immune-modifying effects contribute to its action in rheumatoid arthritis.
sulfasalazine preparations and strengths
Gastro-resistant tablet
Route: Oral
Strengths: 500 mg
Oral suspension
Route: Oral
Strengths: 250 mg/5 mL
Tablet
Route: Oral
Strengths: 500 mg
Suppository
Route: Rectal
Strengths: 500 mg
How to take sulfasalazine
Follow the directions for your prescribed formulation and do not stop treatment without discussing it with the prescriber.
Swallow tablets with water. Do not crush or break gastro-resistant tablets.
Tablets can generally be taken with or without food; the oral suspension should be taken with food.
Drink adequate fluids during oral treatment.
For suppositories, insert after opening the bowels when possible, wash hands before and afterwards, and try to retain the suppository.
sulfasalazine side effects
Common or expected effects
- Nausea, indigestion or abdominal discomfort
- Diarrhoea or vomiting
- Headache or dizziness
- Reduced appetite
- Rash
- Taste changes, cough or sore mouth
- Harmless orange-yellow urine; some soft contact lenses may stain
Get urgent medical advice
- Severe blistering, peeling or ulcerating skin reaction
- Anaphylaxis or other severe hypersensitivity
- Fever, sore throat, mouth ulcers, pallor, bruising or bleeding suggesting a blood disorder
- Jaundice or other symptoms of liver injury
- Reduced urine or painful urination suggesting kidney injury
- Persistent breathlessness, dry cough or chest pain
- Severe abdominal or back pain with vomiting or fever, which may indicate pancreatitis
sulfasalazine in pregnancy
Sulfasalazine can be used during pregnancy when recommended by a specialist. It can lower folate levels, so people planning pregnancy or who are pregnant should discuss prescribed higher-strength folic acid with their clinician. Do not stop effective treatment without specialist advice, because uncontrolled inflammatory disease can also affect pregnancy.
sulfasalazine while breastfeeding
Sulfasalazine may be used while breastfeeding a healthy baby after discussion with a clinician, although selected product information advises avoiding breastfeeding. Individual review is important, especially for a premature or unwell infant. Seek advice if the baby develops diarrhoea, vomiting, rash, jaundice or unusual irritability.
sulfasalazine interactions
Tell the prescriber or pharmacist about all medicines, supplements and herbal products. Important examples include:
Digoxin
Oral sulfasalazine can reduce digoxin absorption and may produce inadequate blood concentrations.
Azathioprine or mercaptopurine
The combination can increase bone-marrow suppression and low white-cell counts, requiring careful monitoring.
Methotrexate
Combined treatment may increase gastrointestinal adverse effects, particularly nausea.
Glucose-lowering medicines
Sulfonamide-related effects may increase the risk of low blood glucose, so closer monitoring may be needed.
Common questions about sulfasalazine
Answers are fully visible for fast scanning and source review.
Why are blood tests needed?
Tests check for uncommon but potentially serious effects on blood cells, the liver and kidneys before symptoms become severe.
Can gastro-resistant tablets be crushed?
No. Crushing or breaking them damages the coating designed to prevent disintegration in the stomach.
Can it turn urine orange?
Yes. Orange-yellow urine is a recognised and usually harmless effect, although unexpected urinary symptoms should still be assessed.
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.