Reviewed by: HU Medical Review Board | Last reviewed: February 2019 | Last updated: November 2020

Sulfasalazine is a slow-acting anti-rheumatic drug (SAARD) that may be used to treat certain people with ankylosing spondylitis (AS). Sulfasalazine is an anti-inflammatory drug and is also used to treat rheumatoid arthritis and ulcerative colitis, a type of inflammatory bowel disease.1,2

Treatment recommendations for AS recommend against using sulfasalazine to manage AS, as there is little to no evidence for its effectiveness in treating AS. In research studies, sulfasalazine had a small beneficial effect on spinal pain but not on other outcomes that were measured, and it has a higher risk of side effects than placebo. Treatment with sulfasalazine may be considered for certain patients who cannot tolerate TNF (tumor necrosis factor) inhibitors and those who have prominent peripheral AS (in the arms and legs).3

Sulfasalazine is available in generic form and also sold under the brand name Azulfidine.

What is the active ingredient in sulfasalazine?

The active ingredient in Azulfidine is sulfasalazine. In the brand form of Azulfidine EN-tabs®, the active ingredient is sulfasalazine formulated in an enteric-coated, delayed-release tablet.4

How does sulfasalazine work?

Sulfasalazine is a type of sulfa drug. While the exact way it works isn’t fully understood, researchers believe that sulfasalazine or its metabolites (the substances it turns into when the body breaks it down) interfere with the inflammatory or immune system processes.4

What are the possible side effects of sulfasalazine?

Sulfasalazine may cause side effects, including diarrhea, headache, loss of appetite, upset stomach, vomiting or stomach pain. Any side effects that are experienced by the patient should be reported to a healthcare professional.1

Some side effects may be serious. If patients taking sulfasalazine notice sore throat, fever, a pale appearance (pallor), purple spots on the skin (purpura), or jaundice (a yellowing of the whites of the eyes or skin), they should immediately contact their doctor, as these may be signs of a serious blood disorder.4

Some people experience an allergic reaction to sulfasalazine, which may cause skin rash, itching, hives, swelling, or difficulty swallowing. If this occurs, the patient should stop taking sulfasalazine and contact their doctor immediately.1

Things to know about sulfasalazine

Before starting treatment with sulfasalazine, patients should talk to their doctor about all their medical conditions, especially:4

  • An allergy to sulfasalazine, aspirin, or any other drugs
  • A history of urinary or intestinal blockage
  • Porphyria (a group of disorders that affect the nervous system or skin)
  • Asthma
  • Kidney disease
  • Liver disease
  • Pregnant or plan to become pregnant or are breastfeeding

Patients should discuss with their doctors all the medications, supplements, and vitamins they take as some may interfere with sulfasalazine or cause an increase in side effects.4

People taking methotrexate should avoid unnecessary or prolonged sun exposure and should avoid using tanning beds or sunlamps, as methotrexate can make the skin more sensitive.4

Dosing information

Sulfasalazine comes in a tablet that should be taken with food and plenty of water to reduce the chance of an upset stomach. Patients should talk to their doctor about any questions on their dosing regimen.

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