Sulfasalazine is used to treat rheumatoid arthritis; or stomach pain, rectal bleeding, and diarrhea caused by ulcerative colitis or Crohn’s disease. It is sold under the brand name Azulfidine.

Side effects include stomach upset, diarrhea, nausea, vomiting, headache, drowsiness, or dizziness. Some people have problems sleeping the first few days of taking the medication. Notify your doctor if these symptoms persist or are severe. The drug can change the urine to a brownish orange color; the color change is not serious. Another common symptom is sensitivity to sunlight, and the patient may be more prone to sunburn.

If you are taking this drug and develop a skin rash, blisters, dark urine, unusual fatigue, persistent sore throat, persistent fever, jaundice (yellowing of the eyes or skin), or abdominal pain, contact your doctor immediately. There are rare side-effects of this medication that are serious and possibly fatal. One such serious side-effect is a peeling skin rash, known as Stevens-Johnson syndrome. Liver damage is also possible, so call your doctor if you develop jaundice. Blood disorders like agranulocytosis or aplastic anemia are also possible serious side-effects.