Hi & Welcome. Incomplete data like age, gender, duration of having the present problem?? Although less commonly seen, yes it may harm your kidneys. Sulfazine (Sulfasalazine) is basically a disease modifying anti-rheumatic drug (DMARD) and commonly prescribed for the treatment of rheumatoid arthritis, psoriatic arthritis, and many other types of arthritis. It is also prescribed in the treatment of inflammatory bowel disease like ulcerative colitis which you seem to be suffering from. Its most common side effects include nausea, headache, and decreased appetite. It can also cause reversible low sperm count, the numbers of white blood cells (which are needed to fight infection), red blood cells (which carry oxygen), and platelets (which help to stop bleeding). Although less common it may cause liver dysfunction and kidney damage. You need to have periodic follow up lab tests to detect the harmful effects on your liver, blood counts, or kidneys while taking Sulfazine. Hope these answer your queries.