Mesalamine, also known as mesalazine or 5-aminosalicylic acid (5-ASA), is a medication used to treat inflammatory bowel disease, including ulcerative colitis and Crohn’s disease. It is generally used for mildly to moderately severe disease. Mesalamine can be taken by mouth or rectally. It is part of a group of anti-inflammatory medicines called aminosalicylates (5-ASA), which bring down swelling in the intestine lining and help it heal