Mesalamine, also known as 5-aminosalicylic acid (5-ASA), is used primarily in the treatment of inflammatory bowel diseases (IBD) such as ulcerative colitis and Crohn’s disease. It works by reducing inflammation in the colon and rectum, helping to manage symptoms like diarrhea, abdominal pain, and rectal bleeding. Mesalamine is generally considered safer than corticosteroids for long-term use in IBD management.