Pentasa (Mesalamine) is an anti-inflammatory used to treat ulcerative colitis. SWALLOW WHOLE. Do not break, crush, or chew before swallowing. You may take this medicine with food or milk to decrease the chance for stomach upset. DO NOT TAKE THIS MEDICINE IF YOU HAVE HAD A SEVERE ALLERGIC REACTION to aspirin or any medicine containing aspirin. A severe reaction includes a severe rash, hives, breathing difficulties, or dizziness.