Get emergency medical help if you have signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.
Stop using mesalamine and call your doctor at once if you have:
severe stomach pain, stomach cramping, bloody diarrhea;
fever, headache, general ill feeling;
rash, itching, eye redness;
bloody or tarry stools, coughing up blood or vomit that looks like coffee grounds;
low white blood cell counts--fever, chills, mouth sores, skin sores, sore throat, cough, feeling light-headed, trouble breathing;
signs of a kidney stone--severe pain in your side and back, frequent need to urinate, foul-smelling urine, dark or cloudy urine;
kidney problems--increased or decreased urination, swelling, weight gain; or
liver problems--loss of appetite, upper stomach pain, tiredness, easy bruising or bleeding, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes).
Low white blood cell counts may be more likely in older adults.
Common side effects may include:
burping, constipation, nausea, vomiting, stomach pain, diarrhea, gas;
dizziness;
cold symptoms such as stuffy nose, sneezing, sore throat;
back pain;
headache;
rash; or
abnormal liver function tests.
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
 Mesalamine side effects (more detail)
