Most Common Effects

• The most common side effects associated with mesalamine are headache and gas. Some people experience slight hair loss and itchy skin.
  
  

Gastrointestinal Side Effects

• Other gastrointestinal side effects of mesalamine include burping, constipation, heartburn, nausea, vomiting, rectal pain and hemorrhoids.
  
  

Severe Gastrointestinal Reaction

• Mesalamine can cause a severe reaction that is easily confused with a flare-up of ulcerative colitis. Symptoms include abdominal pain, cramping and bloody diarrhea. Fever, headache and rash also might occur.
  
  

Uncommon Side Effects

• Many other side effects are possible but uncommon. These include acne, back pain, joint pain, muscle pain, fatigue, dry mouth, sore throat, coughing, nasal congestion, runny nose, earache and unusual perspiration.
  
  

Serious Side Effects

• More serious but infrequent side effects include chest pain, shortness of breath, blood disorders, increased heart rate, kidney dysfunction and pancreatitis. Increased bleeding also can occur, with symptoms of coughing or vomiting blood, and blood in urine or stools.