Common side effects associated with aminosalicylates include nausea, abdominal pain, headache, dizziness and fatigue. In rare cases, these drugs can cause inflammation of the liver (hepatitis) or inflammation of the pancreas (pancreatitis).  

Symptoms such as fatigue, abdominal pain and dizziness are related to the dosage level of the patient. Reducing the dosage level may cause a corresponding decrease in the incidence of side effects. However, the incidence of conditions such as hepatitis and pancreatitis is unrelated to dosage levels.

Sulfasalazine is more likely than other aminosalicylates to trigger side effects. Most side effects are associated with the ingredient sulfapyridine, which carries the anti-inflammatory ingredient 5-aminosalicylic acid (5-ASA) to the intestines. Sulfasalazine use is closely associated with many side effects such as fever, nausea, diarrhea, headache, rash, change in color of urine and skin to yellow-orange hue, reduced sperm count (in men) and, less commonly, pancreatitis, hepatitis, lung inflammation (pneumonitis), Stevens-Johnson syndrome ( a skin reaction) and destruction of the red blood cells (hemolysis).   The other aminosalicylates have different carriers that are less likely to cause side effects.