Hair loss is a rare side effect of Pentasa^® (mesalamine). In clinical studies, less than 1 percent of people reported hair loss as one of the Pentasa side effects. Given how common hair loss is in the general public, however, it is difficult to determine whether this is actually caused by Pentasa or other factors. If you experience hair loss while taking the drug, talk with your healthcare provider. Depending on how severe the hair loss is, there are things that he or she may be able to do. If the hair loss is bothersome to you, your healthcare provider may recommend adjusting the Pentasa dosage or trying another medication for ulcerative colitis.