The most common side effects, which are more likely to take place during the first week of treatment but might continue through the use of this med, may include oily spotting on underwear or on clothing, gas with oily spotting, urgent need to have a bowel movement, loose stools, oily or fatty stools, increased number of bowel movements, difficulty controlling bowel movements, pain or discomfort in the rectum (bottom), stomach pain, irregular menstrual periods, headache and anxiety. If you experience serious effects such as hives, rash, itching, difficulty breathing or swallowing or severe or continuous abdominal pain, contact your local doctor immediately.