The following side effects occur commonly with the use of orlistat. They are the natural effects of orlistat's fat-blocking action and are actually signs that the medication is working properly. These side effects are usually temporary and may lessen as you continue treatment with orlistat:
- oily spotting in your undergarments;
- oily or fatty stools;
- orange or brown colored oil in your stool;
- gas with discharge, an oily discharge;
- loose stools, or an urgent need to go to the bathroom, inability to control bowel movements;
- an increased number of bowel movements;
- stomach pain, nausea, vomiting, diarrhea, rectal pain; or
- weakness, dark urine, clay-colored stools, itching, loss of appetite, or jaundice (yellowing of the skin or eyes).
Other side effects that may occur while taking orlistat include:
- problems with your teeth or gums;
- cold symptoms such as stuffy nose, sneezing, cough;
- fever, chills, sore throat, flu symptoms;
- headache, back pain; or
- mild skin rash.