Adverse reactions to orlistat are largely gastrointestinal in nature. The incidence of adverse events decreased with prolonged use of orlistat. Other adverse effects reported are headache, upper respiratory infection, lower respiratory infection, abdominal pain/discomfort, oily spotting from the rectum, flatus with discharge, faecal urgency, fatty/oily stool, flatulence, liquid stools, oily evacuation, increased defecation, rectal pain, soft stools, faecal incontinence, abdominal distension, tooth disorder, gingival disorder, urinary tract infection, hypoglycaemia, influenza, fatigue, menstrual irregularity, anxiety, etc.