Orlistat -the active ingredient in Xenical® and Alli®- blocks some of the fat that you eat from being absorbed by your body. Orlistat is used in the management of obesity including weight loss and weight maintenance when used with a reduced-calorie diet.
Orlistat also marketed as:
Alli, Orlipastat, Orlipastatum, Xenical.
Side effects can vary but Drugs.com has a great list of all of the risk and information.
Tell your doctor your complete medical history especially if you have high blood pressure, an over-active thyroid, glaucoma, diabetes or mental problems. Consult with your doctor if you think you are pregnant or before breast-feeding. can be habit forming and must be used with caution. Alcohol can increase unwanted side effects of dizziness. Limit alcohol use. This drug is not recommended for use in children. Consult your doctor or pharmacist for further information.
Do not let anyone else take your medication. Ask your rx pharmacist any questions you have about refilling your prescription.
If you miss a dosage of your medication, do not double the next dose. Instead, skip the missed dose and resume your usual dosing schedule. Take the missed dose as soon as you remember it. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.