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What Is Orlistat?

Orlistat is a medication used for weight management alongside a reduced-calorie diet. It works in the digestive tract by reducing the absorption of some dietary fat. Prescription orlistat is marketed as Xenical in 120 mg capsules, while the over-the-counter 60 mg product is marketed as Alli. These formulations have different labeled uses and eligibility requirements. Orlistat is not an appetite suppressant and does not directly affect the brain's hunger pathways. Treatment requires attention to diet, vitamin intake, and potential medication interactions.

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What Is Orlistat?

Orlistat is a medication used for weight management alongside a reduced-calorie diet. It works in the digestive tract by reducing the absorption of some dietary fat. Prescription orlistat is marketed as Xenical in 120 mg capsules, while the over-the-counter 60 mg product is marketed as Alli. These formulations have different labeled uses and eligibility requirements. Orlistat is not an appetite suppressant and does not directly affect the brain's hunger pathways. Treatment requires attention to diet, vitamin intake, and potential medication interactions.

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How Does Orlistat Work?

Orlistat inhibits gastric and pancreatic lipases, enzymes that break down dietary triglycerides into smaller molecules that can be absorbed by the intestine. When these enzymes are blocked, some dietary fat remains undigested and passes out of the body in stool. At the prescribed 120 mg three-times-daily dose, orlistat prevents absorption of approximately 30% of dietary fat under studied conditions. Its effects occur mainly within the gastrointestinal tract, with minimal systemic absorption. Higher-fat meals can increase gastrointestinal side effects.

Who Can Use Orlistat for Weight Management?

Prescription Xenical is indicated for obesity management in adults and adolescents aged 12 years and older who meet the product's weight-related criteria. In adults, treatment is generally considered at a body mass index of at least 30, or at least 27 with additional risk factors. Over-the-counter Alli is intended for overweight adults aged 18 years and older. Orlistat should not be used during pregnancy or by people with chronic malabsorption syndrome or cholestasis. A healthcare professional should evaluate other medications and relevant medical conditions before treatment.

How Should Orlistat Be Taken?

Prescription Xenical is taken as one 120 mg capsule with each main meal containing fat, during the meal or up to one hour afterward. Over-the-counter Alli follows a similar schedule using 60 mg capsules. When a meal is skipped or contains no fat, the corresponding dose can be omitted. Patients should follow a reduced-calorie, low-fat diet and take a multivitamin containing vitamins A, D, E, and K at least two hours apart from orlistat, such as at bedtime. Certain medications require separate administration times and monitoring.

What Are the Side Effects and Warnings of Orlistat?

Common adverse effects include oily stools, gas with oily discharge, urgent bowel movements, and increased stool frequency. These symptoms are more pronounced after high-fat meals. Orlistat can reduce absorption of fat-soluble vitamins and interact with medications such as cyclosporine, warfarin, and levothyroxine. Serious concerns include rare liver injury, oxalate-related kidney stones or kidney injury, and gallbladder complications. Patients with persistent abdominal pain, jaundice, or significant bowel symptoms should seek medical evaluation. Orlistat should not be used during pregnancy.

Common Questions About Orlistat

Is orlistat the same as Xenical or Alli?

Yes. Xenical contains prescription-strength orlistat 120 mg, while Alli contains over-the-counter orlistat 60 mg. Their labeling and eligibility requirements differ.

Does orlistat suppress appetite?

No. Orlistat works in the digestive tract by reducing dietary fat absorption. It does not directly suppress appetite.

Should orlistat be taken with every meal?

Orlistat is taken with main meals containing fat, during or up to one hour after eating. The dose can be skipped when a meal is omitted or contains no fat.

Can orlistat reduce vitamin absorption?

Yes. Orlistat can reduce absorption of fat-soluble vitamins A, D, E, and K. A multivitamin should be taken at least two hours apart from the medication.

References

DailyMed - XENICAL (orlistat) capsule. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=6240792b-9224-2d10-e053-2a91aa0a2c3e. Date Accessed October 22, 2026.

Orlistat. LiverTox. https://www.ncbi.nlm.nih.gov/books/NBK548898/. Date Accessed October 22, 2026.

Orlistat. MedlinePlus. https://medlineplus.gov/druginfo/meds/a601244.html. Date Accessed October 22, 2026.

Orlistat. PubChem. https://pubchem.ncbi.nlm.nih.gov/compound/Orlistat. Date Accessed October 22, 2026.

Orlistat. StatPearls. https://www.ncbi.nlm.nih.gov/books/NBK542202/. Date Accessed October 22, 2026.