HealthyStudy

Orlistat

Lipase inhibitor. Sold as Xenical, Alli.

FDA approved for weight lossNo approved genericAvailable over the counter

Orlistat is the only medication in this category that acts in the gut rather than on the brain or on hormone receptors. It is also the only one available without a prescription: Xenical is the 120 mg prescription capsule, Alli is the 60 mg over-the-counter version.

Brands and what each one is approved for

One active ingredient can hold several separate FDA approvals. They are different documents with different approved uses, and mixing them up is the most common mistake made about these medications.

BrandStatus for this useSupplyLabel version
XenicalH2-Pharma LLCApproved for weight lossPrescription9 January 2026
AlliHaleon US Holdings LLCApproved for weight lossOver the counter18 March 2026

How it works

Written by us

Orlistat blocks the enzymes that break down dietary fat, so a portion of the fat eaten passes through undigested. The label describes this as an inhibition of gastric and pancreatic lipases. Because it acts inside the digestive tract, its systemic absorption is minimal.

From the mechanism of action section of the Xenical label

Orlistat is a reversible inhibitor of gastrointestinal lipases. It exerts its therapeutic activity in the lumen of the stomach and small intestine by forming a covalent bond with the active serine residue site of gastric and pancreatic lipases.

What the FDA approved it for

The approved uses, as worded in the label.

From the FDA label

Xenical

  • XENICAL is indicated for obesity management including weight loss and weight maintenance when used in conjunction with a reduced-calorie diet.
  • XENICAL is also indicated to reduce the risk for weight regain after prior weight loss.
  • XENICAL is indicated for obese patients with an initial body mass index (BMI) ≥30 kg/m 2 or ≥27 kg/m 2 in the presence of other risk factors (e.g., hypertension, diabetes, dyslipidemia).
  • Table 1 illustrates body mass index (BMI) according to a variety of weights and heights.

Alli

  • Weight loss aid
  • for weight loss in overweight adults, 18 years and older, when used along with a reduced-calorie and low-fat diet

Forms and strengths

The presentations and strengths listed in the label.

From the FDA label

Xenical

  • XENICAL 120 mg turquoise capsules imprinted with XENICAL 120 in black ink.
  • Capsules: 120 mg.

Alli

Orlistat 60 mg

How the label says it is taken

What the label states about administration. It is not a dosing instruction for any individual.

From the FDA label

Xenical

  • One 120-mg capsule three times a day with each main meal containing fat (during or up to 1 hour after the meal).
  • Advise patients to take a nutritionally balanced, reduced-calorie diet that contains approximately 30% of calories from fat.
  • Distribute the daily intake of fat, carbohydrate, and protein over three main meals.
  • Advise patients to take a multivitamin containing fat-soluble vitamins to ensure adequate nutrition.
  • Take the vitamin supplement at least 2 hours before or after the administration of XENICAL, such as at bedtime.
  • For patients receiving both XENICAL and cyclosporine therapy, administer cyclosporine 3 hours after XENICAL.

Alli

  • read the enclosed brochure for other important information
  • diet and exercise are the starting points for any weight loss program. Try these first before adding orlistat. Check with your doctor before starting any exercise program.
  • to see if orlistat capsules are right for you, find your height on the chart to the right. You may consider starting a weight loss program with orlistat if your weight is the same or more than the weight shown for your height.
  • for overweight adults 18 years and older: take 1 capsule with each meal containing fat
  • do not take more than 3 capsules daily
  • use with a reduced-calorie, low-fat diet and exercise program until you reach your weight loss goal. Most weight loss occurs in the first 6 months.
  • if you stop taking orlistat, continue with your diet and exercise program
  • if you start to regain weight after you stop taking orlistat, you may need to start taking orlistat again along with your diet and exercise program
  • take a multivitamin once a day, at bedtime, when using orlistat

Most common adverse reactions

The adverse reactions the label reports as most common.

From the FDA label

Xenical

most common adverse events resulting in discontinuation of treatment were gastrointestinal.

Alli

  • you develop itching, yellow eyes or skin, dark urine or loss of appetite. There have been rare reports of liver injury in people taking orlistat.
  • you develop severe pain in the back or groin, painful urination, blood in your urine, swelling of the legs or feet, or are urinating less often than normal. There have been rare reports of kidney injury in people taking orlistat.
  • severe or continuous abdominal pain occurs. This may be a sign of a serious medical condition.
  • you are taking medicine for seizures and your seizures happen more often or get worse

Warnings and precautions

The warnings and precautions section of the label.

From the FDA label

Xenical

  • XENICAL has drug interactions and can decrease vitamin absorption.
  • Take a multivitamin supplement that contains fat-soluble vitamins to ensure adequate nutrition.
  • Rare cases of severe liver injury with hepatocellular necrosis or acute hepatic failure have been reported.
  • Patients may develop oxalate nephrolithiasis and oxalate nephropathy following treatment with XENICAL. Monitor renal function in patients at risk for renal insufficiency. Discontinue XENICAL if oxalate nephropathy develops.
  • Substantial weight loss can increase the risk of cholelithiasis.
  • Exclude organic causes of obesity (eg, hypothyroidism) before prescribing XENICAL.
  • Gastrointestinal events may increase when XENICAL is taken with a diet high in fat (>30% total daily calories from fat).

Alli

  • gallbladder problems
  • kidney disease or kidney stones
  • pancreatitis
  • take a multivitamin once a day, at bedtime . Orlistat can reduce the absorption of some vitamins.
  • follow a well-balanced, reduced-calorie, low-fat diet. Try starting this diet before taking orlistat.
  • orlistat works by preventing the absorption of some of the fat you eat. The fat passes out of your body, so you may have bowel changes. You may get: gas with oily spotting
  • loose stools
  • more frequent stools that may be hard to control
  • eating a low-fat diet lowers the chance of having these bowel changes
  • for every 5 pounds you lose from diet alone, orlistat can help you lose 2-3 pounds more. In studies, most people lost 5-10 pounds over 6 months.

Contraindications

Situations in which the label states the medication must not be used.

From the FDA label

Xenical

XENICAL is contraindicated in: Pregnancy Patients with chronic malabsorption syndrome Patients with cholestasis Patients with known hypersensitivity to XENICAL or to any component of this product Pregnancy Chronic malabsorption syndrome Cholestasis Known hypersensitivity to XENICAL or to any component of this product

Alli

  • if you are taking cyclosporine
  • if you have been diagnosed with problems absorbing food
  • if you are not overweight

Drug interactions

Interactions the label singles out.

From the FDA label

Xenical

  • Cyclosporine: Reduction in cyclosporine plasma levels was observed when XENICAL was coadministered with cyclosporine.
  • Fat-soluble Vitamin Supplements and Analogues: All patients should take a daily multivitamin that contains vitamins A, D, E, K, and beta-carotene.
  • Levothyroxine: Patients treated concomitantly with XENICAL and levothyroxine should be monitored for changes in thyroid function.
  • Warfarin: Patients on chronic stable doses of warfarin who are prescribed XENICAL should be monitored closely for changes in coagulation parameters.
  • Amiodarone: A reduction in exposure to amiodarone was observed when XENICAL was co-administered.
  • Antiepileptic Drugs: Convulsions have been reported in patients taking XENICAL with antiepileptic drugs. Patients should be monitored for possible changes in frequency or severity of convulsions.

Pregnancy and breastfeeding

The opening of the pregnancy section of the label. The full section is longer and is in the source document.

From the FDA label

Xenical

Pregnancy Category X XENICAL is contraindicated during pregnancy, because weight loss offers no potential benefit to a pregnant woman and may result in fetal harm. A minimum weight gain, and no weight loss, is currently recommended for all pregnant women, including those who are already overweight or obese, due to the obligatory weight gain that occurs in maternal tissues during pregnancy.

Generic or brand

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Both strengths are sold under their original approvals. The FDA label database lists no approved generic application for orlistat, so this is a brand product in both the prescription and the over-the-counter form.

The FDA label database lists no approved generic application for this ingredient.

What affects the cost

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The over-the-counter strength is bought directly, without a prescription, which puts it in a different cost category from everything else on this page. This site does not track prices and does not link to sellers.

Common questions

What is the difference between Xenical and Alli?
The dose. Xenical is 120 mg per capsule and requires a prescription. Alli is 60 mg and is sold over the counter under a Drug Facts label. Both are linked on this page.
Why is orlistat associated with digestive side effects?
Because undigested fat passes through the gut. The labels list gastrointestinal effects and connect them directly to the amount of fat in the diet.

Other medications under weight loss

Whether each one carries an FDA approval for this use is marked on its page and in this list.

Sources

Every fact above comes from one of these documents. The date is the effective date of the label version this page was built from.

Page last updated: 29 July 2026

Compiled by the HealthyStudy editorial team from FDA source documents. No medical reviewer is credited on this page, because none reviewed it.