Key takeaways

  • Orlistat is a generic prescription drug approved to help manage weight loss. It’s also available as the brand-name drug Xenical.
  • Orlistat comes as an oral capsule and is typically taken three times per day with a meal.
  • Side effects of Orlistat may include oily spotting on underwear, gas with discharge, and sudden urge to have a bowel movement.

Specifically, orlistat is used in adults and certain children to help:

  • with weight loss and weight management
  • reduce the risk of weight gain after weight loss

To learn more about orlistat’s uses, see the “Uses for orlistat” section.

Orlistat basics

Orlistat is a generic medication that’s also available as the brand-name drug Xenical. It’s also available over the counter under the brand name Alli.

Generic drugs are considered as safe and effective as the brand-name drug they’re based on, but they usually cost less.

Orlistat is used to help with weight loss and weight management in adults and in children ages 12 years and older. It should be used in combination with a reduced-calorie diet.

It’s indicated for people with a body mass index (BMI) of 30 kilograms per meters squared (kg/m2) with certain risk factors, including high blood pressure, diabetes, and high cholesterol.

Orlistat is also used to help reduce the risk of weight gain after weight loss.

Orlistat works by inhibiting digestive lipases (enzymes), which are responsible for breaking down fats in your digestive system. This prevents part of the fat in the food you eat from being absorbed, which leads to less fat staying in the body and more being excreted in the stool. By reducing fat absorption, orlistat helps with weight loss and weight management.

Like most drugs, orlistat may cause mild to serious side effects. The following lists contain some of the more common side effects orlistat may cause, but they don’t include all possible side effects.

Keep in mind that side effects of a drug can depend on:

  • your age
  • other health conditions you have
  • other medications you take

Your doctor or pharmacist can tell you more about the potential side effects of orlistat. They can also suggest ways to help reduce side effects.

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks and reviews side effects of the medication. Sharing your experience helps make medications safer for everyone by giving doctors and researchers more information about how the drug works in real life. If you develop a side effect while taking orlistat and want to tell the FDA about it, visit MedWatch or call 800-FDA-1088.

Mild side effects

Here’s a list of some of the mild side effects that orlistat can cause. To learn about other mild side effects, talk with your doctor or pharmacist, or read orlistat’s prescribing information.

Mild side effects of orlistat that have been reported include:

  • oily spotting on underwear
  • gas with discharge
  • sudden urge to have a bowel movement
  • oily or fatty stool
  • increase in bowel movements
  • difficulty controlling bowel movements
  • abdominal pain
  • nausea or vomiting
  • back pain
  • upper respiratory tract infections, such as the flu
  • headache
  • fatigue (low energy)

Mild side effects of many drugs may go away within a few days to a couple of weeks. But if they become bothersome, talk with your doctor or pharmacist.

Serious side effects

Serious side effects from orlistat can occur, but they aren’t common. If you have serious side effects from orlistat, call your doctor right away. If you think you’re having a medical emergency, you should call 911 or your local emergency number.

Serious side effects of orlistat that have been reported include:

  • liver problems
  • gallstones
  • increased levels of urinary oxalate, which may lead to kidney stones or damage
Allergic reaction

For some people, orlistat can cause an allergic reaction.

In general, symptoms of an allergic reaction can be mild or serious.

What might help

If you have mild symptoms of an allergic reaction, such as a mild rash, call your doctor right away. They may suggest a treatment to manage your symptoms and can determine whether you should continue orlistat treatment.

If you have symptoms of a severe allergic reaction, such as swelling or difficulty breathing, call 911 or your local emergency number right away. These symptoms could be life threatening and require immediate medical care.

If your doctor confirms you’ve had a serious allergic reaction to orlistat, they may have you switch to a different treatment.

The following information describes dosages that are commonly used or recommended for orlistat. However, be sure to take the dosage your doctor prescribes for you. Your doctor will determine the best dosage to fit your needs.

Form and strength

Orlistat is available as an oral capsule in one strength: 120 milligrams (mg).

Recommended dosage

Your doctor will prescribe the dosage of orlistat that’s right for you. Keep reading to learn more.

Dosage for weight loss and weight management

For treatment of weight loss and weight management, your doctor will likely prescribe one capsule three times per day with each main meal containing fat.

If you miss a meal or a meal does not contain fat, that dose of orlistat can be skipped.

Children’s dosage

Orlistat can be used in children age 12 years and older. The dosage of orlistat in children is the same as the adult dosage.

How to take

Your doctor will explain how you should take orlistat. They’ll also explain how much to take and how often. Be sure to follow your doctor’s instructions.

Orlistat can reduce the absorption of certain vitamins and medications. So, you’ll need to separate your dose of those medications from your dose of orlistat. Below are the recommendations about certain vitamins and medications:

  • Fat-soluble vitamins, such as vitamin A, D, E, and K, should be taken at least 2 hours before or after your dose of orlistat.
  • Cyclosporine should be taken 3 hours after your dose of orlistat.
  • Levothyroxine should be taken at least 4 hours apart from your dose of orlistat.

About taking orlistat

The following are some common questions about taking orlistat.

  • Can orlistat be chewed, crushed, or split? The manufacturer does not provide recommendations about chewing, crushing, or splitting orlistat. Talk with your doctor or pharmacist if you have trouble swallowing the oral capsules.
  • Should I take orlistat with food? Orlistat should be taken with a meal or up to 1 hour after the meal.
  • What if I miss a dose of orlistat? If you miss a dose of orlistat, skip the missed dose and take the next dose at its usual time. Orlistat needs to be taken with a meal containing fat, so there may be times when you’ll need to skip a dose. But you should not take two doses at once to make up for a missed dose. Doing so could raise your risk of side effects.
  • Will I need to use orlistat long term? Orlistat is typically used as a long-term treatment. If you and your doctor determine that it’s safe and effective for your condition, you’ll likely take it long term.

Overdose

Call your doctor if you think you’ve taken too much orlistat. You can also call 800-222-1222 to reach America’s Poison Centers or use its online resource. But if you have severe symptoms, immediately call 911 or your local emergency number. Or go to the nearest emergency room.

Orlistat can interact with several other medications. It can also interact with certain supplements.

Before taking orlistat, talk with your doctor and pharmacist. Tell them about all prescription, over-the-counter, and other drugs you take. Also tell them about any vitamins, herbs, or supplements you use. Sharing this information can help you avoid potential interactions.

Interactions with medications and supplements

The following table highlights medications, supplements, and foods that can interact with orlistat. This list does not contain all drugs that may interact with orlistat. If you have questions about interactions that may affect you, ask your doctor or pharmacist.

Medications that can interact with orlistat• cyclosporine
• levothyroxine
• warfarin
• amiodarone
• antiseizure drugs
• HIV drugs
Vitamins or supplements that can interact with orlistatfat-soluble vitamins, including vitamin A, D, E, and K

Orlistat and alcohol

Alcohol is not known to interact with orlistat.

Talk with your doctor to determine whether it’s safe for you to consume alcohol during orlistat treatment.

Whether you have health insurance or not, cost may be a factor when you’re considering orlistat. What you’ll pay for orlistat may depend on several things, such as your treatment plan and the pharmacy you use.

You can visit Optum Perks for price estimates of orlistat. These estimates are based on the use of Optum Perks coupons. Note: Optum Perks coupons cannot be used with insurance copays or benefits.

Optum Perks is owned by RVO Health. By clicking on this link, we may receive a commission. Learn more.

The following is important information to consider and discuss with your doctor or pharmacist before starting orlistat treatment.

Pregnancy and orlistat

Orlistat should not be taken during pregnancy. If you’re planning a pregnancy or can become pregnant, talk with your doctor before taking this drug. Your doctor may suggest birth control options to use during treatment with orlistat.

Orlistat and breastfeeding

It’s not known whether orlistat should be taken while breastfeeding. If you’re currently breastfeeding or planning to do so, talk with your doctor before taking this drug.

Before starting orlistat, discuss your health history with your doctor. This medication may not be right for you if you have certain medical conditions or other factors affecting your health. Be sure to talk with your doctor if any of the following apply to you:

Note: For more information about the potential negative effects of orlistat, see the “Side effects of orlistat” section.

Other drugs are available that can treat your condition. If you’d like to explore an alternative to orlistat, talk with your doctor. They can tell you about other medications that might work well for you.

The following drugs are similar to orlistat:

Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.