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Overview: Orlistat is used for weight loss. It decreases the amount of fat you absorb from food. The most common side effects include oily poop, gas, increased pooping frequency, and decreased control of pooping. Eating a meal that has a lot of fat may increase your risk for side effects. Orlistat can decrease the absorption of certain vitamins. Talk to your health care provider about which multivitamin to take while taking orlistat.

Uses

What is orlistat used for?

Orlistat is commonly used to help people with obesity or people who are overweight lose weight. 

Orlistat may also be used for other conditions as determined by your health care provider.

How does orlistat work (mechanism of action)?

Orlistat helps with weight loss by reducing the amount of fat your body absorbs from food.

How is orlistat supplied (dosage forms)?

Brands and other names

  • Alli
  • Xenical

Dosage forms and strengths

  • 60 mg, 120 mg oral capsules

How should I store orlistat?

Orlistat should be stored tightly closed at room temperature, between 68 F to 77 F (20 C to 25 C). It can be exposed to temperatures between 59 F to 86 F (15 C to 30 C) for shorter periods of time, such as when transporting it. Store in a cool, dry place. Protect from light and moisture. 

Side Effects

What are the most common side effects of orlistat?

The most common side effects of orlistat are listed below. Tell your health care provider if you have any of these side effects that bother you.

  • Gas
  • Oily leakage from anus 
  • Oily poop
  • Increased pooping frequency
  • Decreased ability to control bowel movements

There may be other side effects of orlistat that are not listed here. Contact your health care provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088. In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of orlistat?

While less common, the most serious side effects of orlistat are described below, along with what to do if they happen.

Liver Damage. Liver damage, also called hepatotoxicity, can happen when taking orlistat. Call your health care provider right away if you have any of the following symptoms of liver damage.

  • Nausea or vomiting
  • Stomach or belly pain
  • Fever
  • Weakness or unusual tiredness
  • Itching
  • Loss of appetite
  • Light-colored poop
  • Dark-colored urine (pee)
  • Your skin or the whites of your eyes turning yellowish in color (also called jaundice)

Kidney Problems. Orlistat may cause kidney stones and kidney damage that can lead to renal failure. Keep all appointments to have your blood checked. Tell your health care provider right away if you develop any of the following symptoms.

  • Decreased or no urine (pee)
  • Nausea or vomiting
  • Loss of appetite
  • Pain when you pee
  • Increased need to pee
  • Blood in your pee (pee may look pink, red, or brown)
  • Back, belly or groin pain
  • Swelling of your legs or feet

Gallbladder Problems. Taking orlistat may cause cholelithiasis, also known as gallstones. Call your health care provider right away if you have any of the following symptoms.

  • Pain in your upper stomach area
  • Nausea or vomiting

Severe Allergic Reactions. Orlistat may cause allergic reactions, which can be serious. Stop taking orlistat and get help right away if you have any of the following symptoms of a serious allergic reaction.

  • Breathing problems or wheezing
  • Racing heart
  • Fever or general ill feeling
  • Swollen lymph nodes
  • Swelling of the face, lips, mouth, tongue, or throat
  • Trouble swallowing or throat tightness
  • Itching, skin rash, or pale red bumps on the skin called hives
  • Nausea or vomiting
  • Dizziness, feeling lightheaded, or fainting
  • Stomach cramps
  • Joint pain

Warnings & Precautions

Who should not use orlistat?

Allergies to Ingredients. People who are allergic to any of the following should not take orlistat.

  • Alli
  • Orlistat
  • Xenical
  • Any of the ingredients in the specific product

Your pharmacist can tell you all of the ingredients in the specific orlistat products they stock.

Pregnancy. Do not take orlistat if you are pregnant. If you become pregnant, contact your health care provider right away. See the Pregnancy section for more details.

Problems Absorbing Food. Orlistat should not be used if you have malabsorption syndrome. 

Gallbladder Problems. Orlistat should not be used by people with cholestasis, a problem where a substance called bile does not flow well. 

What should I know about orlistat before using it?

Take each dose of orlistat with a fat-containing meal or up to one hour after a fat-containing meal. Any meal that is high in fat (more than 30% of calories from fat) can increase your risk for side effects. If you skip a meal or if a meal does not contain fat, you can skip that dose of orlistat. 

Orlistat can decrease the absorption of certain vitamins and nutrients. Talk to your health care provider about which multivitamin to take while on this medicine. The multivitamin should be taken two hours before or after a dose of orlistat. 

Keep orlistat out of the reach of children.

What should I tell my health care provider before using orlistat?

Tell your health care provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them determine if orlistat is right for you.

In particular, make sure that you discuss any of the following.

Other Current and Past Health Conditions. Tell your health care provider if you have any of the following.

  • Liver problems
  • Kidney problems, including kidney stones
  • Thyroid problems
  • Eating disorder like anorexia or bulimia
  • Diabetes
  • History of seizures
  • Abnormal heart rate or rhythm
  • HIV or AIDS
  • Organ transplant
  • Pancreatitis

Other Medicines and Supplements. Orlistat may interact with other medicines and supplements. Before taking orlistat, tell your health care provider about any prescription or other-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. See the Interactions section for more details. 

Pregnancy. Do not take orlistat if you are pregnant or plan to get pregnant. It is not known if or how orlistat could affect pregnancy or harm an unborn baby. However, weight loss is not recommended during pregnancy, even if you are already overweight. If you become pregnant while taking orlistat, contact your health care provider.

Breastfeeding. It is not known if orlistat passes into breast milk. Tell your health care provider if you are breastfeeding or plan to breastfeed. Your health care provider will advise you if you should take orlistat while breastfeeding.

Interactions

Does orlistat interact with foods or drinks?

Orlistat should be taken with or within one hour of meals. Because orlistat reduces the amount of fat your body absorbs from food, you can skip your dose of orlistat if a meal is skipped or if the meal has very little fat in it.

Drinking alcohol does not affect how well orlistat works. However, the risk of liver damage may be increased if you drink alcohol while taking this medicine. It is best to limit the amount of alcohol you drink while taking orlistat.

Does orlistat interact with other medicines (drug interactions)?

Always tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.

In particular, make sure that you discuss if you are using any of the following before taking orlistat.

  • Cyclosporine (Gengraf, Neoral, Sandimmune, and others), which is a medicine that suppresses your immune system
  • Levothyroxine, which is a medicine used to raise thyroid hormone levels
  • Warfarin, which is a blood thinner
  • Amiodarone (Pacerone and others), which is a medicine used for an irregular heart rhythm
  • Any medicine for seizures, such as carbamazepine, phenobarbital, or phenytoin
  • A medicine for HIV or AIDS
  • A vitamin or supplement

This may not be a complete list of medicines that can interact with orlistat. Always check with your health care provider.

Does interact with other drugs you are taking?

Enter your medication into the WebMD interaction checker

Overdose/Missed Dose

What should I do if I accidentally use too much orlistat?

If you or someone else has used too much orlistat, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.

What should I do if I miss a dose of orlistat?

This medicine is only to be taken with a fat-containing meal. If you eat a fat-containing meal and miss a dose, take it as soon as you remember if it is within one hour of your meal. The medicine will not work well if you take it more than one hour after eating. Do not take double or extra doses.