Orlistat (By mouth)


Orlistat (OR-li-stat)

Helps you reach and maintain a healthy weight.

Brand Name(s)

Xenical, Alli

There may be other brand names for this medicine.

When This Medicine Should Not Be Used

Do not use this medicine if you have had an allergic reaction to orlistat, if you have gallbladder disease, or if you have a disorder that keeps you from absorbing or digesting food. Do not use this medicine if you are pregnant.

How to Use This Medicine


  • Your doctor will tell you how much of this medicine to use and how often. Do not use more medicine or use it more often than your doctor tells you to.
  • Take this medicine during each main meal or up to 1 hour after a meal.
  • This medicine comes with patient instructions. Read and follow these instructions carefully. Ask your doctor or pharmacist if you have any questions.

If a dose is missed:

  • If you miss a meal or eat a fat-free meal, you can skip your dose of the medicine.
  • If you forget to take the medicine with a meal, you may take it up to 1 hour after the meal. If more than 1 hour has passed, do not take the medicine. Wait until it is time for your next dose to take the medicine. Do not use extra medicine to make up for a missed dose.

How to Store and Dispose of This Medicine

  • Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light.
  • Ask your pharmacist, doctor, or health caregiver about the best way to dispose of any outdated medicine or medicine no longer needed.
  • Keep all medicine away from children and never share your medicine with anyone.

Drugs and Foods to Avoid

Ask your doctor or pharmacist before using any other medicine, including over-the-counter medicines, vitamins, and herbal products.

  • Make sure your doctor knows if you take cyclosporine (Gengraf®, Neoral®, Sandimmune®). Cyclosporine must be used at least 3 hours before or 3 hours after you use orlistat.
  • If you use multivitamins, take them at least 2 hours before or 2 hours after you take orlistat.
  • Tell your doctor if you also use levothyroxine (Levothroid®, Levoxyl®, Synthroid®). Levothyroxine must be used at least 4 hours before or 4 hours after you take this medicine.
  • Your doctor should know if you are also using medicine to treat diabetes (such as insulin, glyburide, glipizide, metformin, Glucophage®, or Glucotrol®), a blood thinner (such as warfarin, Coumadin®), or any other medicines to help you lose weight.

Warnings While Using This Medicine

  • Using this medicine while you are pregnant can harm your unborn baby. Use an effective form of birth control to keep from getting pregnant. If you think you have become pregnant while using the medicine, tell your doctor right away.
  • Make sure your doctor knows if you are breastfeeding, or if you have kidney problems (such as kidney stones), liver disease, underactive thyroid, or an eating disorder (such as anorexia or bulimia).
  • Make sure your doctor knows if you have diabetes. He may change your diabetes medicine if you lose weight.
  • Bowel side effects can be worse if you eat a meal that is more than 30% fat. This medicine prevents you from absorbing some of the fat from food. The undigested fat comes out in your bowel movements. To reduce side effects, divide your daily intake of fat evenly over your 3 main meals each day.
  • Carefully follow your doctor's instructions for a well-balanced, reduced-calorie meal plan.
  • Take a multivitamin supplement that contains vitamins D, E, and K, and beta-carotene. You may need this because orlistat keeps you from absorbing some of the vitamins from food.
  • Stop using this medicine and check with your doctor right away if you have pain or tenderness in the upper stomach, unusual itching, yellowing of the eyes or skin, dark urine, loss of appetite, or pale stools. These may be signs of a serious liver problem.
  • Weight loss with this medicine may increase your risk for gallstones. Check with your doctor right away if you have severe stomach pain with nausea and vomiting.
  • Your doctor will need to check your progress at regular visits while you are using this medicine. Be sure to keep all appointments.Blood and urine tests may be needed to check for unwanted effects.

Possible Side Effects While Using This Medicine

Call your doctor right away if you notice any of these side effects:

  • Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness, trouble breathing
  • Change in how much or how often you urinate, or painful urination
  • Dark-colored urine or pale stools
  • Nausea, vomiting, loss of appetite, or pain in your upper stomach
  • Red or dark brown urine
  • Severe diarrhea
  • Severe stomach pain with nausea and vomiting
  • Sharp back pain just below the ribs
  • Swelling of your legs and feet
  • Yellowing of your skin or the whites of your eyes

If you notice these less serious side effects, talk with your doctor:

  • Fever, chills, cough, runny or stuffy nose, sore throat, and body aches
  • Increases in bowel movements, loss of bowel control, or the need to have a bowel movement right away
  • Passing gas with oily discharge
  • Passing oil or fat with your bowel movements or between bowel movements

If you notice other side effects that you think are caused by this medicine, tell your doctor

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088

Version Info

  • Last Reviewed on 06/12/2013

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This page was last updated: June 18, 2013

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