Description and Brand Names

Drug information provided by: Merative, Micromedex®

US Brand Name

  1. Alli
  2. Xenical


Orlistat is used with a reduced-calorie diet and regular exercise to help with weight loss. This medicine is used in people with overweight or obesity.

This medicine is available both over-the-counter (OTC) and with your doctor's prescription.

This product is available in the following dosage forms:

  • Capsule

Before Using

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For this medicine, the following should be considered:


Tell your doctor if you have ever had any unusual or allergic reaction to this medicine or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.


Appropriate studies performed to date have not demonstrated pediatric-specific problems that would limit the usefulness of orlistat in teenagers. Safety and efficacy have not been established in children younger than 12 years of age.


Appropriate studies performed to date have not demonstrated geriatric-specific problems that would limit the usefulness of orlistat in the elderly.


There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.

Drug Interactions

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking this medicine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

  • Abacavir
  • Acenocoumarol
  • Apixaban
  • Ardeparin
  • Argatroban
  • Atazanavir
  • Bivalirudin
  • Carbamazepine
  • Certoparin
  • Clobazam
  • Clonazepam
  • Clorazepate
  • Cobicistat
  • Cyclosporine
  • Dabigatran Etexilate
  • Dalteparin
  • Danaparoid
  • Darunavir
  • Desirudin
  • Diazepam
  • Didanosine
  • Edoxaban
  • Efavirenz
  • Elvitegravir
  • Emtricitabine
  • Enoxaparin
  • Eslicarbazepine Acetate
  • Ethosuximide
  • Ethotoin
  • Etravirine
  • Ezogabine
  • Felbamate
  • Fondaparinux
  • Fosamprenavir
  • Fosphenytoin
  • Gabapentin
  • Gabapentin Enacarbil
  • Heparin
  • Indinavir
  • Lacosamide
  • Lamivudine
  • Lamotrigine
  • Lepirudin
  • Levetiracetam
  • Levoketoconazole
  • Lopinavir
  • Lorazepam
  • Methotrexate
  • Methsuximide
  • Midazolam
  • Nadroparin
  • Nelfinavir
  • Nevirapine
  • Oxcarbazepine
  • Parnaparin
  • Perampanel
  • Phenindione
  • Phenobarbital
  • Phenprocoumon
  • Phenytoin
  • Piracetam
  • Pregabalin
  • Primidone
  • Protein C
  • Raltegravir
  • Reviparin
  • Rilpivirine
  • Ritonavir
  • Rivaroxaban
  • Rufinamide
  • Saquinavir
  • Stavudine
  • Stiripentol
  • Telaprevir
  • Tenofovir
  • Tiagabine
  • Tinzaparin
  • Tipranavir
  • Topiramate
  • Triheptanoin
  • Valproic Acid
  • Venlafaxine
  • Vigabatrin
  • Warfarin
  • Zidovudine
  • Zonisamide

Using this medicine with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

  • Linoleic Acid

Other Interactions

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.

Other Medical Problems

The presence of other medical problems may affect the use of this medicine. Make sure you tell your doctor if you have any other medical problems, especially:

  • Diabetes or
  • Hypothyroidism (underactive thyroid)—Use with caution. May increase risk for more serious side effects.
  • Eating disorders (eg, anorexia nervosa or bulimia) or
  • HIV infection or
  • Hyperoxaluria (high oxalic acid in the urine), history of or
  • Kidney failure or
  • Kidney stones or
  • Liver disease—Use with caution. May make these conditions worse.
  • Gallbladder problems or
  • Malabsorption syndrome (trouble digesting food)—Should not be used in patients with these conditions.

Proper Use

Take this medicine only as directed by your doctor. Do not take more of it, do not take it more often, and do not take it for a longer time than your doctor ordered.

This medicine comes with a patient information insert. Read and follow the instructions in the insert carefully. Talk to your doctor if you have any questions.

Orlistat prevents the absorption of some of the fat you eat. You should take it with liquids during the meal or up to 1 hour after eating. If you occasionally miss a meal or eat a meal that contains no fat, you should skip the dose of orlistat.

Because orlistat may decrease the amount of some vitamins that your body absorbs from food, you will need to take a multivitamin supplement once a day. Take the vitamin supplement at least 2 hours before or after taking orlistat. You may also take your multivitamin supplement at bedtime.

When using orlistat, your diet should contain no more than 30% of calories as fat. More fat in your diet will increase the side effects of this medicine. Your diet should be nutritionally balanced, and your daily intake of fat, carbohydrates, and protein should be distributed over three main meals.

Carefully follow your doctor's instructions for a reduced-calorie diet plan and regular exercise. Talk with your doctor before starting any exercise program.

If you are taking cyclosporine, take it at least 3 hours before or after taking this medicine. Levothyroxine should be taken 4 hours before or after taking orlistat.

Take a multivitamin supplement that contains vitamins A, D, E, and K with beta carotene at least 2 hours before or after taking this medicine. Orlistat keeps your body from absorbing some of the vitamins from food.


The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

  • For oral dosage form (capsules):
    • For treatment of obesity:
      • Adults and teenagers—120 milligrams (mg) 3 times a day with meals containing fat.
      • Children younger than 12 years of age—Use and dose must be determined by your doctor.

Missed Dose

If you miss a dose of this medicine, skip the missed dose and go back to your regular dosing schedule. Do not double doses.


Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.

Keep out of the reach of children.

Do not keep outdated medicine or medicine no longer needed.

Ask your healthcare professional how you should dispose of any medicine you do not use.


It is very important that your doctor check your or your child's progress at regular visits, to make sure that this medicine is working properly. Blood and urine tests may be needed to check for unwanted effects.

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 this medicine, tell your doctor right away.

For patients with diabetes: Weight loss may result in an improvement in your condition, and your doctor may need to change your dose of oral diabetes medicine or insulin.

Check with your doctor right away if you have pain or tenderness in the upper stomach, pale stools, dark urine, loss of appetite, nausea, unusual tiredness or weakness, or yellow eyes or skin. These could be symptoms of a serious liver problem.

This medicine may increase your risk of having kidney stones. Check with your doctor right away if you or your child have blood in the urine, nausea and vomiting, pain in the groin or genitals, or sharp back pain just below the ribs.

This medicine may increase your risk of gallbladder problems (eg, cholelithiasis). Check with your doctor right away if you or your child have gaseous stomach pain, recurrent fever, stomach fullness, or yellow eyes or skin.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.

Side Effects

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur:

More common

  1. Bladder pain
  2. body aches
  3. chills
  4. cough
  5. diarrhea
  6. difficulty with breathing
  7. ear congestion
  8. fever
  9. general feeling of discomfort or illness
  10. headache
  11. loss of appetite
  12. loss of voice
  13. lower back or side pain
  14. muscle aches and pains
  15. nasal congestion
  16. nausea
  17. runny nose
  18. shivering
  19. sneezing
  20. sore throat
  21. sweating
  22. trouble sleeping
  23. unusual tiredness or weakness
  24. vomiting

Less common

  1. Chest tightness
  2. tooth or gum problems
  3. trouble breathing


  1. Bloody or cloudy urine
  2. change in hearing
  3. contagious diarrhea
  4. dark urine
  5. difficult or painful urination
  6. earache
  7. fast heartbeat
  8. frequent urge to urinate
  9. general tiredness and weakness
  10. hives
  11. hoarseness
  12. irritation
  13. itching
  14. joint pain, stiffness, or swelling
  15. large, hive-like swelling on the face, eyelids, lips, tongue, throat, hands, legs, feet, or sex organs
  16. light-colored stools
  17. noisy breathing
  18. rash
  19. redness of the skin
  20. skin blisters
  21. swelling of the eyelids, face, lips, hands, or feet
  22. trouble swallowing
  23. upper right abdominal or stomach pain
  24. yellow eyes and skin

Incidence not known

  1. Anxiety
  2. bloating
  3. blurred vision
  4. cold sweats
  5. coma
  6. confusion
  7. constipation
  8. cool, pale skin
  9. depression
  10. dizziness
  11. dry skin and hair
  12. feeling cold
  13. hair loss
  14. hoarseness or husky voice
  15. increased hunger
  16. indigestion
  17. loss of appetite
  18. muscle cramps and stiffness
  19. nervousness
  20. nightmares
  21. pains in the stomach, side, or abdomen, possibly radiating to the back
  22. seizures
  23. weight gain

Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

  1. Back pain
  2. difficulty with moving
  3. gas with leaky bowel movements
  4. inability to hold bowel movement
  5. increases in bowel movements
  6. loss of bowel control
  7. oily bowel movements
  8. oily spotting of underclothes
  9. stomach pain or discomfort

Less common

  1. Itching of the vagina or genital area
  2. menstrual changes
  3. pain during sexual intercourse
  4. rectal pain or discomfort
  5. thick, white vaginal discharge with no odor or with a mild odor

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

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