What is Alli: Uses, Warnings & Interactions

Updated May 14, 2025  •  Published Dec 30, 2020

Alli overview

BRAND NAMES:

  • Xenical, Alli

Generic Names:

  • Alli

Uses:

  • Helps you reach and maintain a healthy weight.

Therapeutic Classes:

  • Dietary Fat Absorption Inhibitor

Forms:

  • Capsule

How it’s taken:

  • By mouth

What is Alli used for?

What form(s) does Alli come in

  • Capsule

What are common Alli doses?

  • Bottle 90 Capsules

  • Bottle 120 Capsules

  • Bottle 170 Capsules

Common Alli prescriptions

  • Alli
    120 capsules bottle

  • Alli
    170 capsules bottle

  • Alli
    21 capsules bottle

  • Alli
    60 capsules bottle

  • Alli
    90 capsules bottle

How to take Alli

  • Follow the instructions on the medicine label if you are using this medicine without a prescription.

  • Take this medicine during each main meal or up to 1 hour after a meal.

  • This medicine works by keeping your body from absorbing some of the fat in your meal. If you skip a meal or eat a meal that does not contain any fat, do not take the medicine. It will not do anything.

  • Eat a well-balanced, reduced-calorie meal plan. Divide the amount of protein, fats, and carbohydrates evenly among your 3 daily meals.

  • Read and follow the patient instructions that come with this medicine. Talk to your doctor or pharmacist if you have any questions.

  • Missed dose: You may take this medicine up to 1 hour after the meal. If more than 1 hour has passed, skip your dose and just take your next dose with your next meal. Do not use extra medicine to make up for a missed dose.

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

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

  • Eat a well-balanced, reduced-calorie meal plan. Divide the amount of protein, fats, and carbohydrates evenly among your 3 daily meals.

  • This medicine works by keeping your body from absorbing some of the fat in your meal. If you skip a meal or eat a meal that does not contain any fat, do not take the medicine. It will not do anything.

  • Missed dose: You may take this medicine up to 1 hour after the meal. If more than 1 hour has passed, skip your dose and just take your next dose with your next meal. Do not use extra medicine to make up for a missed dose.

  • Take this medicine during each main meal or up to 1 hour after a meal.

  • Follow the instructions on the medicine label if you are using this medicine without a prescription.

  • Read and follow the patient instructions that come with this medicine. Talk to your doctor or pharmacist if you have any questions.

What to do if you miss a dose of Alli

Alli contraindications

  • This medicine is not right for everyone. Do not use it if you had an allergic reaction to orlistat, or if you are pregnant.

Alli warnings

  • It is not safe to take this medicine during pregnancy. It could harm an unborn baby. Tell your doctor right away if you become pregnant.

  • Tell your doctor if you are breastfeeding, or if you have kidney disease, liver disease, digestion problems, diabetes, gallbladder problems, heart rhythm problems, seizures, thyroid problems, or an eating disorder (such as anorexia or bulimia).

  • This medicine may cause the following problems:Liver damageHigher risk of kidney stonesGallbladder or bile flow problems, gallstones

  • Bowel side effects can be worse if you eat a meal that is more than 30% fat. 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.

  • Take a multivitamin supplement that contains vitamins A, D, E, and K with beta carotene. Orlistat keeps your body from absorbing some of the vitamins from food.

  • Keep all medicine out of the reach of children. Never share your medicine with anyone.

Alli interactions

  • Keep all medicine out of the reach of children. Never share your medicine with anyone.

  • Some foods and medicines can affect how orlistat works. Tell your doctor if you use any of the following:AmiodaroneBlood thinner (including warfarin)Medicine to treat diabetes (including insulin)Medicine to treat HIV/AIDS (including atazanavir, emtricitabine, emtricitabine/efavirenz/tenofovir disoproxil fumarate, lopinavir/ritonavir, ritonavir, tenofovir disoproxil fumarate)Medicine to treat seizures

  • Cyclosporine: Take at least 3 hours after you take orlistat.

  • Levothyroxine: Take at least 4 hours before or after you take orlistat.

  • Multivitamin supplement: Take at least 2 hours before or after you take orlistat, such as at bedtime.

  • Take a multivitamin supplement that contains vitamins A, D, E, and K with beta carotene. Orlistat keeps your body from absorbing some of the vitamins from food.

Alli side effects

Serious Side Effects

  • Severe stomach pain with nausea and vomiting

  • Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness, trouble breathing

  • Dark urine or pale stools, nausea, vomiting, loss of appetite, stomach pain, yellow skin or eyes

  • Decrease in how much or how often you urinate, sharp back pain just below the ribs, or painful urination

  • Severe diarrhea

Less Serious Side Effects

  • Increases in bowel movements, loss of bowel control, or the need to have a bowel movement right away

  • Passing oil or fat with your bowel movements or between bowel movements

  • Passing gas with oily discharge

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