Xenical vs. Alli for Weight Loss: 5 Differences Between Prescription and Over-the-Counter Orlistat

If you’ve been considering giving weight-loss pills a try, you may have come across orlistat. It’s the active ingredient in both Xenical and Alli. These medications help promote weight loss by blocking your body’s ability to absorb fat.

But why are there two versions of orlistat? To start, one requires a prescription and the other doesn’t. Here are five ways Xenical and Alli compare.

1. Xenical requires a prescription, while Alli is over the counter

Xenical, first FDA approved in 1999, is a prescription medication. To get it, you need to talk with a licensed healthcare professional, who will determine if it’s right for you. But in 2007, orlistat, Xenical’s active ingredient, became available over the counter (OTC) as Alli, making it more accessible. You can purchase Alli directly from pharmacies without a prescription.

2. Xenical can be used in adolescents, while Alli is for adults only

Xenical and Alli are both approved for use in adults. But Xenical is also approved for adolescents ages 12 and older. It’s one of a few weight-loss medications approved for this age group. Other examples include Qsymia (phentermine / topiramate ER), Saxenda (liraglutide), and Wegovy (semaglutide). Alli hasn’t been studied for safety and effectiveness in adolescents.

3. Xenical and Alli have slightly different approved uses

Both Xenical and Alli can help you lose weight when paired with a reduced-calorie diet. But they have slightly different approved uses. 

Xenical is approved for weight loss and maintenance, as well as helping to prevent regaining weight after weight loss. Xenical eligibility is based on body mass index (BMI). It’s specifically approved for people with a BMI of at least 30 kg/m2, or at least 27 kg/m2 with other risk factors, including weight-related health conditions such as high blood pressure.

Since Alli is an OTC product, its use is a bit more general. It can help promote weight loss in adults who are considered overweight. There aren’t any specific eligibility criteria based on BMI or health conditions.

4. Xenical contains a higher dose of orlistat than Alli

The most significant difference between Xenical and Alli is the dosage. Both medications are taken 3 times daily before fat-containing meals. But Xenical’s dosage is twice as much as Alli. Xenical is available as 120 mg oral capsules. Alli is available as 60 mg capsules.

Studies show that the 60 mg orlistat dose is about 85% as effective as the 120 mg dose. Both medications can cause similar side effects, such as loose or oily stools. But some people may tolerate the 60 mg dose better. A healthcare professional can help you figure out which option is best for you.

5. Xenical has an authorized generic, while Alli is a brand-name only product

As a prescription medication, Xenical is available as both a brand-name product and an authorized generic called orlistat. The authorized generic is the exact same medication as Xenical, but without the brand name on the label. It’s also typically sold at a lower price. Alli is only available as a brand-name product.

GoodRx can help make either medication more affordable. Since Alli is OTC, you’ll need a prescription from a healthcare professional to use a GoodRx discount.

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Written by:

Brian Leonard, PharmD, BCACP, BCGP

Brian Leonard earned his doctorate in pharmacy from the University of Florida College of Pharmacy and is board certified in Ambulatory Care and Geriatric Pharmacy.

Edited by:

Alyssa Billingsley, PharmD

Alyssa Billingsley, PharmD, is the director of pharmacy content for GoodRx. She has over a decade of experience as a pharmacist and has worked in clinical, academic, and administrative roles.

Reviewed by:

Austin Ulrich, PharmD, BCACP

​​Austin Ulrich, PharmD, BCACP, is a board-certified ambulatory care clinical pharmacist. Ulrich’s experience includes direct patient care in hospital and community pharmacies.

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