Dr Clare Morrison

Article by Dr Clare Morrison

Xenical vs Alli

Xenical and Alli are two kinds of oral weight loss medication, with Orlistat as their active ingredient. Both medications are designed to help dieters achieve their weight loss goals, and they both prevent the body from absorbing fat in exactly the same way. Xenical is the prescription dose (120mg) of Orlistat, while Alli is available over-the-counter and contains half the dose of prescription Xenical (60mg).

A noticeable change in your appearance can usually be seen within the first few weeks of treatment. Since Xenical is twice as strong as Alli, the results tend to be faster, although a more active lifestyle and adherence to a well-balanced, reduced-calorie diet will boost the effectiveness of both treatments.

It’s important you inform your doctor in the following cases:

  • You are pregnant, breastfeeding or trying for a baby
  • You have chronic malabsorption syndrome  (your body does not absorb food properly)
  • You have diabetes
  • You are taking other medicines or supplements (including those available to buy without prescription)
  • There is a history of cancer in your family, or a susceptibility

Xenical versus Alli: what’s the cost difference?

Although Alli is slightly cheaper, it should also be noted that Alli (Orlistat 60mg) is half the strength of Xenical (Orlistat 120mg).

Our Prices Generic Orlistat 120mg Xenical (Orlistat 120mg) Alli (Orlistat 60mg)
Four weeks (84 tablets)  £64.99    £68.99 £49.99

Xenical versus Alli: what are the dosage differences? 

Alli has chewable tablets which can be taken without water, as well as the more traditional tablets. Xenical is taken with water alongside any meals which contain fat. You should take Xenical in conjunction with a weight-reducing calorie diet.

Xenical vs Alli: which treatment is the most effective?

An important part of your decision to lose weight with Orlistat is knowing which treatment is the most effective. Xenical (120mg) may provide positive results within just three months; however, its strength means that it is only available on prescription. Alli, which is available over the counter, contains less Orlistat (60mg), and so noticeable weight loss results with Alli may take a little longer.

A higher dose of Orlistat may be more effective in helping you lose weight quickly, but what works for some is not always appropriate for others. Consult with your doctor or pharmacist to find the treatment that’s right for you.

Remember that making healthy lifestyle choices greatly increases the effectiveness of Xenical and Alli, so keeping active and adhering to a well-balanced diet will help you achieve the best results!


Dr Clare Morrison
Dr Clare Morrison
Experienced General Practitioner in Hampshire since 1995, with particular interest in Nutrition, Obesity and Smoking Cessation.
Originally published September 24 2014, updated July 08 2019