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    What's the difference between Orlistat, Xenical and Alli?

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      We all know that being overweight is unhealthy, but for many people, losing weight can be a real challenge. Even with the right diet and exercise plan in place, shedding enough pounds to get down to a healthy size can be a slow and demoralising process. That’s why many people who are looking to get fitter and healthier turn to a safe weight loss tablet like Orlistat, Xenical or Alli.

      If you’re an adult over 18 with a BMI of 28 or higher, LloydsPharmacy Online Doctor can safely prescribe or recommend one of these weight loss tablets. Read on to find out which type might suit you best.

      How weight loss tablets work

      The first thing to know is that Orlistat, Xenical and Alli all contain exactly the same active ingredient, orlistat. That means they all work in the same way.

      Orlistat works by preventing some of the fat you consume from being digested. It does this by attaching to the enzymes in your digestive system that break down fat, preventing them from working properly. As a result, the fat that cannot be digested is eliminated from your body in your stools. This helps you to lose weight.

      Although all three tablets work in this way, there are some key differences between them, which we have detailed below.


      Orlistat is both the name of the active drug in these weight loss tablets, and therefore, the generic label for the medicine. A generic label is used in place of a brand name and usually indicates a cheaper price. The generic version of Nurofen, for instance, is known as ibuprofen (because it contains the active ingredient ibuprofen) and is usually cheaper than Nurofen.

      Orlistat is a prescription treatment for people considered obese. It comes in tablet sizes of 120mg and, when taken correctly, prevents around 1/3 of the fat you consume from being digested. One tablet should be taken with each meal (i.e. you should take three tablets a day). You can take the tablet just before you eat, during your meal, or up to one hour after you have eaten.

      Remember that Orlistat capsules work by affecting the way in which fat is digested; if you skip a meal, you don’t need to take a tablet, and if you eat a meal that contains zero fat, you don’t need to take a tablet either.

      Usually, Orlistat will be taken for 12 weeks; during this time, you should expect to lose about 5% of your body weight, however this will be dependent upon other lifestyle factors. If you make an effort to eat healthily with sensible portion sizes and exercise while you are taking Orlistat you should see better results.

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      Xenical works in exactly the same way as orlistat. It contains orlistat as its active ingredient, comes in a tablet size of 120mg and works by preventing 1/3 of your fat intake from being digested.

      The difference between orlistat and Xenical is that orlistat is the generic version of the medicine, while Xenical is branded. That means that Xenical is more expensive than Orlistat and better known as a weight loss tablet. Xenical should be taken in exactly the same way as orlistat.


      The third weight loss medicine containing orlistat is Alli, which is available over the counter in high street pharmacies. It does not require a prescription because it contains half the dosage of orlistat or Xenical (i.e. 60mg).

      Alli works in the same way as Orlistat and Xenical, by preventing your body from digesting some of the fat you consume. However, because the dosage is smaller, it typically only prevents around 1/4 of dietary fat from being digested.

      One Alli tablet should be taken three times a day with meals, as with orlistat and Xenical. As part of a healthy eating and fitness regime, Alli is thought to help you lose one extra pound for every two pounds you lose naturally.

      In summary…

      • Orlistat (120mg) is a generic prescription treatment that prevents 1/3 of dietary fat from being digested. It is cheaper than Xenical, but more expensive than Alli.
      • Xenical (120mg) is a branded prescription treatment that prevents 1/3 of dietary fat from being digested. It is the best-known weight loss tablet, but also the most expensive.
      • Alli (60mg) is an over-the-counter treatment that prevents 1/4 of dietary fat from being digested. It is not as strong as Xenical or orlistat but is the cheapest tablet overall.

      Warnings and side effects

      None of these tablets should be taken if you are:

      • Pregnant or breastfeeding
      • Under the age of 18
      • Have a BMI under 28

      Side effects of all three tablets are similar, the most common being:

      • Flatulence
      • Sudden bowel movements
      • Oily stools

      Some people also experience some abdominal pain, diarrhoea, anxiety and incontinence. If you experience any side effects that are prolonged or troublesome you should speak to your pharmacist or doctor.

      How to buy Orlistat, Xenical or Alli

      LloydsPharmacy Online Doctor can prescribe Orlistat and Xenical to people with a BMI over 28, provided that they have filled out a confidential questionnaire detailing their medical history and any current medications. In our weight loss clinic, both Orlistat and Xenical come in 28 or 84-day courses (supplying three tablets per day).

      Orlistat is available on the NHS, but is typically only prescribed to people with a BMI over 28 who have exhausted other weight loss techniques.

      For more information on losing weight, visit our weight loss pills page.

      From the LloydsPharmacy site, Alli is available in single, twin or triple packs of 84-day courses. Click here to learn more.

      LloydsPharmacy also offers a Medicated Weight Loss service. This service includes ongoing advice and support alongside a prescribed medication, which is a daily injection. Find out more. 

      You can also read more about losing weight healthily here.

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      LloydsPharmacy Online Doctor

      This service operates in the United Kingdom only

      LloydsPharmacy Online Doctor

      This service operates in the United Kingdom only

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