HomeThe Complete Guide to OrlistatHealth Hub
Weight Management

The Complete Guide to Orlistat

Pharmacy2U Team | minute read
weightloss image, healthy food vegetables, meat and fruit

Orlistat is an active ingredient used in Xenical, a weight management medication that is available in the UK via a prescription. Orlistat works by blocking the absorption of some of the fat you eat, helping you excrete it from your body rather than storing it. 

In this guide, we will explore everything you need to know about Orlistat including how it works, its effectiveness, the potential side effects, and whether it is suitable for you.

How does Orlistat work?

Orlistat belongs to the ‘lipase inhibitors’ class of medication. Lipase is an enzyme produced by your pancreas and intestines that assists in breaking down dietary fats into smaller components that your body can absorb. Orlistat works by blocking the action of lipase, preventing around a third of the fat you eat from being absorbed. The undigested fat is then excreted in your stools.

How effective is Orlistat?

Studies suggest that people taking orlistat, alongside a calorie-controlled diet and physical exercise program, may lose an average of 0.94kg per month

3 months after being prescribed orlistat, you should see at least a reduction of around 5% of your body weight. If you haven’t lost that much weight within that time, your doctor may want to review your treatment choices to explore a more effective weight management option for you.

It’s important to remember that:

  • Orlistat is most effective for those who are overweight or obese with a BMI of 30 or over. People with a lower BMI may see minimal effects.

  • Orlistat works most effectively in combination with a healthy lifestyle which includes a calorie-controlled diet and physical exercise.

Orlistat’s effects tend to be modest and should be viewed as a support tool for long-term weight management.

What are the side effects of Orlistat?

The most common side effects of orlistat are directly related to its mechanism of action which affects how your body processes fat. These side effects are usually mild and may improve as your body adjusts to the treatment. 

Common side effects include:

  • Oily stools or discharge

  • Increased urgency to have bowel movement

  • Stomach pain or discomfort

  • Gas with oily discharge

Less common side effects include:

  • Rectal irritation

  • Irregular menstrual periods

  • Fatigue 

  • Back pain 

  • Difficulty sleeping

Your GP can discuss side effects with you and give you tailored advice before prescribing a weight loss treatment that contains orlistat. It is also possible that orlistat can interfere with the absorption of fat-soluble vitamins such as A, D, E and K - and your GP or Pharmacist may advise taking a multivitamin supplement.

Considerations before taking Orlistat

Orlistat isn’t suitable for everyone and your doctor will only recommend it if they think it is right for you. 

Here are some things to consider before using orlistat:

  • Allergies: if you’re allergic to any of the ingredients found within Xenical, you shouldn’t take it.

  • Medical conditions: if you have any underlying medical conditions such as liver or kidney disease, malabsorption syndrome, or a history of eating disorders, you should address these with your doctor.

  • Pregnancy/breastfeeding: Orlistat is not recommended for anyone pregnant or breastfeeding.

Medications: discuss what medications you are currently taking with your doctor as Orlistat can interact with certain medications such as cyclosporine, warfarin, and some antiretroviral medications.

How to take Orlistat

Orlistat, in the form of Xenical, is a capsule that is swallowed with water before, during, or up to an hour after each of your three main daily meals.

Is Orlistat right for you?

If you’re considering using orlistat for weight management, here are some questions to ask yourself:

  • Are you overweight or obese? Orlistat can only be prescribed to those with a BMI of 30+, or 27+ if there is a risk of developing weight-related diseases, such as heart disease or high blood pressure. 

  • Are you committed to a healthy lifestyle? Orlistat is most effective in tandem with a calorie-controlled diet and exercise program. 

  • Have you discussed it with a healthcare professional? It’s important to get the opinion of your doctor whether orlistat is the right path for you. 

If you haven’t discussed prescription weight loss treatments with your doctor, you could seek independent advice from a qualified GP through our Online Doctor service; it’s an easy-to-follow consultation that will assist you with understanding your options, and it will result in a professional recommendation that you can trust.

Orlistat FAQs

What happens if you take Orlistat without eating?

Orlistat works by blocking the absorption of some of the fat from your meals, so if your meals contain no or very little fat, it won’t have any effect. If you’re skipping a meal or having a meal that contains no fat, you shouldn’t take orlistat.

Should I take Orlistat or Xenical?

Orlistat and Xenical are the same type of medicated weight loss treatment, orlistat is a generic medicine and is the active ingredient found in ‘Xenical’, which is a branded treatment.

How to get the best results from Orlistat?

Orlistat isn’t a magic cure for weight loss but is a catalyst to help make meaningful changes in your life. To get the best results from orlistat you must adopt long-term healthy lifestyle changes including physical exercise and a calorie-controlled diet.

Orlistat vs Ozempic: which should I take?

Orlistat and Ozempic have different use cases with Orlistat being used to help treat weight loss and the prevention of weight-related diseases and Ozempic is used for the treatment of type 2 diabetes. Ozempic is not licensed for weight management in the UK.

Orlistat vs Saxenda: which should I take?

Whilst both Orlistat and Saxenda are used for weight management, they work in different ways. Orlistat reduces dietary fat absorption within the body and Saxenda reduces your appetite through hormones. Not sure which is right for you? Use our Online Doctor service to get independent advice from a qualified GP.