• Orlistat


Medication features

Orlistat is a weight loss pill that helps your body reduce the amount of fat it absorbs. By passing more fat through your bowels, you are able to have more success in losing weight when adopting a plan to lose weight.

  • Reduces the amount of fat the body absorbs
  • Take THREE times daily with meals
  • Average of ~5% body weight loss


Buy Orlistat Online in the UK

You can buy Orlistat 120mg capsules online from our UK registered online pharmacy. Once you have completed the online doctor consultation, our UK trained and registered GPs will review your assessment and prescribe the selected medication if appropriate. The prescription is then passed to our UK registered pharmacy team, who will dispense and dispatch your prescription to your door. 

Orlistat Summary

What is it?Used as a weight loss aid
How It WorksPrevents the absorption of some of the fat from foods eaten, which is then eliminated in bowel movements.
Effectivness?Helps patients lose an average of ~5% of their body weight
Brand NamesXenical (prescription), Alli (over-the-counter)
Common Side EffectsGastrointestinal symptoms (e.g., oily spotting, flatulence with discharge, urgent bowel movements, fatty/oily stool).
PriceFrom £17.50

What is Orlistat?

Orlistat is a weight loss medication used to assist people who are overweight in reducing their BMI. It is indicated in people with a BMI over 30, or 28 for those with additional risk factors. Orlistat is the generic version of the better-known brand, Xenical. They come in capsule form, and the prescription-only version contains 120mg of the active ingredient.

How Does it Work?

Orlistat capsules work by preventing around a third of the fat from the food you eat from being digested. The undigested fat is not absorbed and is passed out with your faeces. Orlistat works in the same way as the over the counter medicine Alli. They contain the same active ingredient (Orlistat), however, the prescription version is twice the strength (120mg instead of 60mg). 

Because Xenical is no longer the only manufacturer of Orlistat, this has helped lower the price of the generic form of the drug. By decreasing the amount of fat the body absorbs and improving your diet and exercise routine, it is possible to achieve significant weight loss.

Before using Orlistat or Xenical, you should read the patient information leaflet.

Orlistat Dosage

The usual dosage of Orlistat is 120mg three times a day (each time you eat a  meal). As it works to reduce the fat absorbed by your body, you do not need to take a dose if you skip a meal. You also don't need to take a dose if you have a 0 fat meal, as there will be not fat for the body to absorb!

You can read about what happens if you take Orlistat without a meal in our guide.

Losing weight with Orlistat

Orlistat helps you avoid gaining weight by reducing the amount of fat absorbed by your body. However, it does not necessarily cause you to lose weight. Therefore, it’s still important to stick to a healthy diet and exercise plan. In combination, the drug can be successful in reducing your weight into a more healthy BMI range. 

Orlistat (Xenical) is usually recommended if you have made a significant effort to lose weight through diet, exercise or changing your lifestyle.

Even then, orlistat is only prescribed if you have:

  • a body mass index (BMI) of 28 or more and other conditions related to weight, such as high blood pressure
  • a BMI of 30 or more

How To Get The Best Results From Orlistat


So does Orlistat actually work? In short, yes! Orlistat is recommended to be taken over a 12 week period and most people can expect to lose around 5% of their original body weight if combined with a good lifestyle and regular exercise.

The medication itself should reduce the amount of dietary fat absorbed by your body by around 33%, so this gives you a good opportunity to lose weight if you increase the amount of exercise you do.

Studies have shown you are around 3 times more likley to lose significant weight with Orlistat, than patient who take a dummy pill.

Read more about how to get the best results from Orlisat in our helpful guide.

Orlistat Results

In the graphic below you can see the difference in weight loss with Orlistat or placebo during a 1 year scientific study. You can find out more about experiences with the treatment, from our UK patient Orlistat reviews.

Orlistat Results

Changes in waist size

The table below shows the difference in waist circumference when taking Orlistat or placebo.

TreatmentChange in waist circumference after 1 year
Orlistat5.27% reduction 


 2.54% reduction


Side Effects of Orlistat

Common side effects of Orlistat (Xenical) can include:

  • fatty or oily stools
  • more regular bowel movements
  • needing the toilet urgently
  • oily discharge from your rectum (you may have oily spots on your underwear)
  • flatulence (wind)
  • stomach and abdominal pain
  • headaches

These side effects are much less likely to occur if you stick to a low-fat diet.

Women taking the oral contraceptive pill are advised to use an additional method of contraception, such as a condom if they experience severe diarrhoea while taking orlistat. This is because the contraceptive pill may not be absorbed by your body if you have diarrhoea, so it may not be effective.

If you have any side effects you are concerned about, speak to your doctor or pharmacist.


While Orlistat provides the most affordable treatment, some patients do prefer to stick to the original branded version of the drug, Xenical. This also contains 120mg of Orlistat but is more expensive.

Diet and exercise alone, is always the preferred method for weight loss. This is not always possible, however. Many patients may have chronic pain which can make exercise difficult.

Medication such as Saxenda Pens, work to suppress appetite and have shown good results. A new and improved weight loss injection, Wegovy, has recently been approved in the UK and was released in September 2023. Read about how Wegovy compares to Orlistat in our guide.

Ozempic and Mounjaro are also medications which are availablein the UK for weight loss. These are both injection pens, and can help achieve ~15-20% body weight loss.

You can also find information online for diet advice, such as the British Heart Foundation weight loss advice.

Orlistat Prices

Orlistat 120mg - 42 capsules£17.50
Orlistat 120mg - 84 capsules£35.00
Orlistat 120mg - 168 capsules£68.95
Orlistat 120mg - 252 capsules£99.95


How Does Orlistat Work for Weight Loss?

Orlistat works by binding to the enzymes in the body to prevent the absorption of fat. On average, Orlistat will work on around a quarter to one-third of the fat you eat. Instead of this fat being absorbed, it passes through your gut. For people with high-fat diets, this can result in oily stools.

Who can use Orlistat?

Orlistat is indicated in people with a BMI over 30, or in people who have a BMI over 28, with another weight-related condition, such as diabetes or high blood pressure.

What is the difference between Orlistat and Xenical?

Xenical is the branded version of the drug, Orlistat. Orlistat is the generic form of Xenical. Medically, they are exactly the same drug and contain exactly the same strength (120mg of Orlistat).

What is the difference between Orlistat / Xenical and Alli?

Alli is an over the counter version of Orlistat, which is half the strength of the prescribed version. Alli contains 60mg of Orlistat, compared to 120mg in Xenical and generic prescription Orlistat.

Further Reading

Wegvoy vs Orlistat

How to get the best results on Orlistat

 10 tips for losing weightWorld Obesity Day 2022 


Written by Qualified Experts

All of our medication and condition content is writted by UK qualified pharmacists and doctors.


Karim Nassar, Pharmacist

Authored By: Karim Nassar

GPhC Registration: 2071234

Date Authored: 12/03/2019


Hywel McGlinchy, Clinical Pharmacist

Reviewed By: Karim Nassar

GPhC Registration: 2064752

Last reviewed on: 12/03/2024



Info Leaflet

Before taking any medication, it is important to read the Patient Information Leaflet. You can find information leaflets for your medicines by typing them into the search bar at medicines.org, or by contacting us.


Orlistat should not be taken if you are;

Pregnant or breastfeeding
Have a BMI less than 28
Are under 18

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