In short

  • Orlistat is a weight loss medication taken by people who are overweight or obese.
  • Orlistat blocks the digestion of nearly ⅓ of the fat you consume, which in turn reduces the number of calories absorbed by your body.
  • The recommended dose of orlistat is one 120mg capsule, taken three times daily alongside a fat-containing meal.

Last Updated: 25/06/2025

Orlistat is a weight loss medication taken by people who are overweight or obese. Orlistat works by blocking the action of certain enzymes in your intestines. These enzymes, called lipases, are responsible for breaking down fat into digestible forms.

Orlistat blocks the digestion of nearly ⅓ of the fat you consume, which in turn reduces the number of calories absorbed by your body. The undigested fat that is not absorbed by your body is removed via your faeces.

How is Orlistat Used?

The recommended dose of orlistat is one 120mg capsule, taken three times daily alongside a fat-containing meal. If the meal does not contain fat, or you have missed a meal, you do not need to take the medication.

For orlistat to have an effect on your weight, it cannot be taken alone. Orlistat needs to be used alongside weight loss measures, such as a calorie-controlled diet and exercise.

This medication is recommended for 3 months of use but can be extended for a long time if you have noticed your body weight has decreased by 5% during this time period. At this 120mg dose, three times a day, orlistat has been shown to reduce body fat by 30%.

Side Effects of Orlistat

Like all medications, there is a chance of experiencing side effects when using orlistat.

These side effects may include (but are not limited to);

  • Frequent bowel movements and increased bowel urgency
  • Oily, loose stools and oily discharge
  • Flatulence with discharge

It is advised not to take an Orlistat capsule when eating a meal with a high amount of fat (more than 15g), as this can cause your side effects to be worse.

When Does Orlistat Start Working?

Orlistat works immediately once you start taking the medication. By taking Orlistat as outlined with a balanced diet (low-fat diet and calorie intake) and regular exercise, you should start to lose weight within 2 weeks.

The bulk of the weight loss is seen during the first 6 months of using Orlistat. It is advised to keep exercising and consuming a low-calorie diet when you stop taking the medication as you might then notice some weight gain again.

How Much Weight Can You Lose on Orlistat?

A clinical trial looking at 743 obese patients on Orlistat found that they had lost 10.3kg on average over a 1 year period compared to only 6.1kg of patients not taking the medication.

Another study following 80 obese patients taking Orlistat, found that the average weight loss achieved was 4.65kg vs 2.5kg in patients taking a placebo over a 6-month period.

Orlistat Effectiveness

These results will be affected by your dietary fat intake; if you are already on a low-fat diet, you may not see as big a difference.

Are there Alternatives to Orlistat?

For patients who find that they experience severe side effects when using orlistat, Alli may be useful. Alli contains the same active ingredient as orlistat, but uses a lower dose – 60mg rather than 120mg. While you may still experience side effects at this dose, they should be less severe. However, this also means the weight loss effects may not be as pronounced as well.

Alli is available over the counter, and can be purchased without a prescription.

For those who want a different approach to weight loss, there are injections such as Saxenda and Wegovy. Rather than binding fat, the active ingredients in these medications act directly on your endocrine system – the hormones which control many different aspects of your body. By acting on the same receptors as other hormones, these treatments can reduce your appetite, making you feel fuller for longer and slowing digestion.

With the launch of Wegovy, Saxenda will be phased out of production, meaning that Wegovy will be the primary weight management injection on the market.

How to Get Orlistat?

Orlistat is only available on prescription due to the effects and potential for abuse. As Simple Online Pharmacy puts patient wellbeing front and centre, we will ask a few quick questions to ensure this treatment is right for you.

Once you have completed this assessment, your answer will be reviewed by our team of UK-trained pharmacists. If they have no concerns, they will prescribe Orlistat for you, and our pharmacy team can arrange delivery straight to your doorstep.

Sources

References

2 sources were selected to match the subject of this article. Link destinations were checked twice when added. This does not mean every statement has been individually source-mapped or clinically approved.

  1. Xenical 120 mg hard capsules: Summary of Product Characteristics

    Neon Healthcare via electronic medicines compendium · HTML · regulator-approved product information · Current emc SmPC · Link destination checked 5 September 2026

  2. Orlistat: a medicine to treat obesity

    NHS · HTML · medicine patient guidance · NHS Medicines A to Z · Link destination checked 5 September 2026

Reference links open the cited source pages. If you spot something out of date, tell our content team.

Who wrote this

Written and reviewed by our team

Authored by

Safiyyah Ramzan

Content Writer

Safiyyah started working with Simple Online Pharmacy in 2023 and is currently working toward a degree in medicine. She aims to write clinically-sound content for all.

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Medically reviewed by

Karim Nassar, Co-Founder, Pharmacist & Author

Karim Nassar

Co-Founder, Pharmacist & Author

Karim is a registered pharmacist with the General Pharmaceutical Council (GPhC) and was a founding member of Simple Online Healthcare in 2015. With a Master of Pharmacy degree from Strathclyde University, Karim brings a strong foundation in pharmaceutical care and a passion for leveraging digital solutions to improve patient access to healthcare.

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Sources cited

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