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Adeel Arshad

Authored on 24 January 2024 by Adeel Arshad,

Reviewed 24 January 2024 by Dr Ruch Karunadasa.

Xenical / Orlistat

(Generic Xenical)

Part of our weight loss treatment plan
Oral medication

Orlistat/Xenical is a prescription-only weight-loss medication. The usual dose is one 120mg capsule taken with each of your three main meals per day. It works by reducing the absorption of fat from your diet.

 Nutrition information for medication

Orlistat/Xenical is approved to help you lose weight in conjunction with an active lifestyle and a calorie-controlled balanced diet.

Approved to help lose weight

Orlistat/Xenical should be taken alongside a calorie-controlled diet and exercise to help you lose weight. Exercise and balanced diet will help you maintain a healthy weight even when you stop taking your medication.

What is Xenical / Generic Orlistat?

Xenical/Orlistat should be taken alongside a calorie-controlled diet and exercise to help you lose weight. Exercise and balanced diet will help you maintain a healthy weight even when you stop taking your medication.

How does Orlistat/Xenical work?

Xenical contains the active ingredient Orlistat. This is available as the branded Xenical or generically as Orlistat; both medicines contain 120mg of Orlistat. Xenical/Orlistat is a prescription-only medication that works in your stomach by preventing digestion of about a third of the fat you eat in each meal. It does this by attaching itself to the enzymes that usually breakdown fat. Any undigested fat is passed through your system when you go to the toilet. It does not affect the hormonal balance of your brain or affect the way you think about food.

In many clinical trials, when taken in combination with diet and exercise, Orlistat has been proven to be an effective weight-loss medication. Patients taking Orlistat reported a significantly greater weight loss than diet and exercise alone.1

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Is Xenical/Orlistat suitable for me?

If you are overweight Xenical/Orlistat can aid weight loss when used alongside a calorie-controlled diet and exercise. It is particularly effective if you have previously found it difficult to lose weight with diet and exercise alone. When combined with a healthy diet and exercise you could lose around 1kg (2lb) more for every 2kg (4lb) you lose from dieting alone.

How do I take Xenical/Orlistat?

The usual dose is one 120 mg capsule taken with each of your three main meals per day. You can take it immediately before, during or up to one hour after a meal.

To ensure your results are effective and long-lasting, you should combine Xenical/Orlistat with exercise and the right diet. You need to have a balanced, calorie-controlled diet that is rich in fruits and vegetables and contains no more than 30% fat. Carbohydrate, protein and fat should be evenly distributed across your three daily meals, and to benefit most, you should try to avoid any fat-containing snacks like biscuits, chocolates or crisps in between meals.

If you miss a meal or have a meal that has zero fat in it, you do not need to take your dose of Xenical/Orlistat as it only works in the presence of fat in your diet.

If you miss a dose you can take it within an hour of your meal but do not take a double dose.

Tell us if, for any reason, you have not taken your medicine exactly as prescribed.

Otherwise, we may think that it was not effective or well tolerated and may change your treatment unnecessarily. We will discontinue the treatment with Xenical/Orlistat after 12 weeks if you have not lost at least 5 % of your body weight as measured at the start of treatment. .

You must take a daily multivitamin supplement alongside Xenical/Orlistat. Some of the vitamins and minerals that your body needs to function are fat-soluble, so if you do not digest all the fat in your diet you may become deficient.

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What information do you need to know about me?

Our advice is to read the information on obesity and when you feel ready, complete a confidential consultation with one of our team of doctors. Do your best to give as much detail as possible to ensure that our team has all the information, they need to assess your condition.

We will only prescribe Xenical/Orlistat when it is safe to do so and in your best interests.

Xenical/Orlistat is not suitable for children, women that are pregnant, or breastfeeding. Xenical/Orlistat is also not suitable for patients with food absorption difficulties or reduced bile flow.

You must tell us about all the medications that you use, including prescribed, over the counter and supplements, because there may be some interactions between these medicines and Xenical/Orlistat.

What are the possible side effects of taking Xenical/Orlistat?

As with all medicines, Xenical/Orlistat can cause some side effects, although not everyone will experience these. You may notice changes to your bowel movements due to increased levels of fat passing through your digestive system. These changes are quite normal, often mild and usually occur in the first few weeks of starting Xenical/Orlistat. Typical symptoms can include increased flatulence (wind), an increase in the number of bowel movements with the potential for an oily discharge. If you eat meals that contain a higher level of fat than the recommended 30%, you may experience problems in controlling bowel movements. Over time these symptoms may reduce or disappear, especially if you keep to the recommended diet advice.

Always tell a doctor or pharmacist as soon as possible if you do not feel well while you are taking Xenical/Orlistat.

Very common side effects (affects more than 1 user in 10)

  • Headache
  • Abdominal pain or discomfort
  • Urgent or increased need to open the bowels
  • Flatulence (wind) with discharge
  • Oily discharge, oily or fatty stools
  • Liquid stools
  • Low blood sugar levels (experienced by some people with type 2 diabetes)
  • Upper respiratory infections
  • Flu (influenza)

Common side effects (affects 1 to 10 users in 100)

  • Rectal pain or discomfort
  • Soft stools
  • Incontinence (stools)
  • Bloating (experienced by some people with type 2 diabetes)
  • Tooth or gum disorders
  • Irregularity of menstrual cycle
  • Tiredness
  • Anxiety
  • Lower respiratory infections
  • Urinary tract infections

The following side effects have also been reported but their frequency cannot be estimated from the available data:

  • Allergic reactions. The main symptoms are itching, rash, wheals (slightly elevated, itchy skin patches that are paler or redder than surrounding skin), severe difficulty in breathing, nausea, vomiting and feeling unwell
  • Skin blistering (including blisters that burst)
  • Diverticulitis
  • Bleeding from the back passage (rectum)
  • Increases in the levels of some liver enzymes may be found in blood tests
  • Hepatitis (inflammation of the liver). Symptoms can include yellowing skin and eyes, itching, dark coloured urine, stomach pain and liver tenderness (indicated by pain under the front of the rib cage on your right-hand side), sometimes with loss of appetite. Stop Xenical/Orlistat if such symptoms occur and tell your doctor
  • Gallstones
  • Pancreatitis (inflammation of the pancreas)
  • Oxalate nephropathy (build-up of calcium oxalate which may lead to kidney stones)

Xenical/Orlistat can also affect other medications that you are taking such as anticoagulants. Always tell the doctor about all your medicines and read the patient information leaflet fully before you start taking Xenical/Orlistat.

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  1. A systematic review of the clinical effectiveness and cost effectiveness of Orlistat in the management of obesity –
  4. Side effect list compiled from data taken from – Please visit their website for a complete and comprehensive list. is a stand-alone entity and is in no way associated with this site.

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