How does it work?

Xenical capsules contain the active ingredient orlistat, which is a type of medicine called a lipase inhibitor. It is used to aid weight loss in people who are overweight or obese.

Orlistat is not absorbed into the bloodstream, but works locally in the stomach and small intestine, where it prevents the action of two compounds found in the digestive juices. These compounds (known as enzymes) are called gastric and pancreatic lipases. They normally break down fats that we consume in our diet.

The fats we consume in our diets are made of molecules that are too large to be absorbed from the gut into the bloodstream. They need to be broken down into smaller molecules during the process of digestion, in order to be absorbed into the bloodstream. Gastric and pancreatic lipases are the compounds in the gut that carry out this function.

Orlistat works by preventing gastric and pancreatic lipases from working. One Xenical capsule is taken three times a day at mealtimes to prevent fat that is eaten in the meals from being broken down and absorbed by the body. This means the body cannot use the fat as a source of energy, or convert it into fat tissue. Instead, the fat is excreted in the faeces. This helps weight loss.

Xenical should be used in conjunction with increased physical activity and a reduced calorie, lower fat diet. Approximately 30 per cent of your daily calories should come from fat, and your daily intake of fat, carbohydrate and protein should be spread evenly over your three main meals. For example, for a diet of 1400 calories per day, each meal should contain approximately 15 grams of fat. The actual calorie intake and fat consumption that you should follow will depend on your initial weight and level of physical activity - there is guidance provided in the package leaflet, and your doctor or pharmacist can also advise.
What is it used for?

* Aiding weight loss in people who are obese or overweight.

Xenical is prescribed to aid weight loss in obese people who have a body mass index (BMI) of 30kg/m² or more. It can also be prescribed to overweight people who have a BMI of 28kg/m² or more, if they also have additional risk factors for obesity-related diseases.
Warning!

* This medicine should be taken immediately before, during, or up to one hour after each main meal. If a meal is missed, or contains no fat, you should leave out the dose. This is because the medicine will have no effect if no fat has been consumed.
* Do not take more than three capsules per day.
* As this medicine works by preventing the absorption of fat, you are more likely to experience digestive side effects such as wind, oily spotting from the rectum, sudden bowel motions, and soft, fatty or oily stools, if you take the medicine with a meal that is very high in fat.
* This medicine may potentially impair the absorption of fat-soluble vitamins (A,D,E,K) from the gut. To ensure you receive adequate nutrition, your diet should be rich in fruit and vegetables. Your doctor may also recommend a multivitamin supplement. If you do take a multivitamin supplement, it should be taken at least 2 hours after your orlistat dose, or at bedtime.
* If you experience severe or persistant rectal bleeding while taking this medicine you should consult your doctor so that this can be investigated.
* This medicine can cause diarrhoea, which if severe, can reduce the effectiveness of oral contraceptive pills. Women taking the pill for contraception should therefore use an additional method of contraception, eg condoms, to prevent pregnancy, if they experience severe diarrhoea while taking this medicine. Follow the instructions in the leaflet provided with your pill.
* Your doctor may ask you to stop treatment if you have been unable to lose at least five per cent of your body weight after 12 weeks of treatment with this medicine.
* Once you stop taking this medicine it is important to continue to follow a healthy, balanced diet and take regular exercise to make sure the weight you have lost stays off.

Use with caution in

* Long-term kidney disease.
* Diabetes. (If you have diabetes, weight loss may be accompanied by an improvement in your blood sugar levels, in which case your dose of antidiabetic medicine may then need to be adjusted. Ask your doctor or pharmacist for advice.)
* Underactive thyroid gland (hypothyroidism). (Xenical may affect the absorption of levothyroxine - see end of this factsheet for more information.)
* Epilepsy. (Xenical may affect the absorption of antieplipetic medicines - see end of this factsheet for more information.)

Not to be used in

* People who suffer from a long-term condition in which the gut does not absorb sufficient nutrients (chronic malabsorption syndrome).
* People in whom the normal flow of bile from the liver to the intestines is blocked (cholestasis).
* Breastfeeding.
* This medicine is not licensed for use in children under 18 years of age. However, it may sometimes be prescribed by specialists for children over 12 years of age who are obese. This is an unlicensed use of the medicine.

This medicine should not be used if you are allergic to one or any of its ingredients. Please inform your doctor or pharmacist if you have previously experienced such an allergy.If you feel you have experienced an allergic reaction, stop using this medicine and inform your doctor or pharmacist immediately.
Pregnancy and breastfeeding

Certain medicines should not be used during pregnancy or breastfeeding. However, other medicines may be safely used in pregnancy or breastfeeding providing the benefits to the mother outweigh the risks to the unborn baby. Always inform your doctor if you are pregnant or planning a pregnancy, before using any medicine.

* The safety of this medicine in pregnancy has not been established. It is not recommended for use during pregnancy. It should only be used if the benefits to the mother outweigh any possible risks to the developing baby. Seek medical advice from your doctor.
* It is not known if this medicine passes into breast milk. It should not be taken by mothers who are breastfeeding. Seek medical advice from your doctor.

Side effects

Medicines and their possible side effects can affect individual people in different ways. The following are some of the side effects that are known to be associated with this medicine. Just because a side effect is stated here does not mean that all people using this medicine will experience that or any side effect.

You are less likely to experience digestive side effects if you follow the instructions on what to eat while taking this medicine and do not take it with meals that are high in fat.