Slimming tablets and a tape measure

Xenical (Orlistat)

What is it?

Xenical is a prescription-only medication designed to help obese patients lose weight. It blocks the bodies' ability to absorb fat, so helps those trying to slim.

It is made by the healthcare manufacturers, Roche. It was approved for use in America in 1999 and in Europe in 1998. A lower dose version of Orlistat is marketed under the name of Alli and sold by GlaxoSmithKline over the counter at pharmacies in the U.S.A. and Europe without a prescription.

How does it work?

Xenical stops the body taking in up to 30% of the fat a patient consumes. It is a synthetic derivation of lipostatin, which is a naturally occurring lipase (fat) blocking enzyme found in the gastrointestinal tract (the small intestine).

Fat molecules are normally too large to be absorbed from the gut directly into the bloodstream. There are two lipases, called pancreatic and gastric, which break down the fats from our diet so they are small enough to pass into the blood. Xenical blocks these enzymes from working, so some of the fat passing through the gastrointestinal tract cannot being absorbed, which means that the calories are not taken in by the body.

As the fat is not broken down, it passes out of the body in the faeces. The calorie intake is therefore reduced, while still allowing the body to get the fat and calories it needs.

How do I get Xenical?

If you live in Europe, you will need to be prescribed the medication by a doctor. It is available on the NHS and other European health services.

It is also available privately, after consultation with a doctor. Some clinics offer this service online. Do not take Xenical without seeking advice from a doctor first.

In the U.S and Europe you can buy low dose Orlistat from your pharmacist, who, after an assessment, will advise you on whether it is suitable for you.

Are there any side effects?

Unfortunately, Xenical can have some unpleasant side effects, especially if the patient does not follow the recommended diet. The patients' diet should only derive 30% of calories from fat in any given meal. The diet should also have a high content of fruit and vegetables. The fat content should be spread throughout three meals., meaning that you cannot have one meal high in fat and two low in fat to compensate.

The most frequent side effects have been patients experiencing problems with their bowel movements, including passing oily discharge, oily stools, increased or uncontrolled bowel movements and flatulence. Some have also had abdominal discomfort. These have been the most common reasons for people discontinuing with the medication.

Other side effects have been inflammation of the liver, fatigue, urinary tract infection, tooth or gum problems and gall stones.

This is not a complete list of side effects, which can be found in the patient information leaflet you will receive when prescribed Xenical.

Who is it suitable for?

It is not right for you if:

Please note this is not a complete list of contraindications, which is why you must be cleared by your doctor or pharmacist to take Xenical.

Anything else I should know?

Some patients experience diarrhoea while taking this medication, which can interfere with the contraceptive pill. Be very careful if you are taking contraceptives.

It is recommended that you supplement your diet with multi-vitamins containing fat-soluble nutrients, as Xenical can interfere with how your body absorbs vitamins like beta-keratin. You should take one vitamin pill two hours before or after taking Xenical, perhaps at bedtime.

You should not take Xenical for more than 2 years. If after three months you have lost less than 5% of your initial body weight, then you should not continue taking it.

And finally...

If you are considering buying Xenical, especially over the internet, be careful where you get it from. There is a big trade in fake pharmaceuticals, particularly in weight loss and impotence medications. We recommend The Online Clinic for Xenical online as they use UK based doctors, dispense from a registered pharmacy and include guaranteed next day delivery as standard.

Even if you don't take our recommendation, please make sure the clinic you go to uses doctors registered by the relevant authorities for that country. Check the pharmacy you buy from or are referred to is also registered with the appropriate statutory body.

Be wary of websites offering very cheap or 'discount' drugs. As they are likely to be selling counterfeit medication.

Further info


Reductil (Sibutramine) is a weight loss drug that affects your appetite. Get more info

Other treatments

There are hundreds and hundreds of other weight loss treatments on the market, from pills to drinks to creams. Get more info