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Xenical: weight-loss wonder drug?

We take a look at the concerns raised about the marketing of weight-loss drug orlistat (contained in the medicine Xenical).

xenical package
Last updated: 25 May 2016


Checked for accuracy by our qualified fact-checkers and verifiers. Find out more about fact-checking at CHOICE.

Orlistat, sold in Australia as Xenical, is a drug that's promoted as a treatment for those who are overweight and obese. It works in your stomach and intestine by preventing your body from absorbing as much as 30% of the fat you eat, and as a result it can help you lose weight. 

But Xenical isn't the magic-bullet solution to obesity, and we have concerns about its over-the-counter availability at pharmacies.

How does Xenical work?

Xenical helps you lose weight when used in conjunction with a reduced-fat diet and exercise program. Xenical is taken when you're eating fatty food, so you'll usually take a capsule with each of the three main meals a day (unless you know the meal you're eating contains no fat). You must limit the fat that you eat in a day to less than 12g in each meal, and no more than 40g per day. A really fatty meal can result in some unpleasant side effects.

A clinical trial has found that participants who took Xenical three times a day lost an average of 4.8kg in the first month, increasing up to 7.2kg at 3 months. After a year, the average loss was 10% of original body weight. A longer term study over four years showed a weight loss of 5.8kg in the Xenical group versus 3kg in a placebo group, with about one in four patients losing 10% or more body weight.

Possible risks and side effects of Xenical

Because you don't absorb all the fat you eat when taking Xenical, the most common side effects are gastro-intestinal problems, including:

  • oily bowel movements
  • frequent bowel motions and flatulence
  • diarrhoea
  • abdominal pain.

Xenical also affects the amount of fat-soluble vitamins and beta-carotene you absorb, so a vitamin supplement taken at least two hours before or after a dose of Xenical may be needed.

Who can use Xenical?

You're only eligible to take Xenical if you have:

  • a BMI (body mass index) of 30 and over; or
  • a BMI of 27 and over with other risk factors like diabetes or high blood pressure.

Xenical isn't currently recommended for children or teenagers under 18 years or adults over 74 years of age.

How much does Xenical cost?

Xenical costs approximately $120 for one month's supply.

How do you get it?

Xenical is available from pharmacies. You don't need a prescription, but before it can be sold pharmacists are supposed to assess you for suitability. They're expected to check:

  • weight, height and BMI
  • health status (existence of conditions such as diabetes, high blood pressure, osteoporosis, for example)
  • age
  • factors contributing to excess weight (including genetic influences, life states and events, and medical conditions or treatments).

If Xenical is dispensed, pharmacists should then give counselling on points including dosage, side effects and lifestyle modifications required (including diet and exercise).

However, we recommend seeing your doctor before getting Xenical. It's always sensible to be fully checked out before trying any new medication – your GP is the best person to advise you on your situation and help you decide on the best and safest way to tackle your problem.

What's the problem with Xenical being available without a prescription?

Originally when it went on sale in Australia, Xenical was a schedule 4 (S4, "prescription only") drug. But in October 2003 it was granted schedule 3 (S3, "pharmacist only") status, which meant it no longer requires a prescription.

Xenical has an important place in helping people who are obese or who are overweight with obesity-related health problems. But we're concerned that its S3 status means that Xenical is too easily accessed by people who shouldn't be taking it.

CHOICE shadow shop

In theory, there are guidelines for pharmacists to follow when supplying Xenical. These include an assessment that should consider BMI and waist circumference, health status and age, and counselling on points including dosage, drug interactions, side effects and advised lifestyle modifications (including diet and exercise).

We sent a shadow shopper to 30 different pharmacies in the Sydney metropolitan area over four days in December 2006, and asked her to buy Xenical in each one.

About our shadow shopper

Age: A young-looking 19-year-old girl

Height: 168cm

Weight: 70kg

BMI: 24.8

Diet: Healthy diet of meat, fruit and vegetables, rarely eats takeaway food.

Exercise: Walks three to four hours a week, and swims regularly.

Occupation: Full-time student, employed part-time as a lifeguard at a swimming centre.

Health: No obesity co-morbidities (such as diabetes, high blood pressure).

Xenical suitability: Xenical isn't appropriate for her, according to Pharmaceutical Society of Australia (PSA) guidelines.

What we found

Our shadow shopper was sold Xenical in 24 (80%) of the 30 pharmacies visited. This clearly demonstrated that many pharmacists weren't following PSA guidelines and were supplying the drug inappropriately. Here are the details:

  • Less than one third of the pharmacies measured or asked for her height and weight. These details are needed to calculate BMI, which should be considered before supplying Xenical.
  • Her BMI was calculated in just nine pharmacies (in one of these she had to do the calculation herself). Three of these pharmacies went on to sell her Xenical.
  • Two correctly calculated her BMI as 25, but sold Xenical to her anyway. The third incorrectly calculated her BMI as 27 (using her height and weight measurements, which she gave them) and sold her the drug.
  • No-one measured or asked for her waist circumference.
  • No-one confirmed our shopper's age (even though the safety and effectiveness of Xenical in children hasn't been established, so it's not recommended to children or adolescents under 18 years of age).
  • On several occasions the pharmacy commented to our shadow shopper that she didn't need Xenical, but sold it to her regardless.

In the 24 pharmacies where she was sold Xenical:

  • Eight gave no directions on how to use the product, and of the 16 who did, the explanations were brief.
  • Only 13 gave her some counselling or advice about diet and exercise when taking the drug.
  • Side-effects of Xenical were mentioned in just 16 pharmacies.
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