The study, published in the British Journal of Clinical Pharmacology, focuses on prescriptions in the UK, where the drugs are not licensed for use under the age of 18. Extrapolated across the whole population, the results indicate that around 1,300 young people are now being prescribed off-licence anti-obesity drugs each year.

More than three quarters of those included in the study received prescriptions for orlistat, also known as Xenical or Alli. Orlistat has been approved for children as young as 12 in the US, but only for adults in the UK. Most patients given orlistat stopped using it very quickly, on average after just three months, and therefore would have been unlikely to see any benefit.

"It's possible that the drugs are being given inappropriately, or that they have excessive side effects that make young people discontinue their use. On the other hand they could be expecting the drugs to deliver a miracle "quick fix" and stop using them when sudden, rapid weight loss does not occur," said Russell Viner, one of the authors of the study based at the General & Adolescent Paediatrics Unit at University College London.

As anti-obesity medications are expensive, not sticking to drug programmes wastes valuable resources. Study author Ian Wong says that children who are prescribed orlistat may need more support and should be made fully aware of the potential side effects, which include loose, oily stools if fat intake is not reduced.

"You have to tell them that, yes, it is healthier not to absorb the fat, but if they continue to eat as much as they used to then it will be really unpleasant. The key thing is that the drug itself is not the answer. Kids should only be using it as part of a comprehensive weight-loss programme," said Wong.

The researchers used data from the General Practice Research Database, which covers around 5% of the UK population. 452 children and adolescents were prescribed anti-obesity drugs between 1999 and 2006. Over eight years, the number of young people receiving prescriptions rose 15-fold from 0.006 per 1,000 to 0.091 per 1,000.

According to the researchers, it is highly unlikely that the drugs are doing any damage, as well-conducted short-term clinical trials did not report life-threatening side-effects in young people. But they say further research into the safety and efficacy of anti-obesity drugs in children and adolescents in clinical practice is warranted, particularly considering the dramatic increase in prescriptions and likely further increases due to childhood obesity globally.

Note: If no author is given, the source is cited instead.

• Diet and Weight Loss
• Obesity

• Dieting and Weight Control
• Child Psychology

• Public Health
• Religion

• Anti-obesity drug
• COX-2 inhibitor
• Dorian Gray syndrome
• Appetite
• Psychopharmacology
• Body mass index