The UK’s Medicines and Healthcare products Regulatory Agency has issued a renewed warning over the dangers of buying drugs from unregulated sources on the Internet after the discovery of fake slimming pills.

Counterfeit forms of GlaxoSmithKline’s Alli (orlistat) have thus far only been found by regulators in the US but could easily make their way into the UK supply stream via unlicensed online pharmacies, the MHRA has warned, posing a real danger to patient safety.

Counterfeit drugs are inherently associated with a higher risk of harm, and laboratory tests have revealed that this batch of fake Alli contains a high amount of sibutramine, the active ingredient in another weight loss drug Reductil, European sales of which have just been suspended because of fears over an increased risk of cardiovascular side effects such as heart attack and stroke.

“Buying weight loss medication from unregulated websites is a dangerous way to slim down,” said MHRA Head of Enforcement Mick Deats. “You don’t know what you’re taking and your condition is not being monitored by a healthcare professional. It’s just not worth taking that type of risk,” he stressed.

Patients taking Alli, which is available over-the-counter in the UK, have been advised that counterfeit versions of the drug can be distinguished by: the absence of a ‘Lot’ code on the end flap of the outer packaging; the absence of the words ‘sealed for your protection’ on the inner safety seal under the plastic cap; and capsules containing white powder instead of small white pellets.

Furthermore, in the UK the licensed drug is not available in packs of 120, only in smaller packs of 42 and 84, and every capsule is clearly marked as Alli in the UK and Orlistat in the US, while counterfeits carry no such marking, the MHRA said, and further stressed that bona fide online pharmacies will always have a physical address clearly displayed and as well as the Royal Pharmaceutical Society of Great Britain’s green cross logo.