The MHRA has warned patients against buying medicines from unregulated websites after counterfeit Alli, containing unlicensed ingredient sibutramine rather than orlistat, was discovered in the US.

The counterfeit Alli could be distinguished from the genuine product because the capsules were unmarked and contained white powder rather than small white pellets, the MHRA said.

The fake medicine was also missing Lot codes on the end flap of the outer packaging and the inner foil safety seal did not have the words ‘sealed for your protection’ on it.

The MHRA said it had not yet found the fake drug in the UK, but warned patients could still buy it online.

MHRA head of Enforcement Mick Deats said: “Buying weight loss medication from unregulated websites is a dangerous way to slim down.”

“You don’t know what you’re taking and your condition is not being monitored by a healthcare professional,” he added.

To report a counterfeit medicine call the MHRA Counterfeit Hotline on 020 7084 2701 or email them here.