The American drug regulators, the FDA, have announced that packs of orlistat (the active ingredient in Alli and Xenical) must now carry warnings about the possibility of liver problems.
The move comes after a long-running investigation into 12 reports between 1999 and 2007 of people suffering liver damage. All 12 were living outside of the US, though there was one report of a US citizen suffering from liver problems.
When compared with the number of people taking the medication worldwide, the potential side-effect is extremely rare. Both Roche, who manufacture Xenical, and Alli manufacturers GlaxoSmithKline pointed out that the number of reported problems was extremely small.
The patient information leaflet for both medications now warns that patients should be aware of the symptoms of liver damage, which include itching, yellow eyes, lighter-coloured stools, dark urine and loss of appetite.
Previously the manufacturers had warned that obese patients are more prone to developing liver problems.
UK packaging already contains a warning about liver damage so the ruling will not make a difference to UK patients.
GlaxoSmithKline’s chief medical officer Howard Marsh said that the company wanted people to ‘have the information they need to choose the right weight loss aid for their situation’.