A weight loss drug used by thousands of Britons has been rejected by US safety officials because of an increased risk of suicide.
The drug works by reducing appetite
Rimonabant, launched in the UK last summer, has been shown to aid weight loss by reducing appetite.
But a committee advising the US Food and Drug Administration (FDA) voted to ban the pill, saying the manufacturers had failed to show it was safe.
European regulators will review the drug's safety at an upcoming meeting.
Around 37,000 Britons have been prescribed rimonabant which can help users lose up to 10% of their body weight.
The drug is currently recommended for obese patients with a risk of developing diabetes or cardiovascular disease.
It works by blocking receptors in the part of the brain that regulate food intake and the body's ability to break down sugars and fats in the blood.
The National Institute of Clinical and Health Excellence (NICE) is currently appraising the drug for use on the NHS.
The US committee of experts reviewed studies of rimonabant conducted around the world.
They told an FDA hearing that the drug is associated with an increased risk of suicidal thoughts even in those with no history of depression.
Studies had also highlighted significant increases in anxiety, insomnia, and panic attacks in patients given 20 mg of rimonabant compared with placebo.
A recent review of rimonabant by the Cochrane database concluded that more rigorous studies of efficacy and safety were required for a drug where the weight loss is "modest".
The committee warned: "The evidence for increased suicidal tendencies and depression is of particular concern for a drug targeted toward the obese, a population that has been shown to have a significantly higher incidence of depression and eating disorders compared to non-obese individuals."
The FDA is due to consider the panel's decision in July.
Manufacturer's Sanofi-aventis, said they would continue to work closely with the FDA to address the committee's recommendations.
A recent review by the Drug and Therapeutics Bulletin said the drug had not been effectively compared with other, cheaper weight loss drugs, such as Xenical (orlistat) and Reductil (sibutramine), which are both approved for NHS use.
COST OF WEIGHT LOSS DRUGS
Rimonabant: £720 a year
Orlistat: £520 a year
Sibutramine: £480-£570 a year
Dr Ian Campbell, medical director of the charity Weight Concern, said UK experts had also raised concerns about the side effects of the drug, namely anxiety and depression, but the increased risk of suicide was small.
"You have to balance the risks with the advantages of quality of life improvement.
"Rimonabant has a role, it should be used with care but directed towards the right patient it can be effective and safe."
He added that the drug should not be used in people being treated for depression or with a recent history of depression.