Are they safe?
Attempts by the pharmaceutical industry to create a safe and effective appetite suppressant have so far failed so there is no evidence to say that they safely help with weight loss.
Two appetite suppressants - sibutramine (Reductil) and rimonabant (Acomplia) - were taken off the UK market in recent years. Both went through clinical trials but once people widely began using them, dangerous side-effects were reported. Side effects from one drug included making the people taking them feel suicidal, while another drug increased the chances of having a non-fatal heart attack or stroke.
Two other appetite suppressants available in the UK, phentermine and diethylpropion, have been around for over 50 years, but can only be obtained with a private prescription, for example from a doctor in a slimming clinic. They are not available on prescription on the NHS. The European Medicines Agency (EMA), which regulates the approval and use of drugs in Europe, once attempted to ban these drugs by taking their licences away. However, an independent manufacturer of the drugs fought the EMA in the European courts and won, overturning the decision.
The only diet medication which is currently licensed in the UK as safe and effective is orlistat, which is a lipase inhibitor. This means that it reduces the amount of energy that you take in from the fat contained in foods that you eat, and the undigested fat is passed along with your faeces. It doesn’t suppress the appetite, but instead works by preventing up to a third of the fat that you eat from being absorbed by the body.
Orlistat (also known as Xenical) is available on prescription, and is prescribed if a doctor or pharmacist thinks that the medicine is suitable for you. You will normally only be prescribed orlistat if you have a body mass index (BMI) of 28 or more.