London: Xenical, an obesity drug previously only prescribed to patients by a doctor, is to go on sale at branches of Botts, the chemist.

Although Boots says it will carry out detailed patient screening GPs expressed serious concerns about the scheme as the shop would not have all the information.

Xenical, also known as Orlistat, inhibits the absorption of fat in the intestine so the body excretes it instead. Users must stick to a low-fat diet, or face unpleasant side effects, including loss of bowel control.

It will be available at 100 branches of Boots across the country. Patients will have to enrol in the company’s weight loss programme, which costs £10 a week. They must also be classed as obese – defined as a body mass index of 30 more. As well as being able to get Xenical, they will also be advised on nutrition and how to increase their activity levels. Blood pressure and glucose levels would also be measured before they receive the medication.