Most adverse drug reactions not reported in UK

A least one quarter of a million people in Britain are admitted to hospital each year because of a harmful reaction to a drug, at a cost of nearly half a billion pounds, according to a report on Thursday.

An adverse drug reaction (ADR) is an unwanted effect following treatment with a medicine or combination of drugs. It can range from a skin rash to respiratory failure, heart attack and sudden death.

"ADRs accounted for 4 percent of hospital bed capacity and resulted in projected annual cost to the National Health Service of 466 million pounds," the British Medical Association said in the report.

It added that just over two percent of patients admitted to hospital with an ADR died, according to a study in 2004.

Professor Charles George, chairman of the board of science at the BMA, said although drugs are tested before they are approved, there is the possibility of harmful effects occurring in patients.

Clinical trials are limited in the number of people involved and may not identify safety issues in a very large population or delayed reactions.

Mixing drugs and using them with alternative and herbal medicines such as St. John's Wort, which is used to relieve mild depression, can also produce unwanted results. "Continued vigilance is essential once a drug has been licensed and marketed," George told reporters.

"Although medicines are marketed for an intended action, they may have other actions which only become apparent after marketing," he added.

The report emphasized the need for doctors, nurses, pharmacists and patients to report adverse drug reactions to protect health and save lives. It also explained how to report them.

Dr. Vivienne Nathanson, the head of BMA ethics and science, said only about 10 percent of adverse reactions are formally reported, for a variety of reasons.

Doctors may be confused about the reporting system. They may think the side effect is well known or too trivial to report. It can also be difficult to link an adverse event to a particular drug.

Nathanson stressed the importance of reporting any adverse drug reactions in children and the elderly.

Very few drugs are tested on children so their effects are not well known. The elderly may be taking multiple medications and may react differently from younger adults to treatments.