A class of commonly prescribed asthma drugs may actually cause severe asthma attacks and even death, doctors have said.

Experts in respiratory care have called on the Europe’s drug watchdog, the European Medicines Agency, to warn patients of the dangers of long-acting beta-agonist (LABA) drugs, which are used to treat the more severe forms of asthma.

Writing in an editorial in the Journal of the Royal Society of Medicine, Vassilis Vassiliou, of the University of Cambridge, said that the drugs, which include Serevent, salmeterol and formoterol, should not be used on their own, and were safe only when used in conjunction with a steroid inhaler. However, he said that more and more people were using them as a single treatment.

Asthma affects more than five million people in Britain and is responsible for about 70,000 hospital admissions and 1,400 deaths a year.

Dr Vassiliou said: “We are seeing an increasingly worrying trend where chronic asthma sufferers, mainly children, are being treated solely by LABA drugs.

“LABA on its own is not safe and this monotherapy is neither supported by current evidence nor encouraged by the current British Thoracic Society guidelines.”

Serevent, which is the GlaxoSmithKline brand form of salmeterol, is recommended for severe forms of the disease because its effects are long- lasting and can be taken twice a day. When inhaled, both it and formoterol help to relax the muscles around the airways of the lungs, which when tight cause wheezing. Neither drug should be used for sudden asthma attacks.

Dr Vassiliou, who also works at Addenbrooke’s Hospital, and Christos Zipitis, of Burnley General Hospital, studied the results of GlaxoSmithKline’s Salmeterol Multicentre Asthma Research Trial, which looked at salmeterol’s effect on more than 26,000 asthma sufferers.

The trial was halted in 2003 after interim results showed that there were more respiratory-related deaths among patients on salmeterol than those using a placebo.

Last year the US Food and Drug Administration gave a warning that LABA drugs may be linked with asthma-related deaths and serious asthma attacks, and told drug companies to inform doctors and patients about the possible risks.

“It is crucial the European Medicines Agency follow (this lead),” Dr Vassiliou said. “While there is provision in the British Thoracic Society guidelines for LABA drugs to be discontinued if they are not deemed useful after a trial period, this is not being reinforced.

“It is critical that current evidence on asthma drugs is incorporated in clinical practice.”

However, other asthma experts disagree, pointing out that the LABA concerns are based on a single study and that repeated warnings gave the impression there was a growing body of evidence against the drugs.

Martyn Partridge, the chief medical adviser at Asthma UK, said that the drugs were of benefit to most people and that any possible risk highlighted might be because of genetic or racial differences between users. However, he said that use of salmeterol on its own — without a steroid inhaler such as Becotide — should be avoided.

“Such multiple reanalyses of already published data gives the impression of multiple new studies all showing the same thing, which is not actually what is happening — but this is certainly a situation where we ‘must watch this space’,” Professor Partridge said.