Although the risks of taking such drugs - known as non-steroidal anti-inflammatory drugs (NSAIDs) - are well established, many sufferers are ignorant about the dangers.

NSAIDs include commonly used drugs such as aspirin. They can make asthma worse and - in some cases - the effect can be fatal.

The Asthma Management in General Practice (AMGP) group says between 5% and 20% of sufferers take NSAIDs.

Knowledge of risks

The group carried out a survey of 700 asthma sufferers to assess their level of knowledge about the risks.

A 1989 study of 92 sufferers attending hospital with an asthma attack found 8% had taken an NSAID.

The new AMGP survey found awareness of the risks had not improved.

It found that even among those sufferers who knew certain painkillers were dangerous, 39% could not name them.

Management concerns

Only 6% of those surveyed had been told paracetamol may be more suitable than other painkillers.

AMGP spokesman Dr David Price said: "The results of this study clearly show that too few asthma sufferers are aware that medicines they take to soothe everyday aches and pains can affect their condition.

"Ideally, people with asthma should use analgesics containing paracetamol as their first choice as these will not make their condition worse.

"If they use other types of painkillers then they must be aware of their possible effects and carefully monitor their asthma."