While steroid inhalers may help asthmatics, they are little use for patients with chronic obstructive pulmonary disease (COPD), say experts.

The inhalers can help reduce the inflammation which narrows the airways of asthmatics, making it hard to breathe.

The steroids also make the airways less likely to react to the allergens which can trigger asthma attacks.

They are, however, widely prescribed against COPD, a mostly smoking-related combination of emphysema and chronic bronchitis.

The illness progressively reduces the effectiveness of the lungs, leading to extreme shortness of breath.

Despite COPD being related to inflammation of the airways, the latest evidence suggests that the steroid inhalers have little effect.

The study, published in the New England Journal of Medicine, found no long-term benefit - the gradual reduction in lung function continued at the same rate in patients given the inhalers as those not given them.

Fewer short-term flare-ups

The researchers, coordinated by the Mayo Clinic in the US, looked at 1,116 patients, all with mild to moderate cases of COPD.

They found that while those being treated had slightly fewer short-term flare-ups of the condition which required A&E treatment, there was no slowing down of the progressive disease.

In addition, some of the better-known side effects of long-term steroid use were noted, such as a slight reduction in bone density, which could make fractures more likely.

Dr Paul Scanlon, leading the study, said: "The findings raise questions about the appropriateness of the current frequent use of this medication for COPD.

"Although inhaled corticosteroids continue to give substantial benefits to asthma sufferers, the research suggests that for COPD we need to weigh any potential benefit against the long-term adverse effects on a case-by-case basis."

The corticosteroids differ from the "reliever" inhaler also used by many asthmatics and COPD sufferers to reduce their symptoms.