Hayfever patients 'drive worse than drinkers'

Drivers on newer hayfever drugs were less dangerous

Patients taking old-fashioned antihistamine drugs performed worse than drinkers in a driving simulator.

The research, carried out at the University of Iowa, highlighted the dangers of drowsiness and lack of attention caused by the "first generation" drugs.

A more recent hayfever drug caused far fewer problems, the study showed.

The older drug used was diphenydramine, which is still used in popular antihistamines.

Patients taking a standard dose were compared with those taking a dose of a the newer drug, people given a quantity of alcohol and people given nothing.

The subject's performance was worst after taking diphenhydramine.

However, performance after taking the newer drug, fexofenadine, was comparable with those who had taken nothing.

All of the subjects were licenced drivers with some sort of pollen allergy.

The driving simulator tested their ability to follow a lead car that changed its speed randomly.

Bad driving

Those who had been given alcohol - but were still under the legal limit - performed well, but drove closer to the car and had less steering control.

However, those on the older antihistamine had greater trouble steering and crossed the white line in the centre of the road far more frequently.

Dr John Weiler, who carried out the research, said: "We were surprised to find that this antihistamine has more impact on driving performance than alcohol does."

The second-generation antihistamine causes less impairment because its active ingredients cannot get out of the blood into the brain, whereas the older antihistamines can breach this "blood-brain barrier".

In many US states, driving under the influence of "sedating medications" is outlawed.

However, in the UK, such medicines only have packet warnings not to drive or operate machinery should drowsiness occur.

Dr Martin Stern, a consultant clinical immunologist from Leicester General Infirmary, who specialises in allergies, said that the use of first-generation antihistamines was "distressingly common".

There were only a particular few types of allergy which demanded these drugs.

"It's pure conservativism by doctors, and it's time they got the message.

"Doctors who prescribe these sedative anti-histamines when they don't need to will end up getting sued."

While the first generation antihistamine diphenydramine is more common in US products, UK consumers still take first generation sedating antihistamines such as Piriton.

Other studies have demonstrated the links between sedative antihistamines and poor driving.

And another showed that children giving the drugs suffered academically.