A DRIVER blamed a head-on car crash on a delayed reaction to a wasp sting despite showing no symptoms when examined by paramedics, a court heard.

David Boyes, 22, said his Vauxhall Corsa veered on to the wrong side of the road because he passed out while suffering a delayed allergic reaction to a sting.

An allergy expert yesterday told a jury at Exeter Crown Court that there had never been a recorded case of a delayed reaction without any symptoms being felt at the time of the sting.

Dr Timothy Howe said medical records from those who treated Boyes, of Lound Nook, Belper, after the crash on the A35 near Axminster, showed no indication that he was suffering an anaphylactic reaction.

Boyes was returning home after visiting relatives in Devon following a cricket tour in Weymouth, Dorset, when he crashed in Gammons Hill, Kilmington, in July 2009.

His car drifted on to the wrong side of the road and hit another Corsa, being driven by Sarah Farquhar, 24, on her way home from work.

She suffered two broken legs, broken toes and a broken collar bone, and spent three weeks in the Royal Devon and Exeter Hospital after being airlifted from the scene.

The prosecution says Boyes may have been distracted by his iPod, which was found on the passenger seat, paused in mid-song.

A mobile phone was found in his car and police said that a text message had been received from it nine minutes before the accident.

Boyes denies dangerous driving.

Prosecution medical expert Dr How, consultant immuno therapist at Derriford Hospital, Plymouth, said Boyes' medical notes showed he had suffered a severe reaction to two wasp stings in 2001, when he was 11.

He said Boyes had needed hospital treatment then and had continued to be prescribed adrenaline pens to inject himself in case of another sting.

But he said Boyes' account of being stung at noon on the day of the crash and then suffering a severe reaction five hours later was unlikely.

He said medical notes made by paramedics and staff at the Royal Devon and Exeter Hospital showed no indication of an allergic reaction.

He said: "For an insect sting like a wasp sting, the most severe reaction will normally happen within 30 minutes.

"Sometimes it will resolve itself and then come back, on average eight to ten hours later.

"I have never seen a case of this happening when there has been no initial reaction in a wasp sting and I cannot find any example in the medical literature.

"There is a section of the form filled in by paramedics at the scene about allergies which is marked 'none'."