New anti-migraine drugs that have fewer side effects than existing treatments could be on the market within three years, scientists said yesterday.

They have been developed thanks to improved understanding of the mechanism that makes the brain over-react to stimuli and will usher in a new era in management of the condition, experts say.

Migraine is a hereditary illness which affects an estimated six million Britons – or 15 per cent of all adults. It is caused by an "oversensitive" brain which reacts to triggers such as fatigue, hunger, stress or the weather with a throbbing, one-sided headache, often accompanied by nausea and visual disturbances. Three times more women than men are sufferers.

One of the new drugs – a rescue treatment known only by its code MK0974 – interrupts the sequence of chemical reactions in the brain that cause a migraine at a different point from existing drugs.

Studies have shown that the brain releases the chemical calcitonin gene-related peptide (CGRP) during a migraine. Existing drugs, called triptans, block the release of the chemical. The new drug, known as a CGRP antagonist, blocks uptake of the chemical by neighbouring nerve cells.

Final trial results to be presented later this month to the American Headache Society will show that MK0974 reduces pain and is better at preventing the return of the migraine over 24 hours than existing triptan drugs, of which the best known is sumatriptan.

Peter Goadsby, leader of the headache group at the Institute of Neurology, University College London, said yesterday: "[MK0974] is very well tolerated and does really well compared with current treatments. It is going to be an important advance. We are well on the way to having a totally novel way of treating migraine."