Early treatment with drugs called triptans can prevent migraines or reduce their severity, a conference has heard.
Dr Werner Becker, of the University of Calgary in Canada, gave evidence about triptans to a meeting of the American Headache Society in Washington DC.
He said: "We found that headache prevention is possible when a triptan is administered during the premonitory period. And those that did occur appeared to be milder."
He reported on his findings as fellow British and Canadian scientists said they had identified a defective gene in a family of migraine sufferers, raising the prospect of a pill to tackle the condition.
The researchers found pain centres could be set off in the brain when the gene, known as TRESK, does not function correctly.
Professor Guy Rouleau, from the University of Montreal, said: "We may be moving toward developing a pill that would block the brain's pain channel that reacts to stimulation and causes pain in migraine."
Prof Rouleau addressed around 500 experts at the annual meeting of the American Headache Society.
The delegates heard that as many as a third of sufferers experience a warning visual disturbance, called an aura, which occurs before the onset of the headache.