The drug is injected straight into the bloodstream rather than swallowed.
Each injection contains a high dose of one gramme of aspirin, more than ten times the amount most people would take to soothe a normal headache or joint pain.
New research shows pumping high doses of liquid aspirin into the blood can dampen down pain in patients struck down by migraines that are so severe they end up needing hospital treatment.
Doctors behind the study, carried out at the University of California in San Francisco, now hope the therapy can be used more widely to help thousands more sufferers with less severe headaches.
It could also lead to substantial savings for the NHS, as aspirin costs around a third of the price of more expensive migraine pills, known as triptans.
The news of research into the aspirin jab comes as scientists have also discovered a faulty gene linked to the agonising condition.
Researchers from Oxford University found the gene, called TRESK, in families of sufferers. When it is mutated it can more easily trigger the brain’s pain centres and cause severe headaches, says their report in the journal Nature Genetics.
Migraine affects around one in ten of the UK population, with women affected more than men.
Most people suffer with common migraine, which involves a severe throbbing headache, usually on one side of the head. Loss of appetite, nausea, constipation or diarrhoea are also common symptoms.
Sitting in a quiet, darkened room can help sufferers cope with an attack and over-the-counter painkilling tablets such as paracetamol and ibuprofen can ease mild cases.
But for severe attacks, patients are given triptans, the more powerful prescription drugs that can be swallowed, injected or sprayed up the nose.
Triptans work by restoring the chemical balance in the brain disrupted by migraines.
Yet even these sometimes fail to curb the attacks.
Aspirin works by blocking production of enzymes called cycloxygenases. These are crucial for the release of prostaglandins, hormones that help send pain signals through the nervous system.
Injecting high doses stops this process – without the risk of stomach bleeding that comes with swallowing aspirin tablets. Liquid aspirin has been used as a migraine therapy for several years in some European countries, such as Germany.
But in the UK, it is given only to a small number of patients who receive it on a named patient basis – this is when a drug is used in a different way to that stipulated by its licence and the doctor bears legal responsibility if anything goes wrong.
Aspirin injections are a last resort for sufferers who have failed to respond to all other medications.
However, the latest research, published in the journal Neurology, suggests many more sufferers could benefit.
In the study, the treatment was given to 168 patients aged from 18 to 75 who had been admitted to hospital for severe attacks made worse by medication overuse (many migraine sufferers develop a tolerance to their painkillers and gradually increase their medication; when they try to reduce their drug use, they develop severe withdrawal headaches).
Researchers gave these patients five doses of injected aspirin and measured their pain on a scale of one to ten.
Those scoring one to three had mild headaches, four to seven were moderate and eight to ten severe.
For at least 25 per cent of the treatment period, patients said they had a significant decline in pain – equivalent to a drop of three points on the ten point scale.
For a further 40 per cent of the treatment time they had a modest fall in pain – a drop of one to two points.
Research leader Professor Peter Goadsby, who is also a trustee of The Migraine Trust in the UK, said aspirin injections appear to be just as good as a commonly-used drug, called sumatriptan, in the treatment of acute migraine.
‘We hope to make this inexpensive therapy more available to patients seeking treatment for severe pain,’ he said.
‘There are very good data from placebo-controlled trials that intravenous aspirin has a similar rate of success to six milligrams of injectable sumatriptan in acute migraine.