Suffering with migraines could indicate underlying heart problems, a 19-year investigation involving more than half a million people has suggested.
Research involving both those who were diagnosed with the headache disorder and those who did not report any symptoms found a strong link with cardiovascular problems.
This included heart attacks, strokes, blood clots and irregular heart rates, according to the study in The BMJ (British Medical Journal).
It found the migraine cohort were more likely to suffer a heart attack than those who reported no major headache symptoms - with 25 per 1,000 compared with 17 per 1,000.
Some 45 per 1,000 migraine sufferers also experienced a common form of stroke, compared with 25 per 1,000 of non-migraine sufferers.
In addition, the number of strokes related to haemorrhages was higher in the migraine-suffering cohort (11 compared with six), while 13 compared with 11 suffered peripheral artery disease.
The research also found an increased chance of a symptom related to deep-vein thrombosis (27 per 1,000 migraine sufferers, compared with 18 per 1,000 of the healthy population), and 47 compared with 34 for an abnormally fast heart-rate.
The researchers, from Denmark and the USA, collected patient data between 1995 and 2013.
They compared data from over 51,000 people who had been diagnosed with migraines with more than 510,000 people who were migraine-free.
The average age for migraine diagnosis was 35, with 71% of participants being women.
The report said: "In this nationwide cohort study, migraine was associated with an increased risk of cardiovascular disease.
"This suggests that migraine should be considered a potent and persistent risk factor for most cardiovascular diseases in both men and women."
Migraines are characterised by an intense, throbbing headache, sensitivity to light and noise, nausea, vomiting, low energy, and visual disturbances.
Attacks can last anything from four to 72 hours.
Each year more than 8.5 million people in the UK are thought to experience a migraine, more than the number affected by asthma, diabetes and epilepsy combined.