People who experience migraines are more likely to experience blood clots in their veins, according to scientists.
These blood clots are potentially fatal if they dislodge and travel to the heart and lungs.
Venous thrombosis is where blood clots form in a vein, possibly limiting blood flow and causing swelling and pain. It is not clear why migraine and venous thrombosis or thromboembolism may be linked.
According to the study in the medical journal of the American Academy of Neurology, one theory is that the blood of people with migraine may be more prone to clotting.
High-resolution ultrasounds were used on 574 people aged 55 and over in an Italy-based study. The ultrasounds were used to scan arteries in their necks and thighs for atherosclerosis, or hardening of the arteries.
Of the participants, 111 people had migraine. A total of 21 people with migraine also had one or more instances of venous thrombosis, it was found. In comparison, 35 people without migraine had the condition.
The study from the Innsbruck Medical University in Austria also found that people with migraine are not more likely to have hardening or narrowing of the arteries, which is contrary to a current theory.