“Stroke” is a medical term commonly used to mean damage to part of the brain caused by a lack of blood flow. Blood flow may be reduced by a blood clot, an embolus (a clot forming in one place and moving to another place), or a ruptured artery that delivers blood to that part of the brain. “Risk factors” increase the chance that someone will have a stroke. Some of the most common risk factors for stroke include high blood pressure, diabetes, high blood cholesterol, and smoking.
In patients with migraine without aura, taking OCs seems to slightly increase the risk of stroke, particularly in women during their childbearing years. OCs containing low doses of estrogen (35 micrograms or less) do not appear to substantially increase the rate of stroke in women without traditional stroke risk factors. Low-dose OCs also may carry less risk of life-threatening events than can occur with pregnancy. There is, however, a greater risk of stroke with OC use in older women (over 35 years of age) and in those who smoke, have hypertension or diabetes, or have a history of stroke or transient ischemic attack (also known as “TIA”).
Recent data suggests that combined OC pills, including those with low estrogen levels, increase the risk of stroke in women with migraine even if no other risk factors for stroke exist. 4 The absolute risk of stroke in this population, however, is small. Therefore, it is difficult to make any definitive recommendations.
Women who have migraine with aura (especially prolonged or complicated auras involving numbness, weakness or loss of vision) may have an increased risk of a stroke. How high is that risk? Unfortunately, no one knows for sure; some estimates put it at around 14 times the risk of someone in the general population. 5 In the United Kingdom, OCs are not traditionally prescribed for women who have migraine with aura. In contrast, some clinicians think that aspirin and migraine-preventing medications may give some protection against stroke for migraine sufferers. Women with migraine who take OCs and develop aura for the first time, who have more severe aura symptoms, or whose headaches worsen significantly should discontinue using OCs and contact their doctor immediately.
If the decision is made to use OCs, using a lower dose of estrogen and taking it continuously (skipping the placebo pill or pill-free week) may be the most effective way to avoid worsening headaches. Many experts also recommend choosing an OC that has stable levels of hormones rather than changing doses throughout the month. This is based on the theory that increases and decreases in circulating levels of estrogen may not be well tolerated by women with headaches influenced by hormones.
The question remains whether putting these two things together (migraine and using OCs) increases the risk of a stroke to unacceptable levels. Most experts agree that women who have migraine without aura, and have no risk factors for stroke, can probably safely take OCs. The risks of unintended pregnancy for those women may outweigh the small increase in risk of stroke. In migraine with aura, there is differing opinion among experts. If the aura symptoms are not complicated and the woman has no other risk factors for stroke, some experts would be comfortable using low-dose OCs. In light of this uncertainty, using OCs in patients with migraine is a decision that needs to be made on an individual basis and discussed with the woman’s treating physician.