Migraines aren’t everyday headaches. Along with intense throbbing pain, they can cause nausea, light sensitivity, and sometimes auras, which are flashes of light or other strange sensations. More than 40 percent of women in America have had to deal with migraines at one time or another. Many of these women are in their reproductive years and use hormone-based birth control methods like the pill.

For some women, taking birth control pills can bring relief from migraines. For others, the pill intensifies headaches. If you get migraines and are considering taking birth control pills, here are a few things you should know.

Birth control pills are typically taken to prevent pregnancy. Most pills contain man-made versions of the female hormones estrogen (ethinyl estradiol) and progesterone (progestin). These are called combination pills. The minipill contains only progestin. The amount of estrogen and progestin in each type of birth control pill can differ.

Normally, a surge of estrogen during your menstrual cycle causes you to ovulate and release a mature egg. The hormones in birth control pills keep estrogen levels steady to prevent an egg from being released. These hormones also thicken the cervical mucus, making it hard for sperm to swim through. They can also change the lining of the uterus so that any egg that is fertilized can’t implant and grow.

Sometimes, birth control pills help migraines. Sometimes, they make headaches worse. How birth control affects migraines depends on the woman and on the level of hormones present in the pill she takes.

A drop in estrogen levels can trigger migraines. That’s why some women get headaches just before their period, which is when estrogen levels dip. If you have these menstrual migraines, birth control pills might help prevent your headaches by keeping your estrogen levels stable throughout the menstrual cycle.

Other women start getting migraines or find that their migraines get worse when they take combination birth control pills. Their headaches may lessen after they’ve been on the pill for a few months.

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In addition to triggering migraines in some women, birth control pills can cause other side effects. These can include:

  • bleeding between periods
  • breast tenderness
  • headaches
  • mood changes
  • nausea
  • swelling of the gums
  • increased vaginal discharge
  • weight gain

Both birth control pills and migraines can very slightly increase your risk of stroke. If you get migraines with aura, taking combination pills can increase your stroke risk even more. Your doctor will likely suggest that you take progestin-only pills.

An increased risk of blood clotting is also associated with hormonal birth control. This may lead to:

  • a deep vein thrombosis
  • a heart attack
  • a stroke
  • a pulmonary embolism

The risk for blood clotting is low unless you:

  • are overweight
  • have high blood pressure
  • smoke cigarettes
  • are on bed rest for extended periods

If any of these apply to you, speak with your doctor about your options for birth control. They may be able to recommend a suitable option with less risk.

Combination birth control pill packs contain 21 active pills with hormones and seven inactive, or placebo, pills. The sudden drop in estrogen during your inactive pill days may trigger migraines. One solution is to switch to a pill that’s lower in estrogen, so you don’t experience that sharp hormone drop. Another option is to take a pill that contains a low dose of estrogen on your placebo pill days.

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Switching to a continuous dose birth control pill such as Seasonale or Seasonique can also help. You’ll take active pills for three 28-day cycles, followed by a four- to seven-day break. Another continuous option is Lybrel, which has only active pills and no break. The steady dose of estrogen these pills provide should make you less likely to have migraines.

If the pill makes your migraines worse or happen more often, you may need to switch to another birth control method. Talk to your doctor about finding a new type of protection before going off the pill. Don’t just stop taking it. About 20 percent of unplanned pregnancies are due to women stopping their birth control without having a backup plan.

Your doctor will help you decide which pill is best for you based on your medical history. Even though a combination pill may help your migraines, it may not be the safest option. You can also explore other contraceptive options such as intrauterine rings, vaginal rings, and injections.