Nearly all sexually active American women ages 15 to 44 have used birth control at least once. For about 26 percent of these women, the method of choice is the birth control pill.

As with any other medication, the birth control pill can cause side effects. Some women may find that their hair thins or falls out while they’re taking the pill. Other women may lose their hair after they stop taking it.

Keep reading for a look at the connection between birth control pills and hair loss, and learn what you can do if hair loss is affecting you.

Birth control pills prevent pregnancy in a few different ways. Most pills contain man-made forms of the female hormones estrogen and progesterone. Normally, a rise in estrogen causes a mature egg to leave the ovaries during a woman’s menstrual cycle. This is called ovulation.

Birth control pills stop the surge in estrogen that causes an egg to be released. They thicken the mucus around the cervix, making it harder for sperm to swim up to the egg.

Birth control pills also change the lining of the uterus. If an egg does get fertilized, it usually can’t implant and grow due to this change.

The following forms of birth control also release hormones into your body to stop ovulation and prevent a pregnancy:

Birth control pills come in two different forms, which are based on the hormones that they contain.

Minipills only contain progestin, a synthetic form of progesterone. Combination birth control pills contain both progestin and synthetic forms of estrogen. Minipills may not prevent pregnancy as effectively as combination pills.

The pills can also differ by hormone dose. In monophasic birth control, the pills all contain the same hormone dose. Multiphasic birth control contains pills with different amounts of hormones.

Birth control pills don’t generally cause any problems for women who take them. Some women do experience mild side effects other than hair loss. These side effects can include:

More serious side effects are rare. These can include high blood pressure and a slightly increased risk of breast, cervical, or liver cancer.

Another serious side effect is an increased risk of a blood clot in your leg or lung. If you smoke, you’re at an even greater risk of this.

Birth control pills can cause hair loss in women who are especially sensitive to the hormones in the pill or who have a family history of hormone-related hair loss.

Hair normally grows in cycles. Anagen is the active phase. During this phase, your hair grows from its follicle. This period can last for two to seven years.

Catagen is the transitional stage when your hair growth stops. It lasts for about 10 to 20 days.

Telogen is the resting phase. During this phase, your hair doesn’t grow. Between 25 and 100 hairs are shed daily in this phase, which can last for up to 100 days.

Birth control pills cause the hair to move from the growing phase to the resting phase too soon and for too long. This form of hair loss is called telogen effluvium. Large amounts of hair can fall out during this process.

If baldness runs in your family, birth control pills can speed up the hair loss process.

Other hormonal birth control methods can also cause or worsen hair loss. These methods include:

  • hormone injections, such as Depo-Provera
  • skin patches, such as Xulane
  • progestin implants, such as Nexplanon
  • vaginal rings, such as NuvaRing

Women who have a family history of hormone-related hair loss may lose hair while on the pill or just after they discontinue it. Some women lose a little bit of hair. Other women lose large clumps of hair or experience a lot of thinning. Hair loss in pregnancy is also hormonally related to hair being in the resting phase for longer periods.

Hair loss can also happen when you switch from one type of pill to another.

Hair loss caused by birth control pills is usually temporary. It should stop within a few months after your body gets used to the pill. Hair loss should also stop after you’ve been off of the pill for a while.

If the hair loss doesn’t stop and you don’t see regrowth, ask your doctor about Minoxidil 2%. It’s the only medicine that’s approved by the U.S. Food & Drug Administration (FDA) to treat hair loss in women.

Minoxidil works by moving hair follicles into the growth phase more quickly. It may take a few months of use before you can see results.

As you consider birth control methods, think about your family history.

If hair loss runs in your family, look for pills that contain more estrogen than progestin. These pills are low on the androgen index, and they can actually stimulate hair growth by keeping your hair in the anagen phase longer.

Low-androgen birth control pills include:

  • desogestrel-ethinyl estradiol (Desogen, Reclipsen)
  • norethindrone (Ortho Micronor, Nor-QD, Aygestin, Lyza)
  • norethindrone-ethinyl estradiol (Ovcon-35, Brevicon, Modicon, Ortho Novum 7/7/7, Tri-Norinyl)
  • norgestimate-ethinyl estradiol (Ortho-Cyclen, Ortho Tri-Cyclen)

Because these pills can have other side effects, talk about the risks and the benefits with your doctor. If you have a strong family history of hair loss, a nonhormonal form of birth control may be a better choice.