Birth control pill FAQ: Benefits, risks and choices

Get the facts on common concerns and questions about birth control pills.

By Mayo Clinic Staff

If you take birth control pills (oral contraceptives), you're probably happy with the convenience and reliability. Still, you may have questions about how birth control pills could affect your health, the benefits and risks of birth control pills, and newer options available.

Can I use birth control pills to delay or stop my period?

Yes, you can. Birth control pills were once only packaged as 21 days of active hormone pills and seven days of inactive pills. While you take the inactive pills, menstrual-like bleeding occurs.

Today you have many more options — from regimens with 24 days of active pills and four days of inactive pills to regimens that are all active pills.

Some extended-cycle pill regimens have active hormone pills every day for three months, followed by a week of inactive or low-dose estrogen pills. You experience menstrual-like bleeding during that week. Other extended-cycle regimens involve taking active pills continuously for one year, which can stop all menstrual-like bleeding.

Continuous or extended-cycle regimens have several potential benefits. They prevent the hormone changes that are responsible for bleeding, cramping, headaches and other period-related discomforts. They allow you to skip a period during important events or trips. If you experience iron deficiency due to heavy menstrual bleeding, using continuous regimens can reduce bleeding.

Unscheduled bleeding and spotting often occur during the first few months on continuous or extended-cycle regimens, but usually stop with time.

To prevent having a period, can I use ordinary birth control pills or do I need special pills?

There are birth control pill regimens designed to prevent bleeding for three months at a time or for as long as a year. But it's possible to prevent your period with continuous use of monophasic birth control pills — pills with the same hormone dose in the three weeks of active pills. To prevent your period with these pills, don't take the inactive pills and start right away on a new pack.

If I plan to have a baby, how soon after stopping birth control pills can I conceive?

Usually ovulation begins again a few weeks after stopping birth control pills.

As soon as you ovulate again, you can get pregnant. If this happens during your first cycle off the pill, you may not have a period at all. Take a pregnancy test if you've had unprotected sex and your period hasn't returned.

Is there an advantage to waiting a few months after stopping the pill before trying to conceive?

Conceiving immediately after stopping the pill does not increase your risk of miscarriage or harm to the fetus. The hormones in birth control pills don't remain in your system.

Usually periods start again a few weeks after stopping the pill. However, if your periods were infrequent before you started taking the pill, they will likely be that way again after you stop taking the pill. It may take a couple of months before you return to regular ovulation cycles.

After stopping the pill, if you're not ready to conceive, consider using a backup form of birth control.

What happens if I stop taking the birth control pill and my period doesn't come back?

If you don't have a period for several months, you may have what's known as post-pill amenorrhea. The pill prevents your body from making hormones involved in ovulation and menstruation. When you stop taking the pill, it can take some time for your body to start producing these hormones again.

Menstrual periods typically resume within three months after you stop taking the pill. But if you took the pill to regulate your menstrual cycles, it may take several months before your period comes back.

If you don't have a period within three months, take a pregnancy test to make sure you're not pregnant and then see your doctor.

Will a pregnancy test be accurate if I'm taking the birth control pill?

You can get accurate results from a pregnancy test while you're on the pill. Pregnancy tests work by measuring a specific pregnancy-related hormone — human chorionic gonadotropin (HCG) — in your blood or urine. The active ingredients in birth control pills don't affect how a pregnancy test measures the level of HCG in your system.

What happens if I take birth control pills while pregnant?

Don't worry if you kept taking your birth control pill because you didn't know you were pregnant.

Despite years of this accident happening, there's very little evidence that exposure to the hormones in birth control pills causes birth defects. Once you learn that you're pregnant, stop taking the birth control pill.

Can I use several birth control pills at once for emergency contraception?

It's possible to use standard estrogen-progestin birth control pills for emergency contraception, but check with your doctor for the proper dose and timing of the pills.

Certain types of pills are specifically designed to keep you from becoming pregnant if you've had unprotected sex. These medications are sometimes referred to as the morning-after pill.

Morning-after pills contain either levonorgestrel (Plan B One-Step, EContra One-Step, others) or ulipristal acetate (ella, Logilia).

Levonorgestrel pills are available over-the-counter to anyone of any age. Levonorgestrel pills work best when used as soon as possible — and within three days — after unprotected sex.

Ulipristal acetate is a nonhormonal medication available only by prescription. This medication is taken as a single dose within five days after unprotected sex.

A copper intrauterine device (IUD) or an IUD containing 52 milligrams of levonorgestrel may also be used for emergency contraception. Ideally, these IUDs should be placed by your doctor within five days of unprotected intercourse.

Does how much I weigh reduce the effectiveness of emergency birth control pills?

If you are considered obese with a body mass index (BMI) of 30 or more, emergency contraception may not be as effective — especially if you use levonorgestrel. You could still become pregnant after using levonorgestrel for emergency contraception. BMI is not as much of a concern when using ulipristal. Use of an IUD for emergency birth control is not affected by body weight.

I have taken birth control pills for years and want to stop. Can I stop at any time or should I finish my current pill packet?

In terms of your overall health, it makes little difference when you stop taking the pill. When you finally do stop the pill, you can expect some bleeding, which may change the rhythm of your menstrual cycle. But you can stop at any time.

Can I get pregnant during the week of inactive pills?

Taking the inactive pills doesn't put you at higher risk of unintended pregnancy. If you're taking birth control pills exactly as directed, they're about 99% effective at preventing pregnancy.

But if you miss a pill — or several pills — during a cycle, you might be at higher risk of unintended pregnancy during that cycle. To be safe, use a backup form of contraception, such as a condom, especially if you miss several pills during a cycle.

Do birth control pills cause weight gain?

This is a common thought. But studies have shown that the effect of the birth control pill on weight is small — if it exists at all.

Instead, you may be retaining more fluid, which can make you feel as if you've put on weight, particularly in your breasts, hips and thighs. The estrogen in birth control pills does affect fat (adipose) cells, making them larger but not more numerous.

How do birth control pills affect cancer risk?

Most data show that birth control pills don't increase your overall risk of cancer.

Scientific evidence suggests using birth control pills for longer periods of time increases your risk of some cancers, such as cervical cancer, but the risk declines after stopping use of birth control pills.

Regarding breast cancer risk, the results are mixed. Some studies show a link between birth control pill use and a slight increase in breast cancer risk, but the risk is very low. Other studies have shown no significant increase in breast cancer risk. Risk appears to decrease over time after discontinuing birth control pills. If you have a family history of breast cancer, birth control use does not appear to increase the risk.

The birth control pill may decrease your risk of other types of cancer, including ovarian cancer, endometrial cancer and colon cancer — and this benefit may persist for years after you stop the pill.

Do birth control pills affect cholesterol levels?

Birth control pills can affect your cholesterol levels. How much of an effect depends on the type of pill you're taking and what concentration of estrogen or progestin it contains. Birth control pills with more estrogen can have a slightly beneficial overall effect on your cholesterol levels. In general, though, the changes aren't significant and don't affect your overall health.

Do birth control pills affect blood pressure?

Birth control pills may slightly increase your blood pressure. If you take birth control pills, have your blood pressure checked regularly. If you already have high blood pressure, talk with your doctor about whether you should consider another form of birth control.

What is the risk of blood clots when taking birth control pills?

The estrogen contained in combination hormone birth control pills and in the ring or patch is not recommended if you have a history of blood clots — venous thromboembolism (VTE) — or if you are at high risk of blood clots. A progestin-only form of contraception — such as the minipill or an implant — an IUD or a barrier method is a better choice. Progestin or progesterone also can increase the risk of blood clots, but the risk is less than with estrogen.

Can I continue taking birth control pills if I'm older than age 35?

If you're healthy and you don't smoke, you can continue taking birth control pills after age 35.

However, birth control pills aren't recommended if you're 35 or older and you smoke because of the risk of heart and blood vessel (cardiovascular) disease. In that case, you need to quit smoking before you can safely continue using birth control pills.

Can antibiotics decrease the effectiveness of birth control pills?

Antibiotics do not interfere with the effectiveness of birth control pills — except in the case of one antibiotic, rifampin (Rimactane). Rifampin does decrease the effectiveness of birth control pills in preventing ovulation, but this antibiotic isn't widely used today.

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May 10, 2023 See more In-depth