Birth control pills: Learn the types and answers to common questions

For more than 60 years, a tiny pill swallowed once a day has been an effective way to help prevent pregnancy. By age 49, nearly 80% of women in the US have used a birth control pill at some point in their life.^1,2,3,4

What used to be called “the pill” has come a long way. Decades of research has made hormonal birth control even more safe and effective.^5,6

For anyone considering oral contraceptives for the first time or maybe switching from another method of birth control, the pill may be an option to consider. Talk to your health care provider and learn more about your different options below.

In this article:

• What types of birth control pills are there?
• What are some birth control pill side effects?
• Do birth control pills make a person gain weight?
• How effective are birth control pills?
• How soon do birth control pills work?
• How long can it take someone to get pregnant after they stop using a birth control pill?
• What if someone misses a dose of their birth control pill?

What types of birth control pills are there?

Birth control pills contain synthetic forms of estrogen and progesterone, the body’s natural reproductive hormones. These lower the likelihood of becoming pregnant in different ways. Currently, there are two major categories of pills:

1. Combination pills have a type of estrogen and a progestin, a category of laboratory-made progesterone. They are the most common type of birth control pill. They work by stopping ovulation, which means the ovaries won’t release eggs for sperm to fertilize. Progestin also triggers the mucus that lines the cervix to thicken. That makes it harder for sperm to travel up reproductive pathways to reach an egg.^7,8

Combination pills must be taken every day whether or not someone plans to have sex. Remember to read the product label instructions and talk to your health care provider when starting a new type of birth control.

A newer prescription oral contraceptive combines drospirenone and a different form of estrogen called estetrol.⁹ This newer oral contraceptive has a different safety profile, which might make it an option for certain women with higher risk of blood clots. Check with your health care provider.^10,11

2. Progestin-only pills (also known as POPs or mini pills) contain only progestin.¹² Doctors are more likely to prescribe the mini pill for women who may have other health issues that can be affected by taking combination birth control pills. These might include diabetes, heart disease, high blood pressure, migraines with auras or a history of a blood clots.^13,14

Traditional progestin-only pills come in 28-day packs without hormone-free pills, so they must be taken continuously.^15,16 Even taking the hormone daily, a person may get their period in the fourth week or have irregular bleeding or spotting throughout the month.^17,18,19

Because the mini pill has less effect on ovulation, it is especially important to take it every day and at the same time each day.²⁰ A missed dose happens when a person forgets to take the mini pill within three hours of their normal time.^21,22

Another form of progestin, the drospirenone-only pill, may also be an option, especially for women who experience irregular bleeding with the mini pill.²³ It comes in a 28-day pack with four inactive pills.^24,25 It does a better job of suppressing ovulation than a traditional mini pill.²⁶ While a person should still take the pill at the same time each day, it has a wider window for missed doses than a traditional mini pill.^27,28

An over-the-counter oral contraceptive, known as Opill, was recently approved by the Food and Drug Administration (FDA) and is now available to buy.²⁹ Its active hormone is norgestrel, a type of progestin. Like the mini pill, it will thicken cervical mucus but not suppress every ovulation in women, and it must be taken at the same time every day.³⁰

What are some birth control pill side effects?

Birth control pills are generally safe and effective, but a few common side effects include the following:

• Breast tenderness
• Headache
• Mood changes³¹
• Nausea
• Spotting or bleeding between periods

Most side effects are mild and may subside after a person’s been taking the pill for a while.^32,33

Less commonly, some may develop high blood pressure. The pill, particularly those with estrogen, have also been linked to blood clots, heart attacks and strokes.³⁴ However, most if not all currently available pills contain less than 35 micrograms of estrogen, making them far safer than earlier versions. If you are older than 35 and smoke or if you have a history of blood clots or breast cancer, your health care provider may advise you not to take combination birth control pills.^35,36

In any case, it’s important to talk with your health care provider or gynecologist regularly if you take these pills or plan to take them. And be sure to share any side effects or irregular bleeding.

Do birth control pills make a person gain weight?

Oral contraceptives have not been shown to cause significant weight gain or loss.³⁷ Some people may gain a little weight, but, in general, we also gain weight as we get older.³⁸

How effective are birth control pills?

The good news: If used perfectly without missing a dose, oral contraceptives are more than 99% effective. That means less than 1 in 100 women who take the pill become pregnant each year.^39,40,41 Be sure to read the product label for directions and safety information.

Of course, no one is perfect. A person may miss a dose, misplace their pill pack or forget to refill a prescription. So effectiveness drops to 93% with what researchers call “typical use” when products aren’t used as directed.^42,43,44

A few medications can also interfere with birth control pills. The most common are seizure medications, like topiramate. The antibiotic rifampin,⁴⁵ the antifungal griseofulvin⁴⁶ and the herb St. John’s wort⁴⁷ are other things that may make birth control pills less effective.⁴⁸ Make sure to tell your health care provider about any current medications or supplements.

On the topic of effectiveness, remember that oral contraceptives don’t guard against sexually transmitted infections (STIs).⁴⁹

How soon do birth control pills work?

Oral contraceptives need some time to become effective — from two to seven days, depending on the type of pill and where in the menstrual cycle a person is when they start them.⁵⁰ So, for the week after starting either the combined or mini pill, consider using a barrier birth control method, such as a condom or contraceptive sponge.^51,52

How long can it take someone to get pregnant after they stop using birth control pills?

When a person stops using birth control, it’s possible to get pregnant right away, even if they haven’t had their period, yet.⁵³ Someone can go off birth control at any point in their cycle, and their body will begin to return to the way it was before using birth control. They may have irregular periods for a few months or experience spotting or bleeding between periods.⁵⁴ They may find it helpful to track their cycle  after stopping birth control.

What if someone misses a dose of their birth control pill?

Getting back on track depends on which oral contraceptive a person takes and whether they’re off schedule by a few hours or a few days. Read the package instructions or speak to your health care provider if this happens.

This content is for informational purposes only and is not medical advice. Consult your health care provider before taking any vitamins or supplements and prior to beginning or changing any health care practices.