Birth Control Pill Overview

Sketched birth control pills.

Birth control pills are one of the most effective contraceptive methods for preventing pregnancy. Commonly referred to as “The Pill,” this type of birth control comes in a variety of forms and can be taken in a variety of different ways depending on the method that works best for the individual. There are two main types of birth control pills: combination pills and progestin-only pills. Combination pills contain the hormones progestin and estrogen. Progestin-only pills contain progestin but do not contain estrogen.¹

What Are Birth Control Pills?

Package of birth control pills in a green container.

Birth control pills come in packages that typically contain a one month’s supply of pills. Combination pills come in either 21-day, 28-day, or 91-day packs. In a 28-day pack, there are 21 “active” pills (containing estrogen and progestin) taken every day for three weeks, and the last four to seven pills are taken as “reminder” or placebo pills that contain no hormones. A 21-day pack is similar to a 28-day pack, except there are no placebo pills taken during the last week. Bleeding occurs during that last week when no hormones are taken. Combination pills can also come in 91-day packs containing three trays of tablets. With this pack, 1 tablet is taken every day for 91 days and ends with a final set of low-dose estrogen or inactive ingredients.² These types of combination pill packs are called “extended” or “continuous use” pills.¹ Progestin-only pills come in 28-day packs. Each pill in the 28-day progestin-only pack is an “active” pill, which means they each contain a small amount of progestin. There are no placebo breaks taken between active pills because progestin-only pills do not control a female’s menstrual period

What Do Estrogen and Progestin Do?

Estrogen and progestin are two naturally occurring sex hormones produced in the human body. In the combination pill, estrogen and progestin are combined and work to prevent ovulation, the process that releases eggs from the ovaries. Estrogen and progestin also prevent pregnancy by changing the mucus at the cervix and altering the lining of the uterus, making it difficult for sperm to enter. Some brands of birth control pills can also treat acne by decreasing the amounts of certain substances in the body that cause acne and by regulating the menstrual cycle.²

Specifically, estrogen is responsible for:

  • Inhibiting the formation of the follicle stimulating hormone (FSH) and of the luteinizing hormone (LH), preventing ovulation
  • Preventing mid-cycle spotting by supporting the uterine lining

Progestin is responsible for:

  • Inhibiting LH production so no egg is released during ovulation
  • Preventing the sperm’s ability to travel by thickening the cervical mucus
  • Limiting the ability of an egg to be fertilized by a sperm
  • Changing the uterine lining to make it difficult for an egg to implant if fertilization does occur?

How to Use Birth Control Pills

Birth control pills are most effective when taken around the same time every day. Progestin-only pills must be taken at precisely the same time each day because they contain only a small amount of progestin that can exit the body in as little as 24 hours, leaving a woman at risk for pregnancy.³ Combination pills allow for a little more temporal fluctuation because the hormones in them are strong enough to prevent pregnancy for a time when the pill is not taken (for example, during the week of inactive pills). It is, however, a good idea to take them as regularly as possible to maximize their effectiveness.¹ We recommend users of the birth control pill set reminders to take the daily pill at the same time throughout the usage.

Which Pill is Right For Me?

Combination Pills

Combination pills tend to be more effective at protecting against pregnancy than progestin-only pills. Combination pills also regulate the menstrual cycle, while progestin-only pills can sometimes make periods more irregular.

Combination pills contain estrogen, which causes side effects that are not typically associated with progestin-only pills. The following are some possible side effects associated with combination pills:

  • Increased risk of blood clots and heart problems
  • Bleeding or spotting between periods
  • Breast tenderness
  • Weight gain
  • Nausea and vomiting
  • Mood changes
  • Headaches
  • Decreased libido

Some of these side effects may occur with progestin-only pills but are more common and more severe with combination pills. In addition, it may take longer for pregnancy to occur or for menstrual cycles to return to normal after you stop taking the combination pill than it would after stopping the progestin only pill.?

Combination birth control pills can increase the risk of developing or worsening certain serious medical conditions. The risks depend in part on a woman’s medical history. Deep vein thrombosis, heart attack, and stroke are some of the major risks associated with combination birth control pills. The combination pill is NOT recommended for women who experience the following:

  • Are over the age 35
  • Smoke cigarettes
  • Have unexplained vaginal bleeding
  • Have breast cancer
  • Have had a heart attack, stroke , or other serious heart problems
  • Have liver disease or liver cancer
  • Have high blood pressure or cholesterol levels
  • Have a history of blood clots
  • Have frequent migraine headaches
  • Have diabetes
  • Are or will be on bedrest for a prolonged period of time

In addition to protection against pregnancy, many women experience health benefits when taking birth control pills. Some positive side effects include:

  • Reduced acne
  • Decreased bone thinning
  • Prevention against cysts in the breasts and ovaries
  • Prevention against endometrial and ovarian cancers
  • Decreased risk for serious infections in the ovaries, fallopian tubes, and uterus
  • Prevention against anemia (iron deficiency)
  • Reduced premenstrual syndrome (PMS), including bloating, headaches, cramping, and dizziness
  • Lightening of menstrual flow¹

Click here to find out more about whether combination pills are right for you.

A variety of different birth control pills.

Progestin-Only Pill

Females who find that the combination pill is not suitable for their needs, may want to consider the progestin-only pill, also nicknamed “the mini pill.” The progestin-only pill is recommended for individuals who:

  • Are breastfeeding; the estrogen in the combination pill inhibits milk production?
  • Smoke cigarettes, are older than 35, or have health problems like heart disease, blood clots, high blood pressure, and migraines. The lack of estrogen in progestin-only pills makes them less likely to cause blood clots.³

Progestin-only pills are just as effective as the combination pill in preventing pregnancy. For women who are unable to take the combination pill due to medical reasons or negative side effects, the progestin-only pill may work better. Women who experience spotting or desire more of the health benefits both estrogen and progestin may prefer the combination pill.

Click here to find out more about progestin-only pills.


You should not take either type of pill if you are pregnant or suspect that you are pregnant. Talk to your doctor if you are experiencing symptoms of pregnancy.

Birth control pills do NOT protect against sexually transmitted infections (STIs). To reduce the risk of contracting or spreading STIs, condoms or other forms of barrier methods should be used.

A doctor shaking another person's hand.


Birth control pills can be purchased at a pharmacy with a prescription from a doctor for about $15-50 dollars a month, depending on the type of pill and whether or not it is covered by insurance. This price typically does not include the cost of the doctor’s examination required to get a prescription for birth control pills. Health clinics, such as Planned Parenthood, may provide their services at lower prices (or even free of charge). For example, the price of one pack of pills can be discounted if you sign up for six months worth of pills. Some clinics are even willing to adjust the price of birth control pills according to one’s annual income and insurance coverage (or lack thereof). Most states in the U.S. allow health clinics to make birth control available to minors for free and without parental consent. As of 2010, the Affordable Care Act allows private health insurance companies to provide birth control without a co-pay. Contact your insurance provider for more information about whether or not your birth control pills are covered by your plan.¹

Common Misconceptions

It is sometimes difficult to distinguish between the facts and many myths surrounding sex and contraception, as this subject is often overlooked or breezed over in health classes. However, it is important to clear up this confusion in order to use contraception safely and effectively and to minimize the risk of unwanted pregnancy.

Here are some common misconceptions to be aware of:

  1. You can’t get pregnant immediately after starting the birth control pill.

False. The time it takes for the birth control pills to be effective varies, but usually it takes at least one week. The hormones in the pill take time to work with the woman’s body to prevent ovulation.?

  1. You can’t get pregnant if you shower, douche, or urinate right after sex.

False. None of these actions will prevent sperm that has already passed through the female’s cervix from entering the uterus.?

  1. You can’t get pregnant if you are not in your “fertile week.”

False. The menstrual cycle tends to follow a regular pattern, but fluctuations in hormone levels due to a variety of factors like stress, age, and medicine, can disrupt the cycle.? Pinpointing ovulation and fertility each month can be challenging, and therefore the rhythm method of contraception is not very effective as a form of birth control.

  1. You can’t get pregnant if it’s your first time having sex.

False. Pregnancy is possible any time ovulation occurs.?  

  1. You can’t get pregnant if you’re on top or standing up during sex.

False. Gravity is not capable of keeping sperm from traveling up the cervical canal after the male partner ejaculates, regardless of the coitus position?  

  1. You can’t get pregnant if you don’t have an orgasm during sex.

False. Pregnancy occurs whenever sperm fertilizes the female’s egg. An egg is released each month by the menstrual cycle, and this will occur whether or not the female has an orgasm?  

  1. You can’t get pregnant if your partner pulls out before ejaculation.

False. Pre-cum, which contains a small amount of sperm, is released from the penis during arousal prior to ejaculation. Although unlikely, the sperm found in pre-cum can sometimes result in pregnancy. The withdrawal method is most effective when paired with a barrier method, like a condom.

What if I Want to Get Pregnant? 

A character with their finger on their chin and questions marks around their hand.

Because birth control pills have no effect on fertility, you can become pregnant immediately after you stop taking the pill (though your cycles may not be regular for a few months). With combination pills, fertility typically returns to normal within two weeks of stopping the pill, and progestin-only pills allow you to get pregnant in even less time.? Despite the fact that it is safe to become pregnant right away, it may be wise to wait until your cycles are regular (this may take up to 6 months) because this will allow your physician to more easily estimate the due date of the baby.?

Concluding Remarks

Birth control pills are oral contraceptives that prevent pregnancy when used correctly. There are two main types of birth control pills (combination and progestin-only) that have differing side effects and usages. These two main types of birth control pills also have specific advantages and disadvantages that should be considered when deciding which type of birth control pill is more ideal. For similarly effective hormonal birth controls that do require the diligence of consuming a daily pill, check out the birth control implant and the types of IUDs available. In the future, male birth control may be available as well– learn more about this topic here.

For more information regarding various types of contraception, consult our Birth Control Comparison Chart and check out the video below!


  1. Planned Parenthood. “Birth Control Pills.” Birth Control Pills – Birth Control Pill – The Pill. Planned Parenthood, 2019.
  2. National Institutes of Health. “Estrogen and Progestin (Oral Contraceptives): MedlinePlus Drug Information.” MedlinePlus, U.S. National Library of Medicine, 2015.
  3. Mayo Clinic Staff. “Minipill.” Mayo Clinic. Mayo Clinic, 2016.
  4. Ruby, Prjkt. “Estrogen Vs. Non-Estrogen Birth Control Pills – What’s the Difference?” PRJKT RUBY, UpScript IP Holdings, LLC , 12 Nov. 2015.
  5. Mayo Clinic Staff. “Combination Birth Control Pills.” Mayo Clinic. Mayo Clinic, 2016.
  6. Cleveland Clinic. “Contraception Myths.” Women’s Health Institute at Cleveland Clinic. Cleveland Clinic, 2019.

Last Updated: May 10, 2019