Oral contraception is available as a pill containing hormones. There are pills with both estrogen and a progestin (“the pill” or “the combined pill”), and pills with only progestin (“the mini-pill”).
This article is part of our Contraception Series!
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Note: the information below was sourced from references (1-5), unless stated otherwise.
What is it?
Oral contraception is available as a pill containing hormones. There are pills with both estrogen and a progestin (“the pill” or “the combined pill”), and pills with only progestin (“the mini-pill”). What these hormones do is explained in more detail below, but they essentially "trick" the body into thinking it's already pregnant.
The pills come in strips, typically containing enough pills for one whole month. Whichever type of pill you choose, you take one of them each day, at the same time every day.
You can take the combined pill on different schedules. Usually, you take it for three weeks uninterrupted, and then you take a week off. This allows menstruation to happen during that week. Afterwards, you start a new strip.
Some strips come with three weeks of hormone-containing pills and one week of sugar pills (placebo pills) that don’t contain any hormones, so you stay in the habit of taking a pill each day. Other strips only contain the three weeks of hormone-containing pills. Some people prefer these strips because it allows them to skip the hormone-free week (and, as a result, to skip menstruation). In that case, you would move on to a new strip immediately without taking a week off. This is called “extended-cycle contraception”.
When you’re taking the mini-pill, each pill in your strip contains hormones. You don’t take a hormone-free week.
Which type of pill you can get and what schedule your doctor recommends for you, depends on your medical history, your personal circumstances, and what’s available in your area.
Before your doctor prescribes combined oral contraception to you, they will usually measure your blood pressure. This is not typically necessary if you’ve chosen progestin-only pills.
How does it work?
The combined pill contains both estrogen and progestin. The min-pill contains only progestin. Estrogen is a hormone found naturally in the body, and progestin is a synthetic version of the natural hormone progesterone. These pills work because the hormones in them suppress ovulation, preventing the release of an egg. If there’s no egg, fertilization can’t take place. This is mainly an effect of estrogen, which means that mini-pills often won’t suppress ovulation. However, both types of pills also thicken the mucus in the cervix, which prevents sperm cells from going through the cervix into the uterus. This prevents fertilization of an egg if one did get released. Lastly, the hormones in the pills make the endometrium thinner, which prevents implantation of any egg that did get fertilized.
How effective is it?
Contraceptive pills are very effective. With perfect use, they are 99.7% effective in protecting against pregnancy (meaning out of 1000 people* using this method, about 3 people* become pregnant in a year).
With typical use, effectivity decreases to 91% (leading to 90 pregnancies per 1000 people* per year). This large difference is because it’s very important to take your pill every single day, and preferably around the same time each day. That goes especially for the mini-pill, because a pill taken as little as three hours late is considered missed (compared to 24 hours for the combined pill). Keeping such a tight schedule is difficult for many people, for example because of unpredictable working hours. If you think this might be difficult for you too, a different form of (hormonal) contraception may be more suitable for you, for example an injection, patch, or IUD.
Certain medications can reduce the effectivity of contraceptive pills, including medication for seizures and certain antibiotics. Ask your doctor about any interactions with drugs and supplements you’re taking, because this might increase your risk of pregnancy.
What are possible side-effects?
The combined pill and the mini-pill have slightly different side-effects. This is because the combined pill contains two types of hormones while the mini-pill has only one. We go into the side effects of both pills separately below.
Many people experience irregular spotting or bleeding in the first three to six months of use. This is especially common if you’re taking hormone-containing pills continuously, without a hormone-free week (the week in which you don't take any pills at all, or you take the sugar pills that come in the packet). Most people will also have less pain during menstruation. Acne might be improved, but it can also worsen. Some people experience headache, breast tenderness, weight gain, and mood changes. Your risk of thrombosis is increased with use of the contraceptive pill – especially if you smoke - which can lead to a stroke, a heart attack, and more (though these risks are much lower than during pregnancy). Some people experience an increase in pigmentation of the skin of the face, called melasma.
Contraceptive pills also reduce the risk of endometrial and ovarian cancer.
Some of these side-effects seem very dangerous, but they are very rare. Getting good counselling before starting on these birth control methods is important to minimize your risk of any of these effects. Compared to pregnancy or childbirth, oral contraceptives are incredibly safe: a young, healthy, non-smoking female using her oral contraceptives for one year has a one-in-a-million chance of dying due to side effects from this contraception (3). The mortality rate of mothers and pregnant people as a result of pregnancy or childbirth was about 211 deaths per 100,000 live births globally in 2017 (6), and about 3 deaths per 100,000 live births in the United States (3) – though this number is higher for certain groups, especially for Black women. For most people, the chance of dying during pregnancy or childbirth is therefore much larger than their chance of dying from side-effects related to oral contraception.
Changes in bleeding patterns are common: you might experience irregular spotting and bleeding may become lighter overall. Some people experience headaches, dizziness, or nausea. Others might gain weight, experience mood changes, or have tenderness in their breasts.
Note that only a portion of people experience (some of) these side-effects, and some people will experience side-effects not listed here. Whether you will, depends on many different factors.
When can't I use it?
The restrictions for using the combined pill are slightly different from the mini-pill. We list these restrictions for both types of pills separately below.
You can't take the pill during the first three to six weeks after delivery of a child. You also sometimes can’t use this contraception if you’re a smoker, if you’ve had bariatric surgery (such as a gastric bypass), or if you have high blood pressure (hypertension), certain rheumatic diseases, migraines with aura, multiple sclerosis, diabetes (of more than 20 years), inflammatory bowel disease (such as Crohn’s disease or ulcerative colitis), liver disease, gallbladder disease, cardiovascular (heart and vessel) disease, stroke, thrombosis or risk factors for thrombosis, or breast cancer.
If you’re breastfeeding, you might also not be able to take the combined pill. This is because evidence suggests the pill has a negative impact on milk production. People taking the combined pill typically breastfeed for a shorter period of time as a result of this. Pills with higher doses of hormones might also lead to the development of excess breast tissue in your child (7). Discuss with your doctor whether these issues also apply to you and your prescription.
You often can't take the pill if you’ve had bariatric surgery (such as a gastric bypass), if you have or have had a stroke or heart disease, if you have certain rheumatic diseases, if you have unexplained bleeding from your genitals, if you have or have had breast cancer, if you have liver disease or a liver tumor, or if you’re taking certain medications (such as specific anti-seizure medication or specific antibiotics).
The mini-pill is often given to people when they’re breastfeeding, because there is no evidence this pill affects the breastfeeding process or has effects on your child.
Sometimes, you can take the pill or mini-pill even if you have one of these things. Talk to your doctor to find out if your health issue would definitely mean you can’t take the pill or mini-pill.
Does it work immediately?
This depends on when you’re starting the pills. If you start within five days of starting your menstruation, you’re protected immediately. If you start after more than five days since starting your menstruation, you need to use another method of contraception (for example, a condom) if you’re having sex in the seven days (two days for the mini pill) following your first pill. You also need to do this if you’re more than three weeks postpartum and aren’t breastfeeding. Check with your doctor which situation applies to you if you’re not sure.
If you miss any of your pills (meaning you’re more than 24 hours late for the combined pill or more than 3 hours for the mini-pill), contact your health care provider if you’re unsure what to do. The same applies to when you’ve been vomiting or when you’ve had severe diarrhea. The insert in your pill packet will usually describe in which cases you’re still protected and in which cases you aren’t, but some situations are quite complicated. If it’s not entirely clear to you, it’s better to check with your doctor to minimize your risk of pregnancy.
What happens to my fertility if I stop using it?
Fertility typically returns in a couple of weeks to three months after you stop using the pill or mini-pill (8, 9).
Does it protect against sexually transmitted diseases (STDs)?
No. Hormones alone do not protect against STDs. If you’re having sex with someone new or untested, use a barrier method as well.
*People, here, means anyone who is able to become pregnant, including girls, women, and non-binary people and transgender men who still have their uterus, vagina, and ovaries.
Are you curious about other methods to protect yourself from an unwanted pregnancy? Read about other birth control options here!
This article is pending medical review.
Written by Juliëtte Gossens
Reviewed by Sophie Oppelt and Selina Voßen
Edited by Juliëtte Gossens
McFarlane I (ed.). Seeing the unseen: The case for action in the neglected crisis of unintended pregnancy. United Nations Population Fund. 2022. Available from: https://www.unfpa.org/sites/default/files/pub-pdf/EN_SWP22%20report_0.pdf
Hacker NF, Gambone JC, Hobel CJ (eds.). Hacker & Moore’s Essentials of Obstetrics & Gynecology. 6th ed. Philadelphia: Elsevier; 2016.
Hoffman BL, Schorge JO, Halvorson LM, Hamid CA, Corton MM, Schaffer JI (eds.). William’s Gynecology. 4th ed. New York: McGraw-Hill Education; 2020.
Centers for Disease Control and Prevention. The United States Medical Eligibility Criteria for Contraceptive Use, 2016 (US MEC). Available from: https://www.cdc.gov/reproductivehealth/contraception/mmwr/mec/summary.html
Centers for Disease Control and Prevention. 2016 U.S. Selected Practice Recommendations for Contraceptive Use (U.S. SPR). Available from: https://www.cdc.gov/reproductivehealth/contraception/mmwr/spr/summary.html
UNICEF. Maternal mortality. Available from: https://data.unicef.org/topic/maternal-health/maternal-mortality/ [Accessed September 14th, 2022]
Drugs and Lactation Database (LactMed). Contraceptives, Oral, Combined. Available from: https://www.ncbi.nlm.nih.gov/books/NBK501295/ [Accessed September 21st, 2022]
Girum T, Wasie A. Return of fertility after discontinuation of contraception: a systematic review and meta-analysis. Contraception and Reproductive Medicine. 2018;3:9. DOI: 10.1186/s40834-018-0064-y
Barnhart KT, Schreiber CA. Return to fertility following discontinuation of oral contraceptives. Fertility and Sterility. 2009;91(3):659-663. DOI: 10.1016/j.fertnstert.2009.01.003
Please note: the information we provide to you here is for educational purposes only. If you’re experiencing any discomfort or have any complaints or questions about your health, please contact your doctor or other relevant health professional. We don’t provide medical advice.