The Pill (Combined Oral Contraceptive)
The drug that reshaped women's lives, and what it actually does
Evidence grade 5 of 5, Settled. Read how the Atlas grades evidence.
Contraceptive efficacy of the combined pill is settled science, endorsed by WHO, ACOG, RCOG, NICE and the CDC US MEC and on the WHO Model List of Essential Medicines, with roughly 0.3 percent failure at perfect use and about 9 percent at typical use in US data. The venous-thromboembolism, stroke and cancer risk-benefit profile is characterized by large meta-analyses (Dragoman 2018; Collaborative Group on Hormonal Factors), so grade 5 reflects consensus on effectiveness, not an absence of risk.
Reference only. Not medical advice.
What can go wrong
The combined pill raises the risk of venous blood clots (absolute risk still low, roughly 3 to 9 per 10,000 woman-years versus about 1 to 2 in non-users, and higher with desogestrel, gestodene or drospirenone than with levonorgestrel), and it raises stroke and heart-attack risk in the presence of smoking, older age, high blood pressure, or migraine with aura, for whom it is contraindicated. Leg swelling or pain, chest pain, breathlessness, or a sudden severe or unusual headache while taking it needs urgent medical attention.
This is something to take to a clinician. The Atlas can tell you what is known about the pill (combined oral contraceptive) in general. It cannot tell you what is happening in your body, and the difference matters most for exactly the symptoms that bring people to this page.
Approved in 1960, the combined pill made reliable, woman-controlled contraception possible for the first time, and it works by using hormones to switch off ovulation.
How it works
The combined pill contains estrogen and a progestin. Its main action is to prevent ovulation by suppressing the hormonal signals that release an egg, and it also thickens cervical mucus and thins the uterine lining. No egg released means no pregnancy.
Safety in detail
The combined pill is estrogen-containing and is not suitable for everyone: it should not be used with migraine with aura, active or prior venous thromboembolism, smoking at age 35 or older, uncontrolled hypertension, or certain other conditions, per the CDC US MEC and WHO MEC. It should be started only after a medical history and blood-pressure check, and any diagnosis or new symptom warrants a qualified provider rather than self-management.
What people get wrong
Often saidThe pill just prevents implantation.
ActuallyIts main action is to stop ovulation, so in most cycles no egg is released at all.
Often saidThe pill is dangerous for everyone.
ActuallyFor most healthy women the risks are small and are outweighed by benefits, though it is not right for people with certain risk factors.
Who profits, and who pushes back
Reproductive medicine guidelines
Regard the combined pill as safe and effective for most women when prescribed with a medical history.
Margaret Sanger and Katharine McCormick
Funded and drove the development of an oral contraceptive to give women control over fertility.
Where the research comes from
Most of the published research on this comes from one place. 90% of it is from United States (first approved). Findings that no unrelated group has reproduced are weaker than the study count makes them look.
| Place | Share of published research |
|---|---|
| United States (first approved) | 90% |
| Europe | 88% |
| Global | 84% |
How we got here
Efforts to prevent pregnancy are ancient, but the hormonal pill is a mid-twentieth-century invention. The birth-control campaigner Margaret Sanger set the goal and the philanthropist Katharine McCormick funded it, the biologist Gregory Pincus led the work with the reproductive physiologist Min Chueh (M.C.) Chang, and the Catholic gynecologist John Rock ran the human trials, controversially sited in Puerto Rico. The chemistry came from Mexico, where at the company Syntex the chemist Carl Djerassi and colleagues synthesized the oral progestin norethindrone from Mexican yam (Dioscorea) diosgenin, while Frank Colton at G.D. Searle made the related norethynodrel used in the first pill. Searle's Enovid was approved in the United States for menstrual disorders in 1957 and as a contraceptive on May 9, 1960; the field later shifted to lower estrogen doses and to levonorgestrel and newer progestins as risk data accumulated.
Built in the 1950s from hormone chemistry rooted partly in the Mexican yam, and championed by campaigners who wanted women to control their own fertility, the pill was approved in 1960 and quickly became one of the most consequential medications of the century.
- Ancient worldPlant pessaries and other fertility-control attempts
- 1950sPincus, Rock, and Syntex chemists develop the hormonal pill
- 1960United States approves the combined pill
- 1960s onwardWorldwide adoption reshapes women's lives
How it is understood
The pill gave women reliable control over their fertility that did not depend on a partner, which reshaped education, work, and family life across much of the world. It remains one of the most studied medications in history.
At a glance
- First approved
- United States, 1960
- Main action
- Stops ovulation
- Non-contraceptive benefit
- Lower ovarian and endometrial cancer risk
- Main risk
- Small increased risk of blood clots
What this entry does not yet cover
What follows is unfinished work on our side, not a finding about The Pill (Combined Oral Contraceptive). A short entry is not a safe entry.
- Cost and market. We have not documented what it sells for or who sells it.
- Supply chain. We have not mapped where it is made.
- Who uses it. We have not documented the user groups.
- What could change. No forward-looking summary yet.
- How it compares. We have not set it against the alternatives.
- Children and teenagers. We have not checked what is known about younger people.
- What people take it for. We have not catalogued the claims made for it.
Sources
Absolute VTE incidence is about 6 per 10,000 woman-years on the pill versus about 1 to 2 per 10,000 in non-users, with levonorgestrel lower risk than newer progestins
Risk of venous thromboembolism with oral contraceptives (PMC review)
Meta-analysis quantifying VTE risk across combined oral contraceptive formulations by progestin type
Migraine with aura plus combined hormonal contraception is associated with roughly a 6-fold ischemic-stroke risk; CDC US MEC advises against combined hormonal contraceptives in migraine with aura
CDC, US Medical Eligibility Criteria for Contraceptive Use, and CDC stroke-risk evidence summary
Typical-use failure about 9 percent and perfect-use about 0.3 percent per year for the combined oral contraceptive in the United States
Guttmacher Institute, Contraceptive Effectiveness in the United States
Combined oral contraceptive mechanism, efficacy, contraindications and adverse effects overview
Long-term combined oral contraceptive use is associated with reduced ovarian and endometrial cancer risk that persists for decades, and a small transient rise in breast and cervical cancer risk
Cancer Council Australia, Combined Oral Contraceptives and Cancer Risk position statement
Contraceptive methods including combined oral contraceptives lower risk of ovarian and endometrial cancers
FIGO, protective effect of contraceptive methods against gynaecological cancer
Combined hormonal contraception and VTE risk clinical guidance
Enovid was the first hormonal contraceptive, made by G.D. Searle and FDA-approved for contraception in 1960; roles of Pincus, Chang, Rock, Sanger and McCormick
FDA approved Enovid as an oral contraceptive on May 9, 1960; regulatory history
US Food and Drug Administration, FDA's Approval of the First Oral Contraceptive, Enovid
Mexican scientists and Syntex synthesized the first oral progestin (norethindrone) from Mexican yam diosgenin
The origins of oral contraception: the role of Mexican scientists (ScienceDirect)