Six decades ago, the first birth control pill was approved by the U.S. Food and Drug Administration—and it was far from perfect. Extremely high doses of hormones led to unnecessary and dangerous side effects that scared people away from the contraceptive altogether.
Although pills on the market today contain hormone levels magnitudes lower and are much safer, questions still abound about how they work and their side effects—particularly as the FDA recently approved one version of the pill to be sold without a prescription.
As with any medication, some side effects and risks are to be expected, but experts who spoke to National Geographic say birth control pill benefits far outweigh the risks when used properly, especially when it comes to preventing pregnancy.
“We're still trying to figure out everything that the pill does, and while we know it does affect women, it’s not dangerous,” says Sarah Hill, a research psychologist who studies women’s health and is the author of This Is Your Brain On Birth Control. “It's about making decisions that are right for you given your specific goals.”
Here’s your guide to the birth control pill.
What are the differences between birth control pills?
There are three types of birth control pills. They all work by releasing synthetic hormones that prevent ovaries from releasing an egg and thickening cervical mucus to block sperm from reaching the uterus.
The combination pill, also called “the pill,” is most commonly prescribed and it contains synthetic versions of the hormones estrogen (ethinyl estradiol), which controls menstrual bleeding, and progesterone (progestin), which prevents pregnancy.
The progestin-only pill, sometimes called the “mini pill,” contains only progestin. The FDA approved an over-the-counter version of this pill on July 13.
The continuous-use pill is a type of combination pill that includes more active pills per pack that could shorten your period, make it less frequent, or completely stop it. (Inactive pills, also known as placebo pills, don’t contain hormones. These induce your period.)
Most birth control pills contain the same type of estrogen. But there are several kinds of progestin used in pills that differ in terms of how they bind to active receptors on your cells, says Stephanie Teal, chair of the OB-GYN department at University Hospitals Cleveland Medical Center in Ohio.
This could explain why one type of pill may give you acne while another might clear it, Teal says.
Generic pills have the same active ingredients as brand name pills, which means they carry the same risks and benefits.
Besides preventing pregnancy, how might the pill help me?
The combination pill specifically can make your period more regular, as well as prevent acne, bone thinning, cysts in your breasts, endometriosis symptoms, anemia, intense mood swings, and certain kinds of cancers (more on this later.)
Synthetic hormones in the pills help balance natural hormonal fluctuations in your body that are responsible for many symptoms like acne and painful cramps.
Will the pill make me moody?
It depends, Hill says.
Mood changes are one of the most common side effects reported among pill takers, according to surveys. Depressive symptoms and increased risks of suicide, particularly among teens ages 15 to 19, are often associated with hormonal contraceptives.
It’s believed that progestin stimulates receptors in the brain for the stress hormone cortisol, Hill says, which is why some people may feel anxious or depressed.
At the same time, other people may use the pill to treat premenstrual dysphoric disorder—severe irritability, depression, or anxiety in the weeks leading up to your period. This works by regulating your hormone levels.
That said, we all respond to hormonal changes differently, Hill says.
Will I gain weight on the pill?
Studies have not found that the pill leads to significant weight gain. (The ring, patch, and intrauterine devices also aren’t associated with weight gain.)
Studies of people who took the progestin-only pill found that they gained an average of about four pounds after six or 12 months on the medication, which was about the same as those using other birth control methods; researchers concluded that people may gain weight naturally over time regardless of contraceptive use.
It’s tricky to blame the pill for weight gain because many factors like diet and stress can contribute.
“On the whole, we don't see a change in weight other than what we would expect somebody to gain just by aging,” says Jennifer Kaiser, an OB-GYN and assistant professor of complex family planning at the University of Utah ASCENT Center for Reproductive Health. She adds that if you do experience weight gain, you can work with your doctor to adjust your dose or change birth control methods.
Does the pill increase my chances of developing blood clots?
About 1 in 3,000 women taking the pill will develop a blood clot, according to the National Blood Clot Alliance. Although this is one of the most significant risks associated with the pill, it’s still extremely rare, experts say.
This risk applies to any birth control method involving estrogen because the hormone encourages the liver to produce more substances that can form clots, Kaiser says. This means progestin-only pills don’t carry blood clot risks.
Meanwhile, pregnancy, which introduces a lot more estrogen in the body, carries a significantly higher clot risk, says Teal: People on the pill have about double the risk of getting a blood clot compared to those not on the pill. Pregnancy increases this risk 5- to 20-fold, Teal says, depending on their age, weight, and smoking status. In the first six weeks postpartum, it goes up 40- to 65-fold.
That’s what researchers call the relative risk, meaning the risk you get a clot while on the pill compared to your risk off of the pill. When it comes to absolute risk, which is the probability you actually develop a clot while on the pill, the odds are “incredibly low,” Teal says.
Can the pill increase my risk of developing breast cancer?
Studies are conflicting, but some show that people who are currently using or recently used any hormonal birth control pill have about a 25 percent greater risk of developing breast cancer compared with non-users. Some data suggest this risk increases the longer you take the pill.
This risk declines when you stop taking it, and disappears completely after about 10 years.
Estrogen and progesterone stimulate the development and growth of some cancers. Because the pill contains synthetic versions of these hormones, it’s assumed that it might fuel cancer growth in people who already have mutations in their breast tissue cells, says Heather Eliassen, professor of epidemiology at the Harvard T.H. Chan School of Public Health who studies breast cancer as director of the Nurses’ Health Study II.
However, absolute risk is far lower, Eliassen says. That’s because most people taking the pill are young and relatively healthy. As we age, breast cancer risk naturally increases.
People who have the BRCA1 and BRCA2 genes that increase their risk of breast cancer may be more likely to develop the disease while on the pill compared to those without the genes. But Kaiser thinks this magnified effect is “pretty minimal” when considering that these genes also increase risks for ovarian cancer, which the pill has been found to protect against.
Can the pill protect me from other cancers?
Yes. Research shows people who have ever used the pill have a 30 to 50 percent lower risk of ovarian cancer than those who have never used it.
Studies have also found that the pill can lower your risk of endometrial cancer by at least 30 percent and colorectal cancer by 15 to 20 percent, according to the National Cancer Institute.
Does the pill lower libido?
There’s no solid evidence that suggests it does overall, but studies have found that anywhere between 5 percent and 48 percent of people on the pill report a drop in sexual desire.
This would make sense, Hill says, because the pill lowers testosterone levels, a hormone that promotes libido in women.
Is it safe to smoke cigarettes while on the pill?
Smoking while on the pill can raise your risk for blood clots and high blood pressure—both of which are risk factors for heart attack and stroke—especially if you’re age 35 or older.
Studies show that increased estrogen levels from the pill are associated with faster nicotine metabolism, which leads to greater dependence, cravings, and withdrawal symptoms.
Generally, if you smoke 15 or more cigarettes a day, don’t use the pill or other birth control methods that involve estrogen like the patch and ring, according to Planned Parenthood. If you smoke or vape nicotine at all, talk with your doctor about what birth control method is safe for you.
It’s safe to use progestin-only pills or other non-estrogen methods like the shot, implant, and IUD.
Can the pill make it harder for me to get pregnant?
No. You can get pregnant immediately after you stop taking the pill, no matter how long you’ve been on it.
In fact, you’re highly likely to get pregnant the month after you get off the pill because your hormones experience a “rebound effect,” Teal says, making you more fertile than usual. The pill may also protect you from pelvic inflammatory disease, an infection of the reproductive organs that can lead to infertility.
However, fertility naturally declines with age, Kaiser warns. So if you started taking the pill at age 18 and you now want to get pregnant at 36, your baseline fertility is going to be different, Kaiser says, “not because of the pill but because you’re older.”
Should I be worried about long-term risks from the pill?
Absolutely not, Hill says. There’s no evidence that the pill causes permanent changes in the body.
Side effects are normal, common, and temporary. About two to three months after starting the pill, your body will have adjusted to the hormonal changes and any uncomfortable symptoms should go away.
Am I better off not taking the pill?
Only you know what’s best for you and your health at any given time. You may want to avoid certain types of pills if you’ve had conditions like uncontrolled hypertension, a blood-clotting disorder, severe diabetes, stroke, or lupus.
When it comes to health risks, however, there’s no denying the fact that pregnancy is the most serious of them all, experts say. Pregnancy complications include depression, heart conditions, diabetes, anemia, infection, and death. Meanwhile, maternal mortality rates are rising in the U.S., standing at 32.9 deaths per 100,000 live births in 2021 compared to a rate of 23.8 in 2020, and 20.1 in 2019.
“We talk a lot about risks with birth control because people feel like they’re opting to take something that they don't necessarily have to,” says Kristyn Brandi, an OB-GYN and complex family planning specialist who’s the American College of Obstetricians and Gynecologists Darney-Landy Fellow.
“But at the same time,” Brandi says, “being pregnant is always more dangerous than not being pregnant.”