For most people, birth control is not dangerous. The serious risks are real but rare, and for the majority of users, the benefits outweigh the harms. That said, “birth control” covers a wide range of methods, from hormone-free copper IUDs to combined estrogen-progestin pills, and each carries its own risk profile. Your personal health history, age, and habits like smoking can shift the equation significantly.
Blood Clots: The Most Talked-About Risk
Combined hormonal contraceptives (the pill, patch, and ring that contain both estrogen and a progestin) increase the risk of blood clots in veins, a condition called venous thromboembolism. This is the risk you’ve probably heard the most about, and it’s worth putting into perspective with actual numbers.
Among women not using any hormonal contraception, blood clots occur in roughly 2 out of every 10,000 women per year. Combined pills raise that to about 5 to 12 per 10,000 women per year, depending on the specific formulation. Pills containing older progestins like levonorgestrel sit at the lower end (5 to 7 per 10,000), while newer formulations with drospirenone or desogestrel carry slightly higher rates (9 to 12 per 10,000).
Here’s the comparison that often gets left out: pregnancy itself raises clot risk to about 20 per 10,000 women per year. So while the pill does increase clot risk compared to not taking it, being pregnant is roughly two to four times riskier in that specific regard.
Stroke, Heart Attack, and Smoking
Combined contraceptives also raise the risk of arterial events like stroke and heart attack. A large nationwide study published in The BMJ found that the rate of ischemic stroke was about 18 per 100,000 person-years among non-users, compared to 39 per 100,000 for combined pill users. For heart attacks, the rate went from 8 per 100,000 in non-users to 18 per 100,000 in combined pill users. These are still small absolute numbers for young, healthy women.
The picture changes dramatically if you smoke. Among smokers under 35 on the pill, cardiovascular death is estimated at about 1 per 100,000 users annually. Over age 35, that jumps tenfold to about 1 per 10,000 users annually. The combination of smoking and combined contraceptives after age 35 is one of the clearest danger zones in contraception, which is why most providers will not prescribe combined methods to smokers in that age group.
Who Should Avoid Combined Hormonal Methods
The CDC classifies certain health conditions as making combined hormonal contraceptives an unacceptable risk. These include:
- Migraine with aura at any age
- Uncontrolled high blood pressure (systolic 160 or above, diastolic 100 or above)
- History of stroke or heart disease
- Blood clotting disorders like Factor V Leiden or antiphospholipid syndrome
- Systemic lupus erythematosus
If you have any of these conditions, progestin-only methods or non-hormonal options are typically safer alternatives. A progestin-only pill, for instance, carries much lower cardiovascular risk. In the same BMJ study, stroke rates with progestin-only pills were 33 per 100,000, compared to 39 for combined pills, and heart attack rates were 13 versus 18.
Cancer: Risk Goes Both Ways
Oral contraceptives affect cancer risk in a more complex way than most people realize. They modestly increase the risk of some cancers while significantly lowering the risk of others.
On the risk side, women currently using combined pills have about a 20% to 24% higher risk of breast cancer than non-users. The increase varies by formulation, ranging from 0% to 60% for specific types, and risk climbs with longer use. The reassuring finding is that this elevated risk fades after stopping, and no increased risk is detectable 10 years after discontinuation.
Cervical cancer risk also rises with long-term use. Less than five years of use is associated with about a 10% increase, five to nine years with a 60% increase, and 10 or more years with roughly double the risk. Like breast cancer, this risk declines after stopping the pill.
On the protective side, oral contraceptives reduce the risk of ovarian, endometrial, and colorectal cancers. The protection against ovarian cancer is particularly noteworthy because ovarian cancer is harder to detect early and more often fatal. These protective effects persist for years after stopping.
Mood Changes and Depression
Changes in mood are one of the most common reasons people stop taking the pill, and the evidence increasingly supports that this isn’t just anecdotal. A large Danish study of more than one million women found that hormonal contraceptive users had a higher rate of first-time antidepressant use and first depression diagnoses, with adolescents at the highest risk. Progestin-only methods appear to carry a greater tendency toward depressive symptoms in women who are already vulnerable to mood disorders.
A study on the hormonal IUD similarly found a positive association with depression, anxiety, and sleep problems in women who didn’t have those issues before insertion. Not everyone experiences mood effects, and many people feel fine or even better on hormonal contraception. But if you notice a clear shift in your mental health after starting a new method, the timing is worth paying attention to.
Injectable Contraception and Bone Density
The contraceptive injection (given every three months) carries a unique concern: bone density loss. The FDA’s warning states that prolonged use may cause significant loss of bone mineral density, that the loss increases the longer you use it, and that it may not fully reverse after stopping. The warning specifically flags uncertainty about whether use during adolescence could reduce peak bone mass and raise fracture risk later in life.
That said, professional guidelines from the American College of Obstetricians and Gynecologists concluded after reviewing extensive data that bone density concerns should not prevent prescribing the injection or continuing its use beyond two years, particularly when weighed against the risks of unintended pregnancy. They placed no restriction on duration for women aged 18 to 45.
IUDs: Low Risk, Not Zero Risk
IUDs, both copper and hormonal, are among the safest and most effective contraceptive options. The main physical risks are perforation (the device pushing through the uterine wall) and expulsion (the device partially or fully coming out on its own). Over five years, the perforation rate is about 0.55% for copper IUDs and 0.63% for hormonal IUDs. Expulsion rates over five years run around 4.8% for copper and 4.5% for hormonal versions. Perforation is rare and usually identified quickly. Expulsion is more common but not dangerous in itself, though it does leave you unprotected.
The copper IUD has the advantage of being completely hormone-free, which means no clot risk, no mood effects from hormones, and no impact on bone density. The tradeoff is often heavier, crampier periods, particularly in the first few months.
Putting the Risks in Context
The absolute risk of serious complications from birth control is low for most healthy women under 35 who don’t smoke. A blood clot incidence of 5 to 12 per 10,000 per year means that 99.88% to 99.95% of users won’t develop one in a given year. Stroke and heart attack rates, while roughly doubled on combined pills, are still measured in the tens per 100,000.
Risk concentrates in specific groups: smokers over 35, people with clotting disorders, those with uncontrolled hypertension, and people with a history of migraine with aura. If you fall into one of these categories, combined hormonal methods genuinely are dangerous for you, but safer alternatives exist. For everyone else, the risks are real but small, and for many users, the cancer-protective effects, reliable pregnancy prevention, and other benefits tip the balance clearly in favor of use.