For the vast majority of women, birth control is safe. The FDA approves contraceptive products only when they are shown to be both safe and effective, and decades of data on tens of millions of users confirm that serious complications are rare. That said, “safe” isn’t a simple yes or no. The risk profile shifts depending on which method you use, your age, whether you smoke, and a handful of other personal factors. Understanding those specifics is what turns a vague reassurance into something actually useful.
Common Side Effects Most Users Experience
The side effects that affect the most people are also the least dangerous. Combined hormonal pills commonly cause breast tenderness, headaches, nausea, and spotting between periods, especially in the first few months. Unscheduled bleeding occurs in roughly 10 to 18% of combined pill users per cycle and is even more common with progestin-only pills, where about 40% of users report irregular cycles. These effects usually improve after three to six months as your body adjusts to the hormones.
Progestin-only methods like newer pills have shown a progressive reduction in bleeding days over time. In clinical studies, both scheduled and unscheduled bleeding dropped significantly between the fourth and sixth cycle of use. For most women, nuisance side effects are the beginning and end of their experience with birth control risks.
Blood Clots: The Risk in Real Numbers
Blood clots are the most well-known serious risk of combined hormonal contraceptives (those containing both estrogen and a progestin). The reported incidence is about 6 per 10,000 women per year of pill use. To put that in perspective, pregnancy itself carries a blood clot risk roughly three to five times higher than that. The risk is real but small in absolute terms, and it’s concentrated in specific groups: women who smoke, those over 35, people with a family history of clotting disorders, and those who are significantly overweight.
Progestin-only methods tell a different story. Pills that contain only a progestin are not associated with an increased risk of blood clots at all. This makes them a practical alternative for women who have cardiovascular risk factors but still want hormonal contraception. The same applies to hormonal IUDs and implants, which deliver progestin locally or in very low systemic doses.
Stroke Risk and Who Should Avoid Estrogen
Combined oral contraceptives slightly raise the risk of ischemic stroke, with studies showing roughly a twofold increase in relative risk even with today’s low-dose formulations. That sounds alarming, but the baseline risk for young, healthy women is extremely low, so doubling a tiny number still produces a tiny number.
The concern becomes more meaningful when other stroke risk factors stack up. The American College of Obstetricians and Gynecologists recommends that women 35 and older who smoke, and women who experience migraines with aura, use progestin-only or non-hormonal methods instead of combined pills. Diabetes, high blood pressure, obesity, and high cholesterol also shift the calculus. If none of those apply to you, the stroke risk from a combined pill remains very small.
Birth Control and Cancer Risk
Hormonal contraceptives have a complicated relationship with cancer, and the picture includes both increased and decreased risks depending on the type.
On the risk side, a large analysis found that women who had ever used any hormonal contraceptive had about a 24% relative increase in breast cancer risk compared to women who never used one. That increase is modest in absolute terms and appears to grow with longer use, rising from about 11% with less than a year of use to 34% with five to ten years of use. Importantly, data from an older but large pooled analysis of over 150,000 women found that breast cancer risk declined after stopping hormonal contraceptives, with no detectable increase remaining by ten years after stopping.
On the protective side, oral contraceptives significantly reduce the risk of ovarian and endometrial cancers. These protective effects persist for years, sometimes decades, after a woman stops taking the pill. For women with a family history of ovarian cancer in particular, this can be a meaningful benefit.
The Injection and Bone Density
The birth control injection (given every three months) carries a unique concern that other methods do not: bone mineral density loss. The FDA requires a boxed warning stating that users may lose significant bone density, that the loss increases with longer use, and that it may not be completely reversible. The FDA does not recommend using the injection as a long-term method for longer than two years unless other options are considered inadequate.
Studies on recovery paint a mixed picture. In adolescents who used the injection for more than two years, bone density at the hip had not fully recovered five years after stopping. In adults, only partial recovery at the hip, neck of the femur, and lower spine was seen two years after discontinuation. This matters most for teenagers and young adults, who are still building the peak bone mass they’ll carry for the rest of their lives. If you’re considering the injection, it’s worth weighing this against the convenience it offers.
Copper IUD: Hormone-Free but Not Risk-Free
The copper IUD appeals to women who want to avoid hormones entirely, and its safety profile is strong. It contains no hormones, so it carries none of the risks related to blood clots, stroke, or hormonally influenced cancers. The risks that do exist are mechanical. Over five years, the chance of the IUD perforating the uterine wall is about 0.55%, and the chance of the device being expelled (partially or fully pushed out) is roughly 4.8%. Both of these events are most likely to happen in the first few months after insertion. Perforation is uncommon and usually identified quickly, while expulsion simply means the device needs to be replaced.
Fertility After Stopping Birth Control
One of the most persistent worries about birth control is whether it will make it harder to get pregnant later. The evidence is reassuring. A large systematic review found that 83% of women who stopped contraception with the intention of becoming pregnant did so within 12 months, regardless of the method used. Broken down by type, the 12-month pregnancy rate was about 87% for former pill users, 85% for former IUD users, 75% for former implant users, and 78% for former injection users.
The injection shows the longest delay in return to fertility, which makes sense given its slow-release design. But even with that method, the delay is temporary. The review’s conclusion was direct: contraceptive use, regardless of duration or type, does not have a negative effect on the ability to conceive after stopping. There may be a brief delay while residual hormones clear, but it does not cause lasting infertility.
Choosing Based on Your Risk Profile
No single birth control method is universally the safest. The right choice depends on your individual health picture. Combined hormonal methods (pills, patch, ring) are safe for most women but carry small cardiovascular risks that become more significant if you smoke, are over 35, have high blood pressure, or get migraines with aura. Progestin-only pills, hormonal IUDs, and implants avoid the estrogen-related clot and stroke risks entirely while still offering strong pregnancy prevention. The copper IUD eliminates hormonal concerns altogether, with only a small mechanical risk. The injection is highly effective but best suited as a shorter-term option due to its effect on bones.
For a healthy, non-smoking woman under 35 with no major cardiovascular risk factors, virtually every available method falls well within the range of safe. The serious risks, while real, affect a very small number of users and are largely predictable based on factors you and a clinician can identify in advance.