Yes, birth control pills can cause blood clots, but the actual risk is far lower than most headlines suggest. Women taking combined oral contraceptives develop venous thromboembolism at a rate of roughly 3 to 9 per 10,000 per year, compared to 1 to 5 per 10,000 among women not on the pill. That translates to an absolute risk of about 0.3% to 1% over a full decade of use. To put that in perspective, the risk of blood clots during pregnancy and the postpartum period is significantly higher, at approximately 1 to 2 per 1,000.
So while the pill does raise clot risk by roughly three- to six-fold in relative terms, the baseline is so low that the overwhelming majority of women will never experience this complication. That said, not all pills carry the same risk, and certain women face compounding dangers that deserve serious attention. A 2025 study reported by Medscape confirmed that hormonal contraceptives elevate blood clot risk approximately threefold, but also found that the risk largely dissipates within two to four weeks of stopping the contraceptive. The first six to twelve months of use represent the highest-risk window. This article breaks down which types of birth control carry the most and least risk, what personal factors multiply the danger, how to recognize warning signs, and what safer alternatives exist for women who cannot tolerate estrogen.
Table of Contents
- How Do Birth Control Pills Actually Cause Blood Clots?
- Which Types of Birth Control Pills Carry the Highest and Lowest Clot Risk?
- Who Is Most at Risk for Blood Clots on the Pill?
- What to Do If You Are Currently on the Pill and Worried About Clots
- Warning Signs of a Blood Clot You Should Never Ignore
- The First Year on the Pill Is the Riskiest Window
- How Clot Risk Fits Into the Broader Picture of Hormonal Health
- Conclusion
- Frequently Asked Questions
How Do Birth Control Pills Actually Cause Blood Clots?
Estrogen is the primary driver of clot risk in hormonal contraceptives. It increases the levels of clotting factors — specific proteins in the blood that promote coagulation. Under normal circumstances, the body maintains a careful balance between clotting and anti-clotting mechanisms. Estrogen tips that balance toward clotting. This is also why pregnancy itself carries a higher clot risk: estrogen levels surge naturally during pregnancy, and the body ramps up clotting capacity in preparation for delivery.
Not all delivery methods are equal, either. The birth control patch delivers roughly 60% more estrogen absorption than oral pills, which makes it a higher-risk option than many women realize. The vaginal ring is associated with a 6.5-times higher clot risk compared to non-users, which is notably higher than the pill itself. These differences matter because a woman might switch from the pill to the ring thinking she is making a neutral change, when she may actually be increasing her exposure. Understanding that estrogen dose and delivery method both shape risk is essential for making an informed choice.
Which Types of Birth Control Pills Carry the Highest and Lowest Clot Risk?
The generation of progestin in a combined pill meaningfully affects thrombotic risk, and this is something many prescribers gloss over. Second-generation pills containing levonorgestrel or norgestrel carry the lowest thrombotic risk among combined oral contraceptives. These are older formulations, widely available as generics, and remain a solid first-line option for women who want a combined pill with the smallest clot footprint. Third-generation pills containing desogestrel, gestodene, or norgestimate carry a higher relative risk than their second-generation predecessors, despite being marketed as newer and sometimes implied to be better. Drospirenone-containing pills such as Yaz and Yasmin deserve particular mention.
The FDA added a specific warning about these formulations because they carry an estimated three- to four-fold increased clot risk compared to non-users. Some women are prescribed these pills for acne or premenstrual symptoms without a full discussion of the added thrombotic trade-off. However, if a woman has already been on a drospirenone pill for more than a year without issues, her risk has likely dropped from the initial peak period. The decision to switch should weigh the proven tolerance against the risks of the current formulation. Progestin-only methods, including the mini-pill and hormonal IUDs, have little to no increased clot risk because they lack estrogen entirely. Non-hormonal copper IUDs have no effect on clot risk whatsoever. For women with known clotting disorders or multiple risk factors, these options represent the safest contraceptive choices from a vascular standpoint.
Who Is Most at Risk for Blood Clots on the Pill?
Certain women face a dramatically amplified danger when combining hormonal contraceptives with preexisting risk factors. Inherited thrombophilias — genetic conditions like Factor V Leiden or prothrombin gene mutation — are the most concerning. A woman with Factor V Leiden who takes combined oral contraceptives may face a clot risk that is dozens of times higher than a woman without the mutation who is not on the pill. The compounding effect is multiplicative, not merely additive. Most women do not know they carry these mutations because they are typically asymptomatic until a clot event occurs. Obesity independently raises clot risk and compounds further with birth control use. Smoking, particularly in women over 35, is another well-established multiplier — this is why most prescribers will not provide combined hormonal contraceptives to smokers in that age group.
Age itself raises the baseline risk. A 40-year-old woman on the pill faces a higher absolute risk than a 20-year-old on the same formulation, even if neither smokes or has other risk factors. Immobility from long flights, surgery, or hospitalization adds yet another layer. A woman on the pill who undergoes a major surgery and spends days in bed is stacking multiple risk factors simultaneously. Family history of blood clots should prompt a conversation with a hematologist before starting estrogen-containing contraception. The American Society of Hematology published a 2024 education article titled “Estrogen, Progestin, and Beyond: Thrombotic Risk and Contraceptive Choices,” reviewing how different hormonal formulations affect clotting risk across patient populations. Doctors broadly recommend that women with known clotting disorders avoid estrogen-containing contraceptives and opt for progestin-only or non-hormonal alternatives instead.
What to Do If You Are Currently on the Pill and Worried About Clots
The first step is an honest risk assessment, not panic. For a healthy, non-smoking woman under 35 with no personal or family history of blood clots, the absolute risk on combined oral contraceptives remains low. The American Society for Reproductive Medicine noted in its 2016 guideline that the absolute risk remains small for most healthy young women. Stopping the pill abruptly out of fear may introduce other risks, including unintended pregnancy, which carries its own — and statistically higher — clot risk. If you do have risk factors, the conversation with your prescriber should focus on alternatives.
Switching from a combined pill to a progestin-only mini-pill eliminates the estrogen-driven clot risk almost entirely. A hormonal IUD like the levonorgestrel-releasing type delivers progestin locally with minimal systemic absorption, making it one of the safest hormonal options for women concerned about clotting. A copper IUD removes hormones from the equation altogether. The trade-off with progestin-only pills is that they require stricter timing discipline — taking the pill at the same time each day — and may cause irregular bleeding. The trade-off with the copper IUD is heavier menstrual periods for some women. Each option has its costs, and the right choice depends on what a woman is willing to manage.
Warning Signs of a Blood Clot You Should Never Ignore
The two most dangerous clot-related emergencies are deep vein thrombosis and pulmonary embolism. DVT typically presents as swelling, pain, warmth, or redness in one leg — usually the calf or thigh. It often affects only one side, which helps distinguish it from general muscle soreness or fluid retention. Pulmonary embolism, which occurs when a clot breaks free and travels to the lungs, causes sudden shortness of breath, chest pain that may worsen with deep breathing, rapid heartbeat, and sometimes coughing up blood. Both are medical emergencies.
A limitation worth noting: many women experience leg cramps, minor swelling, or occasional shortness of breath that have nothing to do with blood clots. Anxiety about clot risk can itself produce symptoms like chest tightness and rapid breathing. The distinguishing features of a real DVT are that the swelling is typically in one leg, it worsens over hours rather than minutes, and it does not resolve with stretching or rest. If there is genuine uncertainty, an urgent care visit or emergency department evaluation with a D-dimer blood test and ultrasound can rule out a clot quickly. The risk of ignoring a real clot far outweighs the inconvenience of a negative workup.
The First Year on the Pill Is the Riskiest Window
The 2025 study data confirmed what earlier research had shown: the highest risk period for blood clots on hormonal contraceptives is during the first six to twelve months of use. This is when the body is adjusting to the new hormonal environment, and clotting factor levels are shifting.
A woman who has been on the same combined pill for five years without incident is at substantially lower risk than a woman who just started last month. This timing matters practically — if a woman stops the pill and restarts it a year later, she re-enters that high-risk initial window. Cycling on and off combined contraceptives repeatedly may actually be riskier than staying on them continuously, a nuance that is rarely discussed.
How Clot Risk Fits Into the Broader Picture of Hormonal Health
Research into hormonal contraceptives and vascular risk continues to evolve. The reassuring finding from the 2025 Medscape-reported study is that clot risk largely dissipates within two to four weeks of stopping hormonal contraceptives, meaning the effect is not permanent and does not leave lasting vascular damage for most women.
Looking ahead, pharmaceutical development is exploring contraceptive formulations with lower estrogen doses or novel progestins that may further reduce thrombotic risk while preserving contraceptive efficacy. For now, the existing evidence supports a personalized approach: assess individual risk factors, choose the lowest-risk formulation that meets a woman’s needs, and maintain awareness of warning signs without succumbing to disproportionate fear.
Conclusion
Birth control pills do increase the risk of blood clots, primarily through their estrogen content. The relative risk rises three- to six-fold, but the absolute risk remains low for most healthy young women — roughly 3 to 9 per 10,000 per year, compared to the substantially higher risk during pregnancy and postpartum. The type of pill matters: second-generation levonorgestrel-based formulations carry the lowest risk among combined pills, while drospirenone-containing pills like Yaz and Yasmin carry additional risk. Progestin-only and non-hormonal methods are the safest options for women with clotting concerns.
The practical takeaway is straightforward. Know your personal and family history regarding blood clots. If you have risk factors — thrombophilia, obesity, smoking, age over 35, or a history of clots — talk to your doctor about estrogen-free alternatives. If you are on a combined pill and doing well with no risk factors, the evidence does not support switching out of generalized anxiety. Watch for warning signs, especially during the first year of use, and seek immediate medical attention for unexplained leg swelling or sudden chest pain and shortness of breath.
Frequently Asked Questions
Can I get a blood clot from any birth control pill?
Combined pills containing both estrogen and progestin carry increased clot risk. Progestin-only pills (the mini-pill) have little to no increased risk because they lack estrogen, which is the primary driver of clotting factor changes.
Is the birth control patch or ring safer than the pill for blood clots?
No. The patch delivers roughly 60% more estrogen than pills, and the vaginal ring is associated with a 6.5-times higher clot risk compared to non-users. Both carry equal or greater risk than most oral combined contraceptives.
How quickly does clot risk go away after stopping the pill?
A 2025 study found that the elevated risk largely dissipates within two to four weeks of discontinuing hormonal contraceptives. The effect does not appear to cause lasting vascular changes.
Should I get tested for clotting disorders before starting birth control?
Routine screening is not currently recommended for all women, but if you have a family history of blood clots, DVT, pulmonary embolism, or known thrombophilia in a close relative, testing before starting estrogen-containing contraception is a reasonable step to discuss with your doctor.
Is it safer to stay on the pill long-term or take breaks?
Counterintuitively, staying on the pill continuously may be safer than cycling on and off. The highest risk period is the first 6 to 12 months of use, and each time you restart after a break, you re-enter that elevated-risk window.
Are blood clots from birth control fatal?
They can be. Pulmonary embolism, which occurs when a clot travels to the lungs, is a life-threatening emergency. However, with prompt medical treatment, most clot events are survivable. The key is recognizing symptoms — leg swelling, sudden shortness of breath, chest pain — and seeking immediate care.
