The most effective way to prevent blood clots from birth control is to choose a method that doesn’t contain estrogen. Estrogen is the ingredient that drives clot risk, and several highly effective alternatives exist that skip it entirely. If you prefer or need to stay on a combined pill, patch, or ring, you can still lower your risk by choosing specific formulations, understanding your personal risk factors, and knowing the warning signs.
Why Estrogen Raises Clot Risk
Combined hormonal contraceptives (the pill, patch, and ring) contain both estrogen and a progestin. Estrogen shifts the balance of your blood’s clotting system. It increases the proteins that form clots while reducing the proteins that dissolve them. The net effect is blood that clots more easily than it should.
For women not using any hormonal method, the baseline risk of a blood clot is roughly 2 to 4 per 10,000 women per year. Combined hormonal contraceptives raise that risk about 3.5 times, bringing it to roughly 7 to 14 per 10,000 women per year. For context, pregnancy itself carries an even higher risk: 5 to 20 per 10,000 woman-years. So while the increase from birth control is real, the absolute numbers remain small for most people.
Switch to a Progestin-Only or Non-Hormonal Method
If clot risk is your primary concern, the most straightforward fix is removing estrogen from the equation. Several options carry no measurable increase in clot risk compared to using nothing at all:
- Hormonal IUD (levonorgestrel): No increased clot risk (relative risk 0.6 compared to nonusers). It’s over 99% effective and lasts 3 to 8 years depending on the brand.
- Progestin-only pill (mini-pill): No increased clot risk at low doses (relative risk 0.9 compared to nonusers). Requires taking the pill at the same time each day with no placebo week.
- Copper IUD: Completely hormone-free, 99.2% effective, and lasts up to 10 years. It works by creating a localized inflammatory response that stops sperm from surviving. This is the go-to option for anyone who wants to avoid hormones altogether.
- Implant: The data is more limited, but studies show a relative risk of 1.4 compared to nonusers, and the confidence interval includes the possibility of no increase at all. It’s still a far lower risk than combined methods.
One important exception among progestin-only methods: the injectable shot (depot medroxyprogesterone acetate) does appear to increase clot risk, so it’s not the best choice if clot prevention is your goal.
If You Stay on Combined Birth Control, Pick the Right Progestin
Not all combined pills carry the same level of risk. The type of progestin paired with estrogen matters significantly. Pills containing levonorgestrel (sometimes called “second-generation” progestins) have the lowest clot risk among combined options, with an incidence of about 9 per 100,000 woman-years.
Newer progestins tell a different story. Pills containing drospirenone carry roughly 2.5 to 3 times the clot risk of levonorgestrel pills, with an incidence around 23 per 100,000 woman-years. Pills with desogestrel and gestodene (third-generation progestins) fall in a similar higher-risk range. If you’re going to use a combined method, asking your provider for a levonorgestrel-based pill is one of the simplest risk-reduction steps you can take.
Know Your Personal Risk Factors
Certain characteristics make combined hormonal methods riskier for some people than others. The CDC’s eligibility criteria flag several key factors:
- Smoking and age: If you smoke and are under 35, combined methods are generally still considered acceptable, though not ideal. If you’re 35 or older and smoke fewer than 15 cigarettes a day, combined methods are usually not recommended. If you’re 35 or older and smoke 15 or more cigarettes daily, combined methods should not be used at all due to the risk of heart attack and stroke on top of clot risk.
- Obesity: A higher BMI independently raises clot risk and compounds the effect of estrogen.
- Family history of clots: A parent or sibling who had a blood clot, especially before age 50, is a meaningful signal. Inherited clotting conditions like Factor V Leiden are present in about 5% of people of European descent and can multiply the risk from birth control dramatically.
- Immobility: Recent surgery, a leg cast, or prolonged bed rest all raise clot risk on their own and stack with hormonal risk.
Routine genetic testing for clotting disorders before starting birth control is not currently recommended for everyone. However, the American College of Medical Genetics does recommend testing for women who have a personal or family history of blood clots. If that applies to you, bring it up before starting any estrogen-containing method.
Reduce Clot Risk With Everyday Habits
Physical movement is the single most practical thing you can do to keep blood flowing and reduce clot formation, especially during high-risk situations like long flights or car rides. The CDC recommends getting up and walking every 2 to 3 hours during travel. Choose an aisle seat on flights so you can move freely.
When you can’t stand up, simple seated exercises help: raise and lower your heels with your toes on the floor, then reverse it by lifting your toes while your heels stay planted. Tighten and release your calf muscles. These movements push blood through the deep veins in your legs, which is exactly where most dangerous clots form.
Staying hydrated matters too, since dehydration thickens blood and makes clotting more likely. Compression stockings are worth considering for flights over four hours, particularly if you have additional risk factors. Beyond travel, regular exercise, maintaining a healthy weight, and avoiding long periods of sitting all contribute to lower clot risk over time.
Warning Signs to Recognize
Blood clots from birth control most commonly form in the deep veins of the legs, and they become dangerous when a piece breaks off and travels to the lungs. The warning signs are sometimes taught using the acronym ACHES:
- Abdominal pain (severe or sudden)
- Chest pain or sudden shortness of breath
- Headaches that are new, severe, or come with dizziness, fainting, trouble speaking, or numbness in your arms or legs
- Eye problems like blurred vision or sudden vision loss
- Severe leg pain, redness, or swelling in one calf or thigh
A clot in the leg typically causes pain, warmth, and swelling in just one leg, not both. A clot that reaches the lungs causes sudden chest pain and difficulty breathing. These symptoms need emergency attention. Most people on combined birth control will never experience a clot, but recognizing the signs early is what separates a treatable event from a life-threatening one.