We know you read every word of the information insert that comes with your pill pack and listen intently to the voiceover listing off warnings in drug commercials, so you may already be familiar with the risk of blood clots that comes with hormonal birth control. But how worried should you really be — and do the benefits outweigh the risks? Here’s what you need to know:
What’s going on?
If you’ve ever scraped an elbow, cut your leg shaving, or chopped vegetables a little too enthusiastically, you’ve seen the blood clotting process at work — platelets and proteins in your blood plasma work together to form a clot and prevent excessive bleeding. Usually, your body dissolves those clots naturally. But in very rare cases, clots don’t work as they should, forming on the inside of blood vessels when there’s no injury or not dissolving on their own. From there, those clots can block blood flow or even detach and travel to the lungs.
What does the Pill have to do with it?
“The hormones, mainly estrogen, in the Pill can make your blood thicker than usual” explains Dr. Sherry A. Ross, MD, a California-based OB/GYN and author of She-ology. The Definitive Guide to Women’s Intimate Health. Period. In rare cases, that can cause more clotting than usual. If you’re already prone to clots or have other risk factors, you’re at higher risk of those clots becoming dangerous.
Estrogen is also responsible for the slight increase in blood pressure seen in women taking the pill, Dr. Sherry adds — and uncontrolled high blood pressure can up your chances of developing a clot, too. The damage can be serious — blood clots can cause chest pain, heart attack, stroke, and pulmonary embolism — but you’re hardly playing Russian roulette with every pill you take. If you’re healthy, your risk is small. “Developing a blood clot on the birth control pill is rare,” says Dr. Sherry.
What are my risk factors?
A family history of high blood pressure, extra weight, lack of physical activity, heavy alcohol use, and smoking can all put you at a greater risk of developing high blood pressure, so being upfront with your doctor is essential — otherwise, you might end up on birth control that increases your risk even more. And yes, an occasional cigarette counts. “Women who are ‘social’ smokers don’t always admit to being smokers,” says Dr. Sherry. “Social smokers are also at risk for blood clots while taking the pill, especially for those over 35 years old.”
For a healthy woman not taking a pill that contains both estrogen and progesterone — aka a combination pill — only 2 in 10,000 are at risk of developing a clot. For women who are taking a combination pill, the risk is 12 out of 10,000 depending on the pill. The jump may seem big, but the overall risk is still low — and still lower than your risk when it comes to other factors, like pregnancy. “During pregnancy, your risk of developing a blood clot is 20 in 10,000 pregnancies.” And the risk that comes with long flights is even higher, with one study finding an incidence rate of 3.2 out of 1,000. Plus, when you stop taking hormonal birth control, your risk of blood clots goes back to normal. “Overall, the birth control pill is safe, highly effective, and the other health benefits outweigh the risks,” says Dr. Sherry.
Bottom line: Overall, the risk of developing a blood clot is very low, but your personal risk factor really depends on the exact hormonal birth control you’re taking, your health deets and habits, your family history, and more. Schedule some one-on-one time with your gyno to get the lowdown on the best choice for you — and don’t fret; even if the pill isn’t an option, a long-term and effective contraceptive like a non-hormonal IUD might be.