What You Need to Know About Birth Control and Blood Clot Risk

Blood clots are a natural response to cuts and injuries, but they can be dangerous when they form in the wrong place at the wrong time. Some forms of birth control can increase the risk that your body will make abnormal blood clots. This can be a problem, especially if the clots go to your lungs and cause a pulmonary embolus. Still, for most people, the risk of blood clots with birth control is actually lower than the risk of blood clots caused by being pregnant. 

How does birth control increase your risk of blood clots?

Blood clotting is a carefully balanced process that stops you from bleeding out after an injury. There are proteins in blood that form clots and proteins that stop clots from forming. These proteins go up or down depending on the body’s needs. They balance the blood so it’s thin enough to avoid unwanted clots, but sticky enough so clots can form fast when needed. 

But hormonal birth control can tip the scales. Hormonal birth control can increase the risk of blood clots in a few ways: 

• They increase the blood proteins that stimulate clot formation.

• They reduce levels of blood proteins that prevent clot formation.

• Birth control hormones may also slow the body’s natural process of dissolving a blood clot, but that evidence is not as clear.

The higher the dose of estrogen in birth control, the greater the risk of blot clots. Other hormones in birth control can also mimic the effect of estrogen, like third-generation progestogens, drospirenone, and cyproterone.

Which birth control methods increase your risk of blood clots?

Birth control only changes your risk of blood clots if it contains hormones. Most hormonal birth control options — but not all — have varying amounts of the hormones estrogen and progestin. That’s why they’re called “combined” contraceptives. 

The risk of blood clots depends on the type and dose of estrogen and progestin in birth control. Mostly, it’s the estrogen that increases the risk of blood clots, although some newer progestins may also increase this risk. 

So, any form of combined hormonal birth control that includes estrogen has the potential to increase the risk of blood clots. The risk of blood clots depends more on the dose of estrogen than on the form it comes in. 

Hormonal birth control methods that increase the risk of blood clots

There are several hormonal birth control methods that increase the risk of blood clots, including:

• Combined oral contraceptive pills: The risk of blood clots is 3 to 4 times as high in people who use the newest (third and fourth generation) birth control pills (like Apri and Yaz) compared with similar people who are not on birth control. Second-generation birth control pills (like Portia and Cryselle) have a slightly lower risk, about 3 times compared with baseline. 

• Vaginal rings: Vaginal rings (like Nuvaring and Annovera) combine hormones and increase the risk of blood clots by 6.5 times compared with non-hormonal birth control.

• Birth control patch: The patch (Xulane) also combines hormones and increases the risk of blood clots by nearly 8 times.

• Birth control shots: Even though these are progestin-only shots (like Depo-Provera), they can increase the risk of blood clots by about 3.6 times compared with baseline.

Birth control methods that do not affect the risk of blood clots

The following birth control methods do not significantly affect the risk of blood clots:

• Intrauterine devices (IUDs), including hormonal IUDs and copper IUDs

• Progestin-only implants and pills

How common are blood clots from birth control?

Whether or not you use birth control, there’s a small chance a spontaneous blood clot can develop. Hormonal birth control can more than triple the risk of blood clots, but the risk remains low. And the risk of blood clots during pregnancy and for the first 6 weeks after birth is even higher than with most types of birth control. 

It’s also worth noting that the risk of blood clots with hormonal birth control pills is highest in the first 6 to 12 months of use. The risk also drops down to baseline after someone stops hormonal birth control. 

Who has a higher risk for blood clots? 

The risk of blood clots from hormonal birth control is higher after the age of 40. That’s in part because the baseline risk of blood clots increases with age. 

Smoking also increases the risk of blood clots. So if you’re 35 years old or older and you smoke, experts do not consider it safe to use combination hormonal birth control (any pill, patch, or ring) that contains estrogen. 

There are also other groups of people with a higher risk of blood clots. For these people, combined hormonal birth control might be risky, especially if they have more than one of the following risk factors:

• Clotting disorders, like factor V Leiden

• Prior blood clot, heart attack, or stroke

• Other medical conditions that increase the risk of clots, like cancer, lupus, heart disease, uncontrolled high blood pressure, diabetes, or polycystic ovary syndrome (PCOS)   

• Obesity with a BMI over 30 

• Prolonged immobility, like from hospitalization 

Keep in mind that it’s not always clear that a person is at risk of a blood clot. As many as 25% to 40% of abnormal blood clots occur spontaneously. This means that, in many cases, someone has a blood clot without knowing why. 

What can you do to reduce your risk of clots?

The risk of blood clots with birth control is low, but you can take action to reduce your risk even further — especially if you have a higher risk than normal of blood clots.

1. Choose a ‘low hormone’ birth control method

If you want to use hormonal birth control, but you’re worried about blood clots, choose one that is less likely to increase the risk of clots. Examples include a levonorgestrel IUD, or a progestin-only method, like the norethindrone pill, or the implant.

Some combined pills with levonorgestrel or norgestimate have a lower risk of clots than other combined hormonal contraceptives. Examples include Vienva, Ortho Tri-Cyclen, and Jolessa.

2. Stop smoking

If you smoke, try to stop. Smoking cigarettes increases the risk of blood clots for anyone taking combined hormonal birth control. Whether you’ve tried to stop before or this is your first time, there are plenty of methods that work. And there are a lot of resources to help you on your smoking cessation journey. 

3. Choose hormone-free birth control

There are also non-hormonal birth control options that do not increase the risk of clots at all, like the copper IUD and Phexxi, the vaginal gel. 

If you’re sure you never want to get pregnant again, a tubal ligation or removal is a good choice for permanent birth control. Vasectomy is another definitive option for birth control.

Barrier methods of birth control, like external (male) and internal (female) condoms, are a good option since they also reduce the risk of sexually transmitted infections (STIs). Diaphragms are placed at the top of the vagina to prevent undesired pregnancy when used with a spermicide. Cervical caps are like diaphragms, but a provider needs to fit them. 

Why trust our experts?

Written by:

Khama Ennis, MD, MPH, FACEP

Dr. Ennis is a board-certified emergency physician based in western Massachusetts. She is the medical staff president and associate chief of emergency medicine at Cooley Dickinson Hospital.

Edited by:

Sophie Vergnaud, MD

Sophie Vergnaud, MD, is the Senior Medical Director for GoodRx Health. A pulmonologist and hospitalist, she practiced and taught clinical medicine at hospitals in London for a decade before entering a career in health education and technology.

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