How Common Are Blood Clots?
Blood clots are generally rare, but they can occur even in otherwise healthy people, including those who are not taking CHCs. Out of every 10,000 women who are neither pregnant nor using CHCs, between 1 and 5 will experience a blood clot every year. Women using CHCs have a slightly higher risk: between 3 and 9 in every 10,000 CHC users experience a blood clot in a given year.
What Types of Blood Clots Are There?
"Venous blood clots" or "venous thromboembolisms" (VTEs) are a mass of thickened blood inside a vein. Many people are familiar with deep vein thrombosis (DVT) and pulmonary embolism (PE), which are types of VTE. VTEs can travel through the bloodstream, damaging vital organs and even resulting in death. VTEs are the third-most common type of cardiovascular illness in the U.S. and cause 300,000 deaths annually.
Who's at Risk of Getting Blood Clots?
The highest risk of blood clots among reproductive-aged women occurs during pregnancy and in the postpartum period, when estrogen levels increase. Among pregnant women, between 5 and 20 in every 10,000 pregnant women will experience a blood clot in a year; 40 to 65 in every 10,000 postpartum women experience a blood clot in a year.
What Are Combined Hormonal Contraceptives (CHCs)?
Birth control methods that contain the hormones estrogen and progestin are called combined hormonal contraceptives (CHCs). CHC products include birth control pills, patches, and vaginal rings. While all CHCs carry some risk of blood clots, the risk can differ from product to product.
What Are the Signs and Symptoms?
Some people experiencing a blood clot have no signs or symptoms at all. When symptoms do occur, depending on where the blood clot is located in the body, people may experience some or all of the following:
- redness of the skin
- difficulty breathing
- faster than normal or irregular heartbeat
- chest pain or discomfort
- coughing up blood
- very low blood pressure, light-headedness, or fainting
People experiencing any of these symptoms should seek medical care immediately.
So, although CHCs increase the risk of blood clots, the risk is only slightly higher than the risk for women who don't use CHCs, and is significantly lower than the risk faced by pregnant women. Some personal characteristics and medical conditions increase the risk of blood clots, including (but not limited to):
- genetic clotting disorders
- being over age 60
- prolonged inactivity (such as during long car or airplane rides)
Individuals with characteristics that increase their risk of blood clots should discuss the risks of using CHCs with their health care provider and/or pharmacist.
- The World Health Organization: Combined Hormonal Oral Contraception and Risk of Venous Thromboembolism (VTE)
- The Centers for Disease Control and Prevention: Deep Vein Thrombosis (DVT)/Pulmonary (PE) - Blood Clot Forming in a Vein
- The American College of Obstetricians and Gynecologists, Committee on Gynecologic Practice: Risk of Venous Thromboembolism Among Users of Drospirenone-Containing Oral Contraceptive Pills
-  Ozaki A, Bartholomew JR, Venous Thromboembolism (Deep Venous Thrombosis & Pulmonary Embolism), Cleveland: Cleveland Clinic Center for Continuing Education, 2012.
-  U.S. Food & Drug Administration (FDA), FDA Drug Safety Communication: Updated information about the risk of blood clots in women taking birth control pills containing drospirenone, Rockville (MD): FDA, 2013.
-  Allina A, “Contraceptive Safety Concerns: What’s a Responsible Feminist to do?” The Women’s Health Activist 2012; 37(3):4-5.
-  American College of Obstetricians and Gynecologists, Committee on Gynecologic Practice, “Risk of venous thromboembolism among users of drospirenone-containing oral contraceptive pills (Committee Opinion No. 540),” Obstet Gynecol 2012;120:1239–42.
-  Lidegaard Ø, Hougaard Nielsen L, Skovlund CW, and E Løkkegaard. “Venous thrombosis in users of non-oral hormonal contraception: follow-up study, Denmark 2001-10,” BMJ 2012; 344:e2990.
-  Centers for Disease Control and Prevention (CDC), "Venous Thromboembolism (Blood Clots),” Atlanta: CDC, 2015.
-  Batur P, Female Contraception, Cleveland: Cleveland Clinic Center for Continuing Education, 2016.
This fact sheet is meant to provide current and potential contraceptive users with information to help weigh the risks and benefits of using hormonal contraception. Readers are encouraged to consult their health care providers and/or pharmacists for a more detailed discussion of the risks of using combined hormonal contraception.