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September 26, 2023

Taking aspirin while on birth control pills may increase the risk of blood clots, study finds

Pairing high-dose hormonal contraceptives with some common painkillers may create an adverse drug reaction, researchers say

Women's Health Birth Control
Birth Control NSAID Blood Clot Source/Image licensed from Ingram Image

People who take NSAID medications, like aspirin, while on high-dose hormonal birth control may be at greater risk for developing blood clots, a recent study finds.

Taking common pain relievers while using hormonal birth control may increase the risk of certain blood clots, new research suggests. 

People who use non-steroidal anti-inflammatory drugs – known as NSAIDS – along with high-dose contraceptives have a greater risk of blood clots than those who do not take the medications together, only use NSAIDs or use lower-dose birth control methods, the study found. Common NSAIDs include aspirin, ibuprofen and naproxen.

The study found an estimated 23 in 100,000 women developed blood clots within one week of using NSAIDs and high-dose birth control simultaneously. That was twice the rate of using NSAIDs with medium-dose birth control and nearly eight times the risk of using them with low-dose birth control. The findings suggest an adverse drug interaction, researchers said.

"The findings highlight the substantial knowledge gap that exists around hormonal contraceptives as pharmaceuticals that may interact with other drugs," Amani Meaidi, the study's lead author, of the University of Copenhagen, wrote in an editorial that accompanied the study. 

Still, Meaidi cautioned that the risk of developing a blood clot remains low even among users of high-dose contraception, at only about 0.02%. But she said women can lower their risk by switching to lower-dose birth control methods. Using NSAIDs with low-dose contraceptives does not significantly increase the risk of blood clots, the study found. 

High-dose birth control includes combined estrogen and progestin patches, vaginal rings and pills containing at least 50 mg of estrogen. Medium-dose birth control includes all other oral contraceptives and birth control injections. Low-dose birth control includes progestin-only birth control pills, implants and intrauterine devices, also known as IUDs. 

NSAIDs are the most common medications taken with hormonal birth control. Previous research has identified an increased risk of blood clots from using NSAIDs alone. 

Dr. Jennifer Wu, an OB/GYN at Northwell Lenox Hill Hospital in New York City, told Health that there are not that many alternatives to NSAIDs for pain, and that they are often used in medical settings as a way to discourage the use of narcotic painkillers that have contributed to the opioid epidemic. 

"Heat, exercise, and distraction are effective for menstrual pain," Dr. Anne-Marie Amies Oelschlager, a Seattle-based OB-GYN, told Everyday Health. "Acetaminophen is another pain reliever that appears to have a lower clotting risk and may be an option for those who wish to avoid ibuprofen, naproxen or diclofenac." 

The latest study found that pairing NSAIDs with high-dose contraceptives specifically appears to heighten the risk of venous thromboembolisms – blood clots that form in deep veins, typically in the lower leg, thigh or pelvis. They can cause fatal blockages in the vessels that send blood to the lungs, known as pulmonary embolisms. 

The study analyzed data from 2 million women over 10-year periods from 1996 through 2017. About 530,000 of them used NSAIDs and some form of birth control. None of them had a history of blood clots. Over the monitoring period, there were 2,715 pulmonary embolisms 5,995 deep venous thromboses. They led to 228 deaths. 

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