It isn’t news to most women that many birth control pills come with a variety of side effects. One of these side effects is an increased risk of developing a blood clot. Stories of young women and girls suffering stroke or death have been in the media, with teen girls as young as 14 dying from blood clots linked to hormonal contraceptives.

Any woman taking birth control pills has a slightly increased risk of blood clots. For some, the risk is even higher because of changes in their DNA. These DNA changes are usually in the clotting genes Factor II and Factor V. The DNA change (mutation) in Factor V that increases blood clot risk is called Factor V Leiden (named after the city in which it was discovered). The risk mutation in Factor II doesn’t have as interesting a name, it is known scientifically as prothrombin G20210A.

These mutations are more common in people with European ancestry. Approximately 3-8% of Caucasian women carry Factor V Leiden and don’t even know it. For Factor II, G20210A is found in 2-4% of Caucasians. About 0.4% of African Americans carry G20210A.

If you have Factor V Leiden, or G20210A, the pill may not be for you.

How do genes affect your risk of blood clots?

A blood clot is a healthy response to getting a cut, puncture, or scrape. Clotting stops bleeding and helps heal wounds. Some people inherit a decreased ability to form blood clots, with extreme cases being the rare disease hemophilia.

People with Factor V Leiden are the opposite. Normally, the Factor V gene makes a protein that helps blood clot. People with Factor V Leiden have a “super-clotting” version of the gene that is harder to “turn off”. This means blood clots form more readily in Factor V Leiden carriers.

Factor II is another clotting gene that makes the protein prothrombin. People with the G20210A mutation make more prothrombin protein than normal. This also increases your risk of blood clots.

So why is it important to know if you carry Factor V Leiden or G20210A if considering birth control pills?

People with Factor V Leiden are about five times more likely to develop a blood clot in deep veins (a condition called VTE). People with the Factor II mutation are almost four times more likely to develop a blood clot.

Newer formulations of oral contraceptives (with ingredients like drospirenone and desogestrel) can make this risk even higher – up to 1.8 times, versus older versions of the pill. Newer pills are often marketed to young women and teens as a popular choice that reduces acne and weight gain.

Before writing a prescription for birth control pills, a doctor typically uses family history, age, weight, and whether or not you smoke to determine your risk of developing a blood clot. Rarely is a genetic test ordered to screen for Factor V Leiden or G20210A.

A test for Factor V Leiden and G20210A could be life saving for your daughter, sister, or yourself. Pillcheck is quick, simple, and can be done in the comfort of your home.

Pillcheck tests for Factor V Leiden and G20210A using a saliva sample. Pillcheck also checks your response to 179 other commonly prescribed medications at the same time. It takes approximately 2 weeks to receive your results. Test results are reviewed by a licensed pharmacist who might suggest alternative medications based on your genetic data. Pillcheck results can be used for life and help to prevent side effects to many medications that any healthy person is likely to get when going for dental work or minor surgeries. This information might be lifesaving, particularly for young women considering hormonal birth control. Pillcheck can help you make a more informed decision. You can get Pillcheck for yourself or order it for your child or sibling. Click here for more information.