Can You Get an STI During Your Period?

Having sex during your period has amazing benefits—studies show that it can help relieve menstrual cramps and ease the fatigue that tends to hit at this time of the month.

However, having sex during your period can also raise the chance for sexually transmitted infections, or STIs. It's possible to not only get pregnant during your period but also to contract an STI, said Sherry A. Ross, MD, women's health expert and author of She-ology: The Definitive Guide to Women's Intimate Health. Period.

Furthermore, women, in particular, are greatly affected by STIs; more than 9 million women get infected with an STI annually and have more issues from them than men do, according to the Office on Women's Health (OWH).

So if you decide to have sex on your period, you'll want to do it safely. Here's what you need to know about STIs and your period.

What Are STIs—and How Do They Spread?

An STI occurs when foreign agents—like bacteria or viruses—enter the body through sexual contact and cause an infection. People "can pass it to others through contact with skin, genitals, mouth, rectum, or body fluids. This includes contact through vaginal sex, anal sex, or oral sex," according to the American College of Obstetricians and Gynecologists (ACOG).

This means that for anyone with an STI who engages in any unprotected sexual activity, it is possible to get an STI at any time—including during menstruation.

What Could Increase Your Risk of Getting an STI on Your Period?

On a non-period day, your vagina naturally has a protective acidic pH, which helps prevent the transmission of certain STIs, said Mary L. Rosser, MD, a gynecologist at Columbia University in New York City. You typically can have a vaginal pH between 3.8 to 5.0, but when you're menstruating, the vagina becomes less acidic and more alkaline, making it easier for microbes to survive and thrive in your reproductive tract, according to research published in 2021 in Diagnostics.

Also, during your period, the cervix opens slightly to allow blood to pass from the uterus, said Dr. Rosser. "When this happens, bacteria and viruses can travel into the upper cervix and uterine cavity."

Which STIs Are Most Concerning?

Bacterial infections such as chlamydia and gonorrhea can be especially dangerous when you're on your period. Once they get beyond the cervix, they can turn into pelvic inflammatory disease, a more serious infection of the reproductive tract that can affect your fertility, according to MedlinePlus.

Human immunodeficiency virus (HIV) and hepatitis can also be dangerous to contract when you're menstruating. "Period blood is the perfect petri dish for spreading disease," Dr. Ross said. "Bloodborne sexually transmitted infections like HIV and hepatitis love the nutrients that a period has to offer."

How to Prevent STIs

We do not want to deter you from having sex during your period. But if you're going to do it and you're not 100% sure your partner is STI-free, use protection.

You can prevent STIs without abstaining from sexual activity, such as by getting vaccinations and using condoms, according to the Centers for Disease Control and Prevention (CDC). You and your partner may also decide to get tested so that you're aware of each other's STI status before sex.

Overall, "(i)f you're smart and strategic, you can still have a great time," said Dr. Ross. So keep yourself protected and follow the same protocol as you would on any other day.