Here’s Why Your Period Blood Smells

From enigmatic PMS symptoms to an erratic poop schedule, your period throws some real curveballs at your body. One that is less talked about but still perplexing is the odor of your period blood itself. You're pretty sure it's harmless, but you're still dying to know what's up with it. For real, why does period blood smell like that?

To get some answers, we spoke with Taraneh Shirazian, MD, assistant professor in the Department of Obstetrics and Gynecology at the NYU Langone Joan H. Tisch Center for Women’s Health, to determine what makes your period blood smell, and if there's ever a time you need to worry about it. Here's what we learned:

"Blood itself has a certain odor," Dr. Shirazian says, adding that, as you probably already know, there's more to your menstrual fluid than just blood. You also expel bacteria, vaginal mucus, fluid, and tissue during your period, and that's why your period blood doesn't smell exactly like the blood that comes out of any other part of your body. That odor can be more or less intense, depending how long it sits in your uterus before leaving, but Dr. Shirazian says "it’s either bacteria mixed with old blood or it’s bacteria in the vagina that’s coming out with the blood" that plays the lead role in making your period blood odor special and specific to you. As far as what's normal and what isn't, Dr. Shirazian keeps it simple: "A healthy period smell just shouldn’t be fishy."

Odor can also come from the bacteria that naturally accumulates during your period. "When you’re bleeding, you retain moisture in the vagina," Dr. Shirazian says, which can lead to "secondary vaginal infections like bacterial vaginosis, which has a strong, fishy odor." The thing to remember about bacterial vaginosis (sometimes shortened to BV) is that it occurs when the bacteria that's normally found in your vagina is out of balance, and can either go away on its own or be treated with antibiotics. While BV itself isn't an STI, it is known to increase your risk for catching an STI, so if you are experiencing odor, itching, or painful urination, you should definitely see your doctor for treatment. And, if you notice an out-of-the-ordinary odor when you aren't menstruating, you might want to talk to your doctor. You may have BV, vaginitis, or some other kind of infection that requires treatment.

While there is nothing wrong with the natural blood smell (and the likelihood that it is noticeable to anyone but you is very small), Dr. Shirazian says keeping the surrounding area as dry as possible can help reduce it if it's bothering you. Try to "wear cotton underwear and breathable clothing, not a lot of spandex or tight clothing" during your period to reduce sweating, she says. Although it's not the main cause of period blood odor, sweat can definitely contribute to it. "Many types of bacteria can grow during your period that are due to both blood and sweat," Dr. Shirazian explains.

"Sometimes the issue is very heavy periods or a lot of bleeding. There’s just so much blood that it will allow bacteria to overgrow," she adds. This means that if your flow is naturally heavier, you're probably going to experience more odor than someone with a lighter flow.

If you notice that you're bleeding more than usual, or you're worried that you're bleeding excessively, Dr. Shirazian recommends talking to your doctor. "Heavier bleeding could be a sign of fibroids, polyps, or hormonal changes," she says. Plus, even if it turns out that you just have a naturally heavier flow, there's actually no reason to put up with an annoying period; you can just skip it entirely with the help of a hormonal birth control method.

The bottom line is that vaginal odor, much like vaginal discharge, is totally normal. As long as you're maintaining healthy period habits — keeping track of any weird changes to your normal cycle (including changes to the smell), changing your period protection regularly while you're bleeding, and most importantly, never, ever douching — you don't need to worry about the normal odor. As self-conscious as any odor may make you feel, there's no reason to go to extremes like douching, which, in fact, has been linked to bringing on the very infections (like BV) that cause even more (and honestly, much grosser) smells.

Sometimes smell can be a tip-off that it's time to change your tampon, pad, or menstrual cup.

Sour or sweaty smells can be a tip off that somethings not right with your hygiene, and one of the first ways to combat this is by changing your feminine hygiene product.