What Causes Period Blood To Smell?

Here's when it could be a sign that something isn't right.

You may have noticed that your period comes with a lingering odor every month. You might not always smell it, but when you do get a whiff, it's less than pleasant. Way less.

Periods smell: That's no secret. However, when you get a cut on your finger, for example, the blood doesn't have any smell at all. So why does that time of the month bring a particularly unpleasant odor?

Vaginal Bacteria

Christine Greves, MD, an ob-gyn at the Center for Obstetrics and Gynecology at Orlando Health in Florida, told Health that vaginas are home to many different bacteria, and when that bacteria mixes with blood, it produces an odor. Simple as that.

"When you cut your finger, you wipe the blood off right away, and it's fresh blood, meaning it hasn't been sitting around for a while," Dr. Greves said. "But period blood stays in the vagina for a longer period of time. It's exposed to the bacteria in the vagina, and that's where you get that odor."

You might also notice that it doesn't always smell the same. The amount of bacteria in the vagina fluctuates, which can change the smell. A slight change is usually nothing to worry about, Dr. Greves said, but if all of a sudden your period smells seriously rotten, you may want to talk to your healthcare provider.

Bacterial Vaginosis

According to the Office on Women's Health (OWH), a particularly strong, fishy smell could be a sign of bacterial vaginosis, an infection caused by an overgrowth of bacteria in the vagina. Other symptoms include burning (especially during urination), itchiness, and abnormal vaginal discharge. Any of these symptoms should be a cue to get a professional opinion.

Prolonged Tampon Use

A rotten smell, on the other hand, could be a sign that you've left a tampon in for too long, Dr. Greves said. Of note, though it is rare, having a tampon in for a prolonged amount of time could lead to toxic shock syndrome (TSS), a toxin-caused condition from certain types of staphylococcus bacteria, per MedlinePlus—which is all the more a reason to get checked out.

Can't remember whether you took your tampon out? Feel around the opening of your vagina for a string or feel inside for the tampon itself. If you're still not sure, go see your healthcare provider.

How To Minimize Period Blood Smell

If you don't have an infection but just want to keep your normal period smell to a minimum, Dr. Greves said changing your tampon or pad frequently is key. How often you need to change to avoid any odor will depend on your flow. Researchers of an April 2022 study in the Open Journal of Obstetrics and Gynecology suggested a changing time of every three to four hours. You can experiment to see what works for you.

Menstrual cups are also another option for decreasing period blood smell. Researchers of a July 2019 study in The Lancet Public Health stated that "[m]enstrual cups are made of medical-grade silicone, rubber, latex, or elastomer and can last up to 10 years; disposable single-use menstrual cups also exist." Basically, the cup is inserted into the vagina and collects blood instead of absorbing it, which minimizes the unpleasant smell. It can then be emptied, washed with soap and water, and reinserted—giving you the ability to have multiple uses of the cup during your cycles for up to one year.

Proper hygiene should be enough to make the smell manageable. But whatever you do, do not use a douche or deodorizing products, such as wipes and sprays. These throw off the natural bacteria in your vagina and cause infection.

Change tampons or pads regularly, wear clean and breathable underwear, and be mindful of possible infections. A little smell is nothing to be ashamed of, and remember, you're probably the only one who may notice it anyway.

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