If you have a vagina (and even if you don’t), you probably know that every vagina has a natural scent, which is totally normal and healthy — and many people find their partner’s smell to be a turn-on. But if you notice that your vagina smells different after sex, especially if it's a "fishy" scent, that might indicate an infection like bacterial vaginosis (BV) or trichomoniasis (trich), says Alyssa Dweck, MD, a gynecologist who practices in New York.
“One of the classic symptoms of bacterial vaginosis is a fishy odor, particularly after intercourse without a condom,” Dr. Dweck explains. “There is some sort of chemical reaction that occurs with male ejaculate and discharge of the vagina when BV is present that puts off this fishy odor.” No penile penetration is required for BV, she adds, and in fact, BV is actually more common in people with vaginas who have sex with other people with vaginas.
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So, what is bacterial vaginosis? It's a common vaginal infection caused by “an imbalance of the usual bacterial environment in the vagina, and when this gets out of balance, the PH changes, and this typical fishy odor and a grayish, frothy discharge can occur,” Dr. Dweck explains. According to the Center for Disease Control and Prevention, other BV symptoms include an itchy or painful vagina and a burning feeling during urination. BV is treated with medication prescribed by your gynecologist, and because it’s not a sexually transmitted infection, if you have BV, your partner won’t need to be treated.
A fishy odor after sex is also a symptom of a common STI called trichomoniasis, or trich. “This is actually a little parasite; it’s an infection that is sexually transmitted, and it may cause that same fishy, foul odor from the vagina that is a little bit more prominent after sex,” Dr. Dweck says. Trich is treated with an antibiotic prescribed by your gynecologist, and because trich is sexually transmitted, your partner or partners will need to be treated as well. Only about 30% of people with trich experience symptoms, according to the Center for Disease Control and Prevention; for those 30%, symptoms can include itchy, burning, or sore genitals; discomfort while urinating; and a change in vaginal discharge (along with the fishy smell, it may change in texture, volume, or color).
If your vagina smells after sex, it’s most likely because of bacterial vaginosis or trich, Dr. Dweck says, but there are a few other possibilities. If your vaginal odor seems sour, after sex or just in general, and it’s accompanied by “a very thick, white discharge and an itch,” that could indicate a yeast infection. A metallic odor during period sex is common, simply because of the presence of period blood. Finally, your vaginal odor might change because of where you’re at in your menstrual cycle. “During ovulation, there’s much more copious mucus, and some women may notice a slightly different scent, with or without sex,” Dr. Dweck explains.
In general, if you've noticed an unusual change in the way your vagina smells, after sex or otherwise, it’s best to trust your perception and visit a gynecologist. People with vaginas “know their scent, so they know when something’s up,” Dr. Dweck says.