OB/GYNs Share, Once and for All, Whether Having Sex Can Make Your Period Start Early

According to OB/GYNs the general answer is sex can potentially have an impact—but only to a very limited extent.

"Having sex won't usually start your period earlier," says Lucky Sekhon, MD, fertility specialist and board certified OB/GYN. "It's theoretically conceivable, since sex can have high impact on the reproductive tract and orgasm can cause uterine contractions that may hasten the breakdown of the lining. However, this would only be the case where a [person] was already poised to get [their] period soon due to falling progesterone levels, after ovulation of an egg that did not result in pregnancy."

So essentially, having tons of penetrative sex won't suddenly jump-start your period if it's due, like, two weeks from now (if it does, consider scheduling an appointment with your medical provider). But if you're already expecting it, and if the process has already started, sex play of any kind that results in orgasm may egg on your period, so to speak. That means solo sex, non-penetrative sex acts, and sexual penetration alike can all start your period, if you're already within the window.

"If you're pretty far away from your period and you're not expecting it within the next couple of weeks, having sex will not bring it on," says Tiffany Pham, MD, an OB/GYN and medical advisor at Flo. "But the closer and closer you get to your period, that may potentially happen."

If you're already expecting it, and if the process has already started, sex play of any kind that results in orgasm may egg on your period, so to speak.

Menstrual phases and menstrual cycle length

While having sex may play a role in hastening your period if you are already expecting it in the next couple of days, to get a better idea of the role sex can play in having your period, we need to get back to a little bit of menstrual cycle 101. A normal menstrual cycle is between 25-35 days on average, says Dr. Pham.

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During the first half of your menstrual cycle, called the follicular phase, your ovaries release eggs into the fallopian tubes that could be potentially fertilized by sperm. The follicular phase is actually where variation in period length comes from, because the length of time it takes for an egg to mature in the fallopian tubes — which is what means it's ready for a sperm and is the actual ovulation— can differ from one month to the next.

The luteal phase is when the follicle that released that egg becomes known as a "corpus luteum," and produces progesterone. When your body realizes an egg hasn't been fertilized, the corpus luteum dies, and stops producing that progesterone—which is what causes period cramps and other fun PMS symptoms—as well as your uterus to shed its lining, thus beginning your period.

Dr. Pham says the follicular phase can be from around 10 - 20 days long, and may not last the same amount of time every month. In contrast, a normal luteal phase length is around 14 days, and should be consistent each cycle.

"The variation in your cycle length and when your period will come that month is predetermined by the fact of how long your follicular phase is," Dr. Pham says.

So if you think your period is early, you might actually just be having a shorter cycle than usual—which is par for the course of having a period.

"It's actually fairly normal for your period and your period blood color to fluctuate from month to month," Dr. Pham says. "It's actually more common for that to be the case than rather for people to have 28 day cycles every month."

The caveat here is if your period is outside of the normal cycle length range, or if you are seeing a large variation from month to month.

"For example, [if your menstrual cycle lasts] 24 days one month, 35 days, the next month, 25 days a month after that, that's too big of a variation from a month to month," Dr. Pham says, and you may want to talk with your doctor.

Starting to track your period by hand on a calendar or by using a period tracking app like Flo is a good way to monitor whether your menstrual cycle length fluctuations are within a normal range.

Can having sex make your period come sooner or later?

Now that we know that most of the variation in period happens during the follicular phase, it's easier to understand the limited role sex may play in the onset of your period.

"Beyond delaying your period because you get pregnant, sex cannot usually bring on or induce your period," Dr. Pham says.

Having sex during the follicular phase won't impact when you ovulate, and therefor won't impact the length of that phase.  Having sex during the luteal phase won't do diddly squat, with the exception of sex at the very end of the menstrual cycle thanks to the uterine contractions that might happen if you have an orgasm.

"Contractions of the uterus essentially will allow for the breakdown of the lining of the inside of the uterus," Dr. Pham says. "That uterine lining is what essentially sheds every month in the period. So when you have those uterine contractions, it can cause and initiate the breakdown of that lining and then initiate your period."

Bleeding after sex

If you notice that you start bleeding after having sex and you are not on your period, there are a few things to consider. The first is, where are you in your menstrual cycle? If you have just recently finished your period, sex could be causing just the last dregs of uterine lining to be expelled, and this is perfectly normal.

"The orgasm leading to the uterine contractions can actually cause whatever is left inside the uterus to become expelled with a contraction and therefore cause you to have a little bit more bleeding than what you would expect," Dr. Pham says. "You think your period's almost done, but you have sex, you have that orgasm, and then a little bit more is just pushed out."

However, if you are completely done with your period, or if bleeding or cramping after sex is something that happens frequently, you may want to consult a physician. Bleeding after sex could be a sign of a structural abnormality of the cervix, including a cervical polyp, cervical cancer, an infection, or an STI.

"If your period has completely stopped and then you have sex and you notice bleeding afterwards, or if you notice bleeding after sex fairly frequently, that can potentially be a cause for concern," Dr. Pham says. "If you find that you're bleeding consistently after intercourse, then it's definitely important to get evaluated by a provider to make sure that those particular things are ruled out."

Can anything else cause your period to come early?

"Beyond the use of hormones, there really isn't a surefire way to induce or delay your period," Dr. Pham says. Some supplements or naturopathic blogs may tout the use of herbs or foods, but these strategies aren't supported by data.

"In the world of supplements and natural remedies, you might hear about parsley tea, turmeric, ginger tea, pineapple, apple cider vinegar, those type of remedies potentially being able to induce your period, but there really isn't any good strong evidence behind that," Dr. Pham says.

Be prepared

The relationship between orgasms and periods beginning is potentially great news if you’re looking for a way to kick-start your menstrual cycle when it feels a little delayed (nothing like an orgasm to keep you flowing). But what if you're now worried about having that just-under-the-wire sex a day or so before you expect your period? Won’t somebody please think of the bedsheets?

Well, there are practical ways to troubleshoot any period leakage. For example, if you're really paranoid it might start as a result of your sex sesh, you can invest in a product like Flex Disc ($13), an insertable alternative to tampons and pads that can facilitate mess-free period sex. Likewise, if you're looking to protect those high thread count sheets, you might want to invest in a period blanket. (The Liberator Fascinator Throw Moisture Proof Blanket ($99) comes with high recommendations from sex writer Gabrielle Kassel.) It's also a multi-purpose product in that it can be gloriously used to shield your bed from scheduled period leakage, other byproducts of sex—and other liquids, if you're simply a messy drink-coffee-in-bed person like I am.

And if your period does show up unexpectedly following your orgasm and you (and your bedspread) are completely unprepared? Well, take your magnesium for cramps to stem the tide of your suffering, break out some hydrogen peroxide for the stain, and keep it moving.

Looking for other things to help support your period? Here's how to eat for every phase of your menstrual cycle: