Can Sex Kick-Start Your Period? Here’s What Experts Say

Some people have been surprised to find that their period came early after having sex. What’s the correlation? Is there one? Here’s what experts say.

Can Sex Kick-Start Your Period? Here’s What Experts Say

Can Sex Kick-Start Your Period? Here’s What Experts Say

Can Sex Kick-Start Your Period? Here’s What Experts Say

8 minute read

Whether you’ve had your first period or are about to have your 200th period (we commend you), you may be wondering, “Can sex kick-start your period?” After all, sex can have many effects — lowering blood pressure, blocking pain, acting as exercise — and perhaps you’ve even gotten your period right after having sex. Which could be a good or bad thing. (On one hand, maybe it’s a relief. On the other, periods can suck.) So, what’s the deal?

To figure out if sex can make your period come sooner than expected (and discover more about the connection between sex and the menstrual cycle) we reached out to several OBGYNs for more information. We also discussed other conditions that can cause one to bleed after sex. Note: If this is happening to you, make an appointment with your healthcare provider to see what’s going on.

Can sex kick-start your period? 

“Having sex will not kick-start a period,” OBGYN Dr. Mary Jane Minkin tells O.school, adding that there are other conditions (mentioned down below) that can cause bleeding after sex. For instance, if it’s too dry during penetrative sex, the friction can be uncomfortable and cause bleeding.

N.Y. gynecologist Dr. Alyssa Dweck adds, “[If] you’re just about to get your period, but haven’t started to bleed yet, and you have sex and climax, it’s surely possible for the uterine contractions experienced during orgasm to facilitate or expedite the initial light flow.” The same thing can happen when you believe your flow is done — an orgasm can cause uterine contractions that release residual blood.

As for what does cause a period to start, Dr. Minkin states that it’s the drop in progestrerone levels at the end of the menstrual cycle — which is a cycle influenced by hormones, not sex. 

To understand exactly how sex can make your period seem like it’s starting sooner, first we need to know exactly how the uterine lining (called the endometrium) changes throughout the menstrual cycle. Starting with the last day of your period, when bleeding is complete, the endometrium is a thin layer of cells. As the cycle enters the the proliferative phase, the endometrium thickens thanks to rising estradiol (a reproductive hormone that influences the menstrual cycle). This is the time during which the endometrium is growing to support a pregnancy if one occurs.

Ovulation occurs next, and usually an egg is released from the ovaries. During this phase, glands in the endometrium rearrange to provide nutrients to the uterus that can help keep a pregnancy healthy. Following ovulation, the secretory phase will be different depending on whether or not there is a pregnancy. In cases where there’s no pregnancy, two reproductive hormones called estradiol and progesterone encourage the uterine lining to break down. The endometrium also secretes prostaglandins that tell the uterus to cramp. This results in the endometrium being sloughed off as menses begins. 

If one is about to menstruate, sex can make period blood exit the body sooner because orgasm causes uterine contraction that are similar to the natural uterine contractions caused by prostaglandins. 

When we posted the question “Has having sex ever made your period come early?” on Twitter and Instagram, we got several responses from those who say that sex has made their period come early. 

“Okay, so sex always affects my period,” Krystal P. tells O.school. “It'll make it happen early since orgasms tend to jumpstart your cycle. If I'm in a consistent relationship, my period changes during that time.” Another anonymous responder seconds this, explaining, “My periods are already irregular, since I have endometriosis and ovarian cysts. Sometimes if I do have sex, I can bet my period will come for a few days or be a full-blown period. I don’t know if they’re related, but that’s just what happens.”

Kellie K. says that the same has happened to her, stating, “Yes, it has — particularly if I have penetrative sex within one to two days of when it is supposed to start. In fact, times that it’s been a few days late, or I’ve wanted it to start a bit early, penetrative sex has been a nice way to give a little ‘Hello!’ to my uterus, though it certainly doesn’t work every time. Alternatively, if I have penetrative sex too soon after my period has ended, it can sometimes cause bleeding to start again.”

Another user was even experiencing this when answering our Instagram query. “Had sex last night and got my period today. Four days early,” writes @keytomore. 

What about your very first period? Can having sex before cause you to menstruate earlier? 

Again, the answer is no. Gynecologist Dr. Nina Carroll of Your Doctors Online tells O.school, “Having sex will not change the timing of menarche, which is a [person’s] first menstrual period, or any subsequent period after that, unless [they] become pregnant. [T]hen there is no period.” 

However, Dr. Minkin emphasizes that pre-menarche sex can still lead to pregnancy and the transmission of STIs. “Anyone thinking about having sex should be seeing a healthcare provider to talk about birth control,” she says. “Planned Parenthood is an excellent choice to visit to discuss these issues. And if you cannot see a provider, and want to have sex, make sure you are using a condom [or other forms of protection], to help prevent both pregnancy and the spread of a sexually transmitted disease.” 

What else can cause you to bleed after sex?

Dr. Carroll states that if one is experiencing their period more often than monthly, that can signify the following issues: 

  • The menstrual cycle is anovulatory, meaning ovulation did not occur
  • Thyroid imbalance
  • Not taking birth control pills as prescribed

If you are experiencing irregular periods, visit your gynecologist or healthcare provider as soon as possible. 

According to Dr. Dweck, bleeding after sex — which can be mistaken for an irregular menstrual cycle, and vice versa — can be a sign of:

  • Vaginal dryness
  • An imbalance of vaginal flora
  • STIs like gonorrhea or chlamydia
  • A tear in the hymen
  • A growth in the vagina or cervix, such as a benign polyp, fibroid, or very rarely, cancer
  • A precancerous abnormality on the cervix (this is typically picked up on pap smear)

“The most serious, but least common, are cervical cancer and uterine cancer,” adds Dr. Carroll, referring to reasons why one might bleed after sex. Though you likely aren’t dealing with the previously mentioned cancers, you should visit your healthcare provider as soon as possible for proper diagnosis and treatment. 

So while sex can’t exactly cause your period to come early, it can make it visible sooner. If you experience bleeding after sex and aren’t sure what’s going on, contact your healthcare provider.

Anna Gragert

Reviewed for Medical Accuracy

When Anna isn't trying to create a groundbreaking third-person bio for herself, she's working as a freelance writer, editor, and content strategist. She was previously the deputy editor at So Yummy and lifestyle editor at HelloGiggles, and has worked with publications such as Teen Vogue, Nylon, InStyle, Glamour, Bust, Catapult, and more.

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