Here, eight reasons why you may be seeing blood after sex — and when you need to head to your gynecologist.

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Considering we equate blood with injury, bleeding after sex can be particularly terrifying. But, when it comes to post-coital bleeding, it’s usually not cause for serious concern, assures Makeba Williams, M.D., ob-gyn at UW Health in Madison, WI.

In fact, roughly 6 to 9% of women worldwide have bled after sex, according to a 2014 review in Obstetrics and Gynecology International — although some gynecologists believe this number is likely much higher. 

A lot of the time, the red surprise is a sign of hormones fluctuating or some kind of inflammation. That’s part of the reason bleeding post-sex is most common around 20 to 24-year-olds, when women often start birth control and issues like cervical ectropion, cervical polyps, are most likely (more on all of this below). And in roughly half of women, any instance of bleeding after sex will resolve itself, says that same study review.

But it can be a marker of something more serious — namely, cervical cancer. And because of that, you should always pay attention to and tell your doctor if you bleed after sex more than once, adds Mary Jane Minkin, M.D., clinical professor of obstetrics, gynecology and reproductive sciences at Yale University.

To soothe your anxiety until you wait for your appointment, check out the eight most common reasons women bleed after sex.

You got your period early.

The problem: If you weren't due to get your period, there's still a chance it's the cause of your spotting. Upping your exercise frequency, being uber-stressed, starting new birth control,  changes to your sleep habits — there are a ton of environmental and hormonal causes that can deliver an early or unexpected period, says Santa Monica-based ob-gyn Sherry A. Ross, M.D., author of She-ology: The Definitive Guide to Women's Intimate Health. Period.

The fix: If it happens once or twice, it’s not cause for alarm, but if your period continues to be unpredictable, be sure to tell your doctor.

You aren’t producing — or using — enough lubrication. 

The problem: If your estrogen levels are low — which happens naturally during menopause, perimenopause, or while breastfeeding — your vagina gets less blood flow. This causes the vaginal tissue to become less elastic, creating more friction during sex and potentially causing you to bleed, Dr. Minkin explains. But even among young women, if you aren’t very aroused before sex, this dryness can also create friction.

The fix: If your issue is hormonal, use an OTC moisturizer like Replens two to three times a week to keep the tissue moist. If you aren’t getting aroused enough before sex, tell your partner to spend a little longer on foreplay to up the chances you’ll get wet naturally. For either cause, come game time, use a lubricant like Replens Silky Smooth or Good Clean Love as needed during sex. 

Your hormones are causing cervical ectropion.

The problem: Another possible cause for bleeding is cervical ectropion. This is when the soft cells that usually line your cervical canal have spread to the outer surface of your cervix, where cells are normally hard. If your partner hits them during sex, you’ll bleed, Dr. Minkin explains. Some women are born with this fairly common condition, but it can also be caused by fluctuating hormones — namely, from taking the birth control pill. 

The fix: See your ob-gyn for a pelvic exam. The easiest solution may be changing your birth control. But if that’s not an option or doesn’t solve the bleeding alone, there are a number of therapies your doc can do to treat cervical ectropion — namely cauterization of the area under local anesthesia using heat (diathermy), cold (cryosurgery), or silver nitrate.

You’ve been in a dry spell — and now your partner is really big.

The problem: “Lacerations to the entrance of the vagina are a common cause of bleeding after sex if it’s been a while,” says Dr. Ross. A common cause of the small cuts and tears: a large or thick penis, and a small vaginal opening. Going deep can also cause the small lesions, she adds.

The fix: Start by lubing up liberally. If you’re still seeing small tears in your skin, Dr. Ross suggests talking to your doc about vaginal dilators, plastic tube-shaped devices used to stretch the vagina over time. While that may sound slightly terrifying, they shouldn’t cause any pain if used slowly and gently and can help keep your vagina more elastic.

You’re pregnant.

The problem: Your cervix becomes very soft when you’re pregnant, especially the closer you are to full-term. Even gentle contact with the cervix is enough to cause bleeding, Dr. Williams points out. So if your man (or toys) are well-endowed, it might cause spotting.

The fix: This is a natural by-product of your body preparing for delivery, so there’s no solution. But do mention it to your ob-gyn, especially if there’s a lot of blood, since it could be a sign of other concerns like cervical ectopy or placenta issues, Dr. Williams adds.

You have an infection.

The problem: Sexually transmitted infections (STIs) and things like yeast infections or bacterial vaginosis create inflammation in the vaginal tissue and cervix. Irritation from sex can cause the tissue to then bleed. This is especially true for chlamydia, but also gonorrhea, trichomoniasis, and herpes, Dr. Williams says.

The fix: Always use a condom when not in a mutually monogamous relationship and get an STI test after every new partner. If you experience bleeding and think it’s from an infection, go see your ob-gyn who can prescribe treatment, whether it's antibiotics or an antifungal cream.

You have cervical polyps.

The problem: Benign cervical polyps — that is, non-cancerous growths that pop up on the cervix — are quite common in women over 20, Dr. Ross explains. Docs aren't quite sure why they happen — it may be from long-term inflammation, an increase in estrogen levels, or clogging of blood vessels. But hitting one of these during sex can cause bleeding.

The fix: Your ob-gyn looks for polyps during routine pelvic exams and pap smears. Usually, they coincide with vaginal discharge and heavier-than-usual periods. If this is the cause, your doctor can perform a simple procedure to remove them in-office.

You have cervical cancer — or a precancerous condition.

The problem: The biggest concern with post-coital bleeding is that it’s a sign of cervical cancer. Fortunately, that’s rare in young women — roughly 3 to 5% of women worldwide who bleed after sex have cervical cancer. However, up to 18 percent have cervical intraepithelial neoplasia (CIN), a precancerous condition in which abnormal cells grow on the surface of the cervix, according to a 2014 review in Obstetrics and Gynecology International. That’s why you need to tell your doc about any issues.

The fix: “Cervical cancer is one disease that we can almost totally prevent by women getting the HPV vaccine,” Dr. Minkin points out. In fact, the current formula protects you from about 90 percent of cervical cancers — so if you haven’t gotten it yet, talk to your doctor.