Vaginal bleeding after a workout can be alarming. And if it happens more than once or twice, it could be a sign of an underlying problem that needs to be addressed.
"Spotting after exercise isn't that common, and it usually does indicate that something is a little abnormal with a woman's hormones or anatomically," says Jennifer Wu, MD, an ob-gyn at Lenox Hill Hospital in New York.
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Here, Dr. Wu shares some of the most likely reasons why exercise can cause spotting and what you can do about it, plus other possible culprits behind bloody discharge after exercise that may not necessarily be tied to your workout.
1. You Have a Polyp
Uterine polyps are small, noncancerous growths that can cause heavy or irregular periods and spotting in between periods. They typically stay within the uterus but sometimes can extend into the opening of the cervix or the vagina.
Spotting from a polyp can happen anytime, but it may be more likely after exercise or sex because polyps can bleed from irritation or contact, Dr. Wu explains.
Risk factors for uterine polyps include being perimenopausal or postmenopausal, having obesity, taking tamoxifen (medication for breast cancer) and taking hormone therapy to help manage symptoms of menopause, according to the Mayo Clinic.
Fix it: Sometimes small polyps can clear up on their own over time. But in some cases, your gynecologist may recommend hormonal medications to reduce bleeding from a polyp or outpatient surgery to have the polyp removed, according to the Mayo Clinic.
2. You Have Very Low Body Fat
While specific numbers vary, reaching a very low body fat percentage can cause your period to become irregular, which could lead to spotting during exercise or at other times. (In some cases, low body fat can also make your period stop altogether. Doctors call this exercise-induced amenorrhea.)
"This typically applies to extreme athletes with a lot of muscle mass," Dr. Wu says. "It's more common during training season, and then periods may become more normalized during the off season."
In some cases, exercise-induced period loss can also happen from not eating enough.
Fix it: See your doctor if you're concerned that your body fat levels have affected your period. Amenorrhea can increase the risk for osteoporosis and may mean you're not getting enough energy to adequately fuel your exercise, the Cleveland Clinic notes.
3. Your Clothing Is Causing Chafing
Sometimes what appears to be spotting could actually be caused by chafing while you're working out. This might be the case if you see bright red spotting after exercise — that color is more likely to be caused by an injury (as opposed to dark red or brown spotting, which is more likely to come from inside the body).
"Irritating clothing could cause bleeding externally or at the entry of the vagina," Dr. Wu says.
Fix it: Try changing up your workout clothes. Stretchy, form-fitting bottoms work well for higher-intensity activities like running or biking; looser ones can be good for walking, gentle yoga or strength-training. Pay attention to material, too: Moisture-wicking fabrics like polyester or polypropylene are a better choice than slow-drying ones like cotton, per the National Library of Medicine.
And consider incorporating anti-chafing products into your routine.
4. Other Causes of Spotting
Spotting can have a number of other causes. But they're not typically linked to exercise specifically, so breakthrough bleeding can happen at any time, Dr. Wu points out.
According to the Cleveland Clinic, these can include:
- Hormonal shifts caused by birth control pills or IUDs
- Medical conditions, like bleeding disorders, thyroid problems, polycystic ovary syndrome (PCOS), adenomyosis, uterine fibroids, cervicitis or endometrial hyperplasia
- Miscarriage or other pregnancy complications
- Hormone replacement therapy
- Sexually transmitted infections
- Cervical or endometrial biopsies
- Stress
When to See a Doctor
Spotting just once or during a single month — whether while exercising or not — likely isn't anything to worry about. But between-period bleeding that happens more often isn't normal and could be a sign of an underlying problem.
"If it's been happening for more than two or three months, I'd see the doctor and get a workup," says Dr. Wu.
- Mayo Clinic: "Vaginal Bleeding"
- Harvard Medical School: "Dysfunctional Uterine Bleeding"
- U.S. Office on Women's Health: "Physical Activity and Your Menstrual Cycle"
- U.S. National Library of Medicine: "The Effect of Physical Activity Across the Menstrual Cycle"
- American Council on Exercise: "9 Signs of Overtraining to Look Out For"
- U.S. National Library of Medicine: "Post Exertional Hematuria"
- Cleveland Clinic: "Abnormal Uterine Bleeding"
- Mayo Clinic: "Uterine Polyps"
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Is this an emergency? If you are experiencing serious medical symptoms, please see the National Library of Medicine’s list of signs you need emergency medical attention or call 911.