Spotting After Exercise? Here's What Your Body's Trying to Tell You

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.

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.

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.

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.

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.

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
  

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.