Exercise and the Taste of Blood

Exercise causes your body to produce a lot of fluids, some of which can leave a strange taste in your mouth. If you taste blood after running, you might be wondering if it's normal or if it's a sign that something more serious is going on. Read on for the basics.

Health experts agree it's not uncommon to taste blood after running or doing any type of intense physical activity. And sometimes you won't even see any blood in your saliva.

According to David Nazarian, MD, a primary care physician at My Concierge MD in Beverly Hills, California, there are several reasons you might taste blood or experience a metallic taste in your mouth during and after intense workouts, including running.

"This can happen due to an oral tooth cavity or tooth-related issue or infection," says Dr. Nazarian. The Cleveland Clinic notes that poor oral hygiene such as periodontitis, gingivitis and tooth infections may contribute to a metallic taste in your mouth.

But what does your dental health have to do with tasting blood while working out? Dr. Nazarian says that because activity increases blood flow, any tooth decay or salivary gland blockage could cause you to taste blood.

Another less common cause of a metallic taste in your mouth is what's called "burning mouth syndrome," according to the Mayo Clinic. That's a chronic burning feeling in the mouth that results in side effects such as a bitter or metallic taste.

A blood taste in your mouth can also result from fluid that accumulates in the small air sacs of the lungs during intense aerobic exercise, such as running, according to the Wexner Medical Center at Ohio State University.

Exercise can also increase pressure in the lungs, and that, Dr. Nazarian says, can lead to red blood cell leakage in parts of the lung responsible for air and gas exchange. "This leakage can cause red blood cells to burst in the alveoli [tiny air sacs] of the lungs and cause the taste you experience with intense workouts," he adds.

Also, if you're training and inhaling forcefully, especially while exercising in cold weather, Dr. Nazarian says there could be irritated areas in the mucous membranes of your mouth, nose and throat, causing a metallic taste or the taste of blood.

​Read more:​ Is It OK to Run Outside in the Cold?

If you take good care of your dental health and general health regularly and you have no chronic or acute conditions, Dr. Nazarian says there's no need to be worried. To help reduce the likelihood of having a blood taste in your mouth, he recommends resting more regularly and decreasing the intensity of your workouts.

An occasional metallic taste in your mouth is not necessarily something you need to contact your doctor about right away, but if it increases in frequency or you find that you're spitting blood after exercise, it's time to make an appointment. "If this issue is causing pain, discomfort, visible blood in the mouth or nose or a change in any health condition, contact your health care provider, especially if you have any cardiovascular or respiratory illnesses," advises Dr. Nazarian.

Moreover, the Cleveland Clinic says that a metallic taste in your mouth, while not common, could be a red flag for liver or kidney problems, certain cancers or undiagnosed diabetes.

As always, if you're experiencing any unusual symptoms during or after exercise, it's always a good idea to contact your doctor, who can help you determine if the bad taste in your mouth is cause for concern.

​Read more:​ Here's Exactly What You Need to Do After Every Single Workout