Why Do I Taste Blood When I Run? 6 Causes + Solutions

Some runners report a blood-like or metallic taste whilst running. We'll look at possible causes, whether you should be worried about it, and how to prevent it.

Some odd sensations can be experienced when you run. You can feel lightheaded or dizzy; itchy, and during hard workouts, you can feel an uncomfortable, burning sensation in your legs.

It’s also possible to have strange taste sensations when you run.

In fact, a surprising number of runners may sometimes have the unpleasant experience of having a metallic taste or taste of blood in their mouth while running.

It can also occur during other types of non-running workouts, whether it be aerobic exercise or strength-based training.

A person covering their mouth.

Why Do I Taste Blood When I Run?

It can be as unsettling as it is unpleasant to experience a bloody taste while running or doing any other type of intense exercise, but most health experts say it’s a fairly common phenomenon amongst runners.

Many runners who do experience the taste of blood in their mouth while running don’t have visible blood in the saliva, should they spit. 

The metallic taste is associated with the iron content in blood, so usually, when you’re tasting a metallic flavor, it’s a sign that there’s some amount of bleeding going in your mouth or respiratory passages.

Here are a few of the common causes of the taste of blood during intense exercise:

A person hunched over, breathing hard.

#1: Breathing Hard

It might just be that huffing and puffing you’re doing during your speed workout that is the reason you’re tasting blood in your mouth.

During intense exercise, fluid accumulates in the small air sacs of the lungs called the alveoli, in what is termed mild pulmonary edema.

Additionally, exercise increases pulmonary pressure, which can cause red blood cells to leak into the alveoli, the sites in the lungs where air and gas exchange take place.1What Causes a Metallic Taste In Your Mouth? (n.d.). Cleveland Clinic. https://health.clevelandclinic.org/common-causes-for-metallic-taste-in-your-mouth

The abnormally-located red blood cells in the alveoli can then burst because of this increased blood pressure and pulmonary during exercise.

When they burst, you will be able to taste the metallic taste of blood as you forcefully inhale and exhale.

The heavier you breathe, the more pressure in your lungs, so the more intense the taste may be. 

#2: Irritated Mucous Membranes 

Particularly when you exercise in cold weather, at high altitude, or in particularly dry air, the mucous membranes in your nose, mouth, and lungs can become irritated.

Again, this is exacerbated the more forcefully you breathe, so if you’re doing a hard run outside in the winter, your delicate mucous membranes can get damaged.

This damage can lead to rupturing of the tiny capillaries (blood vessels) in your airway, mouth, nose, and lungs, which can lead to a metallic taste in your mouth as you run.

A person holding their chest.

#3: Heartburn

Heartburn, GERD, or acid reflux can cause a metallic taste in the mouth from the acid coming up from the GI tract.2Information, N. C. for B., Pike, U. S. N. L. of M. 8600 R., MD, B., & Usa, 20894. (2018). Heartburn and GERD: Overview. In www.ncbi.nlm.nih.gov. Institute for Quality and Efficiency in Health Care (IQWiG). https://www.ncbi.nlm.nih.gov/books/NBK279254/

During exercise, this may be exacerbated due to increased intraabdominal pressure and exertion.

Additionally, if you run too soon after eating, you’re more likely to experience acid reflux while running.

The metallic taste will likely be accompanied by bloating, a feeling of indigestion, and possible gas or belching.

Additionally, in relation to cause #2, the mucous membranes of a throat that is sensitive or damaged from GERD are more likely to be irritated from an intense workout, meaning that these two causes can sometimes be linked.

A person running.

#4: An Oral Infection

It’s possible that poor dental health can contribute to that metallic taste in your mouth during exercise. 

According to the Cleveland Clinic, poor oral hygiene and dental health, such as periodontitis, gingivitis, cavities, tooth decay, and tooth infections, may contribute to a metallic taste in your mouth.3What Causes a Metallic Taste In Your Mouth? (n.d.). Cleveland Clinic. https://health.clevelandclinic.org/common-causes-for-metallic-taste-in-your-mouth

Depending on the severity of your oral issue and your sensitivity to taste, these dental conditions can potentially cause a metallic taste even when you aren’t running or working out.

However, the intensity of the taste will likely increase during exercise, and some people won’t notice any taste abnormalities at all until they are doing high-intensity exercise.

This is because physical activity increases circulation, so any existing tooth decay or blockage of salivary glands can cause you to taste blood once you get the blood moving more.

A person smelling their breath.

#5: Salivary Stones

One potential cause of a metallic taste in the mouth during exercise is salivary stones.

Much like kidney stones or gallstones, salivary stones are stones that accumulate in the salivary ducts, causing a blockage or potentially even an infection.4Salivary gland stones. (2017, October 19). Nhs.uk. https://www.nhs.uk/conditions/salivary-gland-stones/

Exercising increases circulation, saliva production, and the rate and force of breathing.

This gets saliva and blood flowing, so if there’s an infected or blocked salivary duct, you may experience a foul, metallic taste from the infected duct as you run.

#6: Burning Mouth Syndrome

In addition to dental issues, something called “burning mouth syndrome” can cause you to taste blood in your mouth when running.

Although not particularly common, this medical condition is marked by a chronic burning feeling in the mouth, along with sensations like a bitter or metallic taste.5Burning Mouth Syndrome | National Institute of Dental and Craniofacial Research. (n.d.). Www.nidcr.nih.gov. https://www.nidcr.nih.gov/health-info/burning-mouth#:~:text=7%20%2D%20Related%20Publications-

A person covering their mouth wondering why do I taste blood when I run?

Is It Bad to Taste Blood In Your Mouth While Running?

In most cases, tasting blood in your mouth while running is unpleasant but nothing to be worried about, particularly if you’re in good health and practice good oral hygiene.

However, there are cases where a metallic taste in your mouth should signal you to seek medical attention.

For example, if the metallic taste lingers after exercise throughout other parts of the day, it could be indicative of a different underlying cause. 

Similarly, if the taste of blood while running is accompanied by other symptoms, such as tooth pain, you should seek dental consultation.

Finally, if you’re also spitting visible blood while running or after you have finished your workout or otherwise don’t feel well, it’s a good idea to check in with your doctor about other potential causes.

Although it’s not uncommon to taste blood in your mouth during vigorous exercise, it can also (though not often) be indicative of more serious underlying issues like liver or kidney problems, diabetes, cardiovascular issues, and potentially certain cancers or undiagnosed diabetes.

Therefore, if you do have concerns or a history of other chronic health conditions, it’s a good idea to bring it up with your doctor.

A person covering their mouth.

How to Reduce the Likelihood Of Tasting Blood In Your Mouth During Exercise

Aside from seeking oral healthcare for potential dental caries or infections, the following can help reduce the risk of getting a metallic taste in your mouth during exercise:

Slow Down

In most cases, tasting blood in your mouth while running is a byproduct of breathing hard.

If you ease up on the intensity of your workout, you will breathe less forcefully. This, in turn, will reduce the pressure in the tiny air sacs of the lungs, reducing the leakage of red blood cells and the subsequent lysis of the cells.

Wear a Buff

If you are running in the cold, wear a buff or mask over your nose and mouth to help warm the air before it hits your airways.

Focus on breathing through your nose rather than your mouth because the nasal passages warm, humidify, and filter the air while your mouth lacks these abilities.

Nasal breathing will help reduce the irritation of the mucous membranes, which can then prevent damage and microscopic blood leakage.

Overall, tasting blood in your mouth while running is usually a benign byproduct of exercising intensely, but if you’re concerned about it, try easing up on your pace to see if that gets rid of it.

If so, you can feel more confident that your body is just working hard, but don’t be afraid to bring it up with your doctor if you have concerns.

To practice nasal breathing as a way of reducing this feeling, check out our guide.

A dog wearing a buff.


Photo of author
Amber Sayer is a Fitness, Nutrition, and Wellness Writer and Editor, as well as a NASM-Certified Nutrition Coach and UESCA-certified running, endurance nutrition, and triathlon coach. She holds two Masters Degrees—one in Exercise Science and one in Prosthetics and Orthotics. As a Certified Personal Trainer and running coach for 12 years, Amber enjoys staying active and helping others do so as well. In her free time, she likes running, cycling, cooking, and tackling any type of puzzle.

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