Why Do I Taste Blood When I Run?

Running can cause a lot of body reactions. Anything from sweat, to a racing heart, burning muscles and occasionally blood taste in mouth, which is an odd reaction that may occur during a very intense run and cause you to become confused. You won't see any blood, but surely may taste it. This article will explain why this happens, and if you need to be concerned.

Why Do I Taste Blood When I Run?

Intense exercise can cause red blood cells to break down faster and move into the air sacs in the lungs, which may cause you to taste blood during periods of exercise or when you're running at a fast pace. You may also be tasting a metallic taste in your mouth that isn't blood, but drainage from something going on in your mouth. Certain medications can also cause a metallic taste in your mouth. Other causes include:

1. Sinus Conditions

Running when you have a sinus infection or clogged sinuses can increase the pressure and possibly cause a blood vessel to rupture. This may cause blood to enter the sinus drainage that enters the back of the throat, causing you to taste blood.

2. Cold Dry Weather

Cold, dry air can cause the tender membranes in the nose to become thinner and break open easier. When you run you breathe more and this can dry out the inside of the nose. When the membranes become too thin they can burst and cause blood to drip into the back of the throat, causing that blood taste in your mouth.

3. Asthma

Why do I taste blood when I run? You ask. If you have asthma and you run either for exercise or sport, you may have this happen due to the onset of an exercise induced asthma attack. This is actually a metallic taste in the mucus produced by the lungs.

4. Tooth Decay

A badly infected tooth may cause drainage or even blood to leak into the mouth. This can happen at any time, but may be worse during exercise since the heart is pumping harder during that time. This causes any fluids to drain from the body faster including, drainage from a tooth.

5. Salivary Duct Blockage

Your salivary ducts make the saliva you need for digestion of food and keeping your oral areas moist. When a salivary duct becomes blocked it can release toxins and infection into the mouth. These toxins can cause a bad taste in the mouth that may taste like blood. If you are now wondering, "Why do I taste blood when I run?" and it is due to a blocked salivary gland you may actually be tasting drainage from the gland.

6. Intensive Workout

An intense workout may cause blood vessels to burst. It can happen with a hard run, lifting heavy weights, or anything else that causes you to tense up. With an intensive workout/run, you may burst blood vessels in the mouth and taste blood. It may be a sign that you are overworking your body.

7. Dehydration

If you don't drink enough fluids prior to or during your run, you may get dehydrated. This can cause different tastes in your mouth, especially a metallic taste like blood. Try not to confuse this with just having a dry mouth, dehydration is much more serious. As a matter of fact, by the time you feel a dry mouth with dehydration, your body is already way too low on fluids. When you have that taste and your mouth is dry, drink fluids anyway just to be safe.

8. Pulmonary Edema with Exercise

While controversial, there is a thought that during exercise the pressure in your lung air sacs increases with increased breathing and heart rate. This may cause the sacs to swell and leak fluid, causing you to taste something like blood in your mouth. Researchers are still looking into this condition.

Should You Worry?

If you ask, "Why do I taste blood when I run?" and it is happening often, you may need to make an appointment with your doctor to make sure it is nothing serious. It actually isn't anything to worry about if it only happens once in a great while or even only one time. You should contact your doctor if the problem is continuous and you have other symptoms like:

  • Fever over 100.4℉
  • Mouth, nose, tooth, or ear pain
  • Feeling generally unwell
  • Fatigue
  • Excessive drainage from the mouth

Is There a Way to Prevent It?

If you taste blood when you run occasionally and you know it isn't serious, there are a few things you can do to help prevent this from happening. You will want to make sure you prepare yourself for your run properly, not overexert yourself during your run, and listen to your body if you need a break. Here are some helpful tips:


  • Warm up your body before exercise.
  • Bundle up if you plan on running in the cold (face mask, scarf over mouth and nose).
  • Pre-hydrate your body with plenty of fluids.

During Your Run

  • Pace yourself. Try not to overexert or push yourself over your limits.
  • Drink fluids often during your run to keep hydrated and rinse your mouth.
  • Slow down or stop if you feel yourself getting overtired.
  • Try chewing gum to cover any tastes in your mouth.

After Your Run

  • Do cool down exercises to help your body recover.
  • Give your mouth a good rinse with water to help remove drainage.
  • Try using mouthwash to freshen the taste in your mouth.
  • If you run daily and you taste blood in your mouth, try taking a day off in between.
  • If the taste continues after all the above measures, give your doctor a call to make sure something serious isn't going on.
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