Why Do Runners Spit? (Dehydration, Drainage, and Good Etiquette)

If you’ve ever sprinted past a loogie-hocking marathoner, you may be wondering, “Why do runners spit?”

Runners spit because dehydration can cause saliva to thicken, causing build-up in the runner’s mouth and mixing with mucus. This mixture can be uncomfortable and cause runners to expel it through spitting. To reduce the effect, stay hydrated, clear your airways before running, or chew gum while running to encourage saliva production.

Continue reading below to learn more about why runners spit. 

Why do you spit a lot when running?

You’re nearly finished with your final 5k of the week, and every muscle in your body is screaming for oxygen. 

As you begin to ramp up for the final stretch, you notice a runner moving half your speed a couple of meters ahead of you. Determined to finish as soon as possible, you shout to him, “On your left!” However, just as you start to pass him, you hear an ungodly, guttural noise and, in slow motion, watch in horror as the runner turns to spit a yellowy goo right in your direction! 

Unfortunately, the urge to spit while running is a common one, and it can typically be explained by a few other common side effects of running, such as dehydration, excess drainage from your sinuses, or simply a disgusting habit.

Has this ever happened to you?

Let’s dive a little deeper to find out why runners spit while running. Here are three main reasons for the excessive spitting:

• Dehydration
• Drainage
• Habit

Dehydration

The number one reason runners spit is because of the effects of dehydration.

Running produces large amounts of sweat. When the body expels the amount of water that it does when participating in aerobic exercise, it causes other areas of the body to not receive the usual amounts of H2O that they’re used to receiving. This is true for the mouth, which usually receives a continual supply of water in the form of saliva.

When the body doesn’t pump the typical amounts of water to the mouth, saliva becomes thick and difficult to swallow. This causes runners to attempt to expel it by spitting. 

Drainage

Another reason runners often spit is due to mucus drainage from the nasal cavity.

When running, the constant gravitational pulling that occurs with the pounding of each foot strike can cause mucus to run down into the mouth. This will prompt runners to attempt to expel the substance by spitting. 

Mucus is one of the body’s defense mechanisms against allergens and harmful particles in the air. It blocks different bodily invaders by trapping them in a sticky mess that lines the nostrils. 

However, when the body is fighting allergens or infections, it sometimes produces excess mucus that can get stuck in the nasal passages. 

Habit

Athletes from many sports have made a habit out of spitting. The most famous of which is baseball. Of course, baseball players often spit at the prompting of large amounts of chewing tobacco. 

For some, spitting is habitual when outdoors. The effects of any type of exercise or movement can change the environment in the mouth, either by drying it out or by collecting excess spit. 

Nonetheless, spitting is common in sports, and some runners may have simply picked up the habit somewhere along the way.

Should you just swallow your spit when running?

Swallowing your spit actually produces a lubricating effect on the esophagus and the stomach that protects you from acid reflux and other harmful acids used in the digestion process.

This does not change when running, although you will want to be careful that the swallowing of excess spit doesn’t produce a choking hazard. 

When spit becomes dehydrated, it can become more difficult to swallow and may interrupt regular breathing patterns when running. 

Does spitting dehydrate you?

Dehydration is mostly caused by excessive sweating.

Spitting may contribute to dehydration, but the effects will be minor. However, the immediate effects of spitting may create the feeling of a dry mouth, which can be very unpleasant.

Spitting itself is such a minor expulsion of water from the body that it is unlikely to account for the complete dehydration of a runner.

Why does my saliva get sticky when I run?

Saliva begins to thicken when you run because of dehydration. When you are dehydrated, your body does not produce enough fluids to replace those you are losing. 

When participating in aerobic exercise, you will begin to sweat. This means your body will purge the fluids it contains to the outer layer of the skin in an effort to cool you off. When this process happens over a long period of time, the body will begin to become dehydrated. 

The water that your body would normally use to produce spit is now being redirected to pores in the skin to cool your body off. This is why saliva becomes thicker and more sticky when you run. 

Why do I sometimes taste blood when I run?

If you find yourself tasting blood in your saliva while running, it could be because of blood in your lungs.

The activity of running actually raises your blood pressure. When this happens, some tiny fluid sacs in your lungs may burst, releasing blood into your lungs. With every exhale, some of that blood can travel up into the mouth, giving you the taste of iron.

This is usually only experienced in trace amounts and should not greatly affect the substance of the saliva in your mouth while running. If you’re experiencing this, it’s nothing to be too worried about, but it could be an indicator of high blood pressure.

How to stop spitting when running

While there isn’t anything inherently wrong with spitting while you run, it is gross and can be a breach of etiquette in certain situations. What’s worse, the longer you keep it as a habit, the harder it will be to break it!

Here is a list of potential strategies for kicking the habit. Take a look and see if you find any of these methods appealing:

• Hydrate before your run
• Carry a water bottle
• Clear your airways
• Chew gum

Let’s check out a few ways to stop spitting while running.

Hydrate before your run

When participating in an activity like running that requires heavy breathing, the mouth can become extremely dry. This can produce the unpleasant feeling of dry mouth and can lead to thick, syrupy saliva that runners feel compelled to expel by spitting. 

Hydrating well before partaking in aerobic exercise will produce several benefits, including the production of saliva, which is needed to lubricate the mouth. 

About 2 hours before a run, you should aim to drink about 16 ounces of water, followed by an additional 6-8 ounces about 15 minutes before your run. This should allow you to train at proper hydration levels and keep you from constantly spitting during your run. 

Carry a water bottle

Many runners have found it helpful to carry their hydration with them in the form of a water bottle.

There are various types of water-toting accessories that you can purchase, ranging from flask-style canteens to backpack carriers. Some of them are incredibly easy to carry, while the use of others requires a bit of an adjustment from the runner.

Check out the following options if you find yourself considering this as an option for spit reduction:

• Nathan Handheld Quick Squeeze Bottle
• Amphipod Hydraform Handheld Bottle
• Hydrosleeve Hydration Pack

Clear your airways

Part of the problem with runners and their constant need to spit is excess mucus that flows down from the nasal cavity due to the force of gravity exerted on the runner with each foot strike. 

Before starting your run, clear your airways by blowing your nose thoroughly and coughing up and spitting out any phlegm blocking your airways.

Removing the excess mucus before your run can help eliminate any unpleasant drainage later on.

Chew gum

Finally, another strategy for reducing the amount of spitting on your runs is to chew gum.

Chewing gum produces natural saliva and can help keep your mouth hydrated during long runs. The only caveat here is that it can be quite dangerous to chew gum while constantly inhaling and exhaling. 

If you do attempt to do this, you must be aware of the choking hazard and remain focused on the fact that you have gum in your mouth throughout the run.