Thick Saliva When Running (4 Reasons Why)

Thick Saliva When Running

Last week, for the first time in a while, I went on a long run. As a result, I had a lot of saliva build-up and had to spit more times than usual. I started wondering, why do I sometimes have thick saliva when running?

After doing some research, I found that the main causes of thick saliva when running are from dehydration, a stuffy nose from sickness or allergies, cold air, and your fitness level. A dry mouth is a sign of dehydration, your saliva thickens to compensate for this. Stuffy noses from sickness or allergies will cause your body to produce more mucus which can result in thicker saliva. Mucus in the mouth is also produced during cold weather, as it acts as a humidifier to the cold dry air before it reaches your lungs. Finally, an increase in saliva production is more apparent at the start of your run and maybe impacted by how fit you are. In the remainder of this article, we’ll go into more detail on the different causes of thick saliva when running.

Why Dehydration Causes Thick Saliva When Running?

Dehydration is a result of lost fluid from your body. Essentially if you are not replenishing your body with fluids as fast as you are losing them, you will become dehydrated.

Fluid loss from your body is greatly increased when you are sick, when you are exerting yourself physically and in warmer climates.

For example when you are running (exerting yourself physically), your body temperature is significantly warmer than usual. Your body naturally tries to cool itself down by sweating.

If you aren’t regularly replenishing the lost fluids from your body sweating, it can lead to you being dehydrated.

There are several symptoms of dehydration, and they are typically categorized by mild and severe (consult a medical professional immediately if you are unsure of your symptoms).

One mild symptom is a dry mouth, which is a result of your salivary glands not producing enough saliva. Your saliva then becomes thicker as there is a lack of moisture in it.

How Can A Stuffy Nose Cause Thick Saliva When Running?

The main two causes of stuffy noses are from being sick, or from allergies.

When you are sick or being impacted by seasonal allergies, typically your body is producing more mucus than usual.

Your body will struggle to get a full breath of air through your nose as it becomes stuffed and fills with mucus. By default, your brain quickly solves this problem by breathing through your mouth.

As you are running with your mouth wide open and trying to breathe in as much oxygen as possible, your mouth begins to dry out. Your saliva then begins to thicken as it doesn’t have enough moisture in it.

As previously discussed, this is also a sign of dehydration when running. 

Why Does Cold Air Lead To Thick Saliva When Running?

Cold air is generally less humid than warm air. What does this mean?

Humidity is the measure of water vapor or moisture in the air. Thus, cold air has less water vapor in it.

As you breathe in cold air, your body works hard to humidify it and warm it up to a temperature that won’t be damaging to your lungs. Your nose and throat help humidify cold air by providing it with moisture.

As your body begins to use moisture from your mouth to humidify the air, your saliva beings to have less liquid in it. The lack of liquid results in your saliva becoming thick, and as some would describe, sticky. 

How Do Fitness Levels Impact Thick Saliva When Running?

As you initially start running, you may produce more saliva. This is because your body is trying to compensate for increased breathing through your mouth.

However, as your run progresses, you become more dehydrated, your mouth begins to dry and saliva starts to lack moisture, becoming sticky.

Runners who are more fit, have better control of their breathing, and are well hydrated might not notice thick saliva until later on in their run.

Runners who are less fit and are breathing heavily will typically notice their mouth becoming dry and thick saliva forming at an earlier stage in their run.

How Can I Prevent Thick Saliva When Running?

There are several ways to prevent thick saliva while running. If you struggle with seasonal allergies, be sure to take allergy medication before running, or if they are too bad, stick to the treadmill inside.

Bring tissues with you on your run if you have a cold or are getting over one. Make quick stops throughout your run to blow your nose.

This will help you breathe through your nose, and reduce thick saliva build-up.

Recommended Products

Check-out the list of the products we recommend to help keep you hydrated throughout your day.

However, the simplest way and most commonly discussed point in this article is staying hydrated.

As your body is exerting itself physically, it is crucial to replenish these lost fluids. It is important to not only hydrate before running, but also during and after a run. 

Hydrating Before A Run

Regardless of whether or not you are running today, you should be staying hydrated.

Many people drink water throughout the day, but only when they are feeling thirsty. Furthermore, most people couldn’t tell you how much water they drink a day.

A hydration plan and a reusable water bottle are the simplest of ways to keep you regularly drinking water. 

It is worth investing in a good daily water bottle that will keep you on track with your hydration goals. If you struggle with remembering to drink water, consider buying a water bottle that tracks how much you drink, or one that has a built in reminder alarm

Hydrating During A Run

It is important you are replenishing fluids while you are running and exerting yourself physically.

However, it is awkward to carry a water bottle while you run. A great alternative is a hydration belt or a hydration vest. Typically you can store a few small water bottles, and even a gel pack or two.

Belts have adjustable straps to fit the majority of body sizes. Adjustable straps also ensure the belt is secure to your waist, helping to minimize the bounce while running.

Vests have adjustable chest straps and sit securely over your shoulders to minimize movement while exercising.

Hydrating After A Run

Water is always a great choice for hydrating. However, there are alternatives that are designed to actually hydrate you faster and more efficiently than water alone.

If you are feeling more dehydrated than usual after a long run, consider picking up one of the many hydration drinks for runners. They are supplements that are packed with electrolytes, vitamins, and minerals that can be added to water.

Various different kinds are available, many are fruit flavored and taste great. If you have ever completed an organized race (half-marathon, marathon, etc.) you’ll notice more often than not the organizers are handing these types of drinks out after you cross the finish line.


The idea for this article came to me last week after I went on a long run. I haven’t been on a long run in a few weeks, temperatures are starting to drop as winter is around the corner, and I began to wonder: why do I sometimes have thick saliva when running? 

Throughout this article, we answered this important question that many runners experience. In the most general terms, saliva thickens when there is a lack of moisture in your mouth.

The primary cause of this is dehydration, however stuffy noses, and breathing in cold air can also help expedite this problem. Similarly, your fitness level, or lack thereof, can also play a role in why you sometimes have thick saliva when running.

Additionally, we discussed the importance of not only hydrating before a run, but also replenishing lost fluids during and after a run. The best ways to keep your hydration goals on track are to:

  1. purchase a reusable water bottle for use throughout the day
  2. consider using a hydration belt while running, allowing for ongoing replenishment
  3. have an electrolyte and vitamin-packed hydration drink after your run to help rehydrate you faster and more efficiently

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Facts for this article are referenced from credible sources. For further information, please read these referenced articles from the following organizations:

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