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Why Does My Sweat Smell Like Ammonia After A Workout?

Sweating is a thermoregulatory mechanism to ensure that our core body temperature can return to normal temperatures when it is elevated during exercise, fevers, or in the heat.

But, what does it mean if your sweat smells like ammonia or if your sweat smells like urine?

If you find yourself asking, why does my sweat smell like ammonia, keep reading to find out!

In this guide, we will cover: 

  • What is Ammonia?
  • Why Does My Sweat Smell Like Ammonia?

Let’s dive in! 

A person smelling their sweat.

What is Ammonia?

Before we look at the reasons why you may have an ammonia odor in your sweat, let’s discuss what ammonia is.

Ammonia is a nitrogenous compound with the chemical formula NH3, which means that an ammonia molecule has one nitrogen atom bonded to three hydrogen atoms.

Ammonia is a colorless gas but not an odorless gas; it has a pronounced odor that can smell somewhat like foul urine or foul-smelling sweat.

This is why people ask questions like: “Why does my pee smell like ammonia, what does ammonia urine mean, or why does my sweat smell like ammonia?”

Ammonia is a naturally occurring compound found in the air, soil, water, plants, animals, and the human body.

Our bodies produce ammonia when proteins are broken down into their constituent amino acids, which are the building blocks of larger protein molecules that are held together with peptide bonds.

A person with bad-smelling swaet on a couch with nose plugs on.

When you eat protein-rich foods or when your body metabolizes your own muscle tissue, these larger protein molecules are broken down into amino acids.

Amino acids that are yielded from dietary proteins, muscle protein breakdown, or the degradation of other biological cells, tissues, and proteins provide usable amino acids that can then be formed into different proteins or used for energy in cases of low energy availability or starvation.

However, there are also metabolic byproducts or metabolic waste that are created through protein digestion.

Ammonia is one of the main waste products of protein digestion or protein breakdown to amino acids.

The liver, which is one of the foremost detoxifying organs in the body, can convert ammonia to urea.

Urea is then excreted by the body by passing through the kidneys and leaving the body in urine or excreted through eccrine and apocrine sweat glands when you sweat.

A person holding their nose because of a bad smell.

Because ammonia has a smell that is sometimes likened to very concentrated urine, some people who are experiencing sweat that smells like ammonia conflate and ammonia odor sweat to sweat that smells like urine. 

For this reason, a common question is: “Why does my sweat smell like urine, or why does my sweat smell like pee?“ 

Ultimately, the exact causes of your sweat smelling like urine are those that we will discuss as reasons that your sweat smells like ammonia since ammonia has a foul urine-like odor.

Why Does My Sweat Smell Like Ammonia?

There are various causes that can make sweat smell like ammonia, such as the diet you are following, the type or intensity of the exercise you are doing, or underlying health conditions such as kidney disease.

Let’s look at some of the most common reasons why your sweat smells like ammonia:

A variety of protein rich foods such as chicken and eggs.

#1: A High-Protein Diet

What you eat can affect how your sweat smells.

In particular, following a high-protein diet can cause your sweat to smell like ammonia, as can a low-carb diet, particularly if you are in a caloric deficit and losing weight.

Stored carbohydrates (glycogen) and circulating blood glucose are the preferred fuel sources for muscles and certain cells and tissues of the body, such as the brain and red blood cells.

However, if your body has insufficient glycogen stores due to the following reasons, your body will have to break down muscle protein for energy in addition to the dietary protein digestion already taking place.

  • Following a low-carb diet
  • Performing long endurance exercise
  • Exercising in the fasted state
  • Not eating enough calories on an extreme weight-loss diet
  • Following a particularly high-protein diet and not eating carbs regularly or in sufficient quantities

This can cause excessive ammonia production and accumulation.

When too much ammonia is produced from the breakdown of protein into amino acids, the rate of ammonia production may exceed the capacity of the liver to process ammonia into urea.

As a result, your urine and sweat will have a higher concentration of ammonia, thus causing sweat that smells like ammonia or pee.

A person dehydrated on the desert ground.

#2: Dehydration

Another cause of sweat smelling like ammonia is dehydration.

As with urine, when you are dehydrated, the solutes, or particles that your body excretes in the sweat or urine, are more concentrated because there is less liquid volume to dilute these particles.

If you aren’t drinking enough water and you are dehydrated, your body is still going to be trying to get rid of ammonia in sweat, but because your body will need to conserve water due to dehydration, the fluid volume of sweat will decrease.

This will cause the ammonia sweat smell to be more pronounced, just as ammonia urine smell is worse when your urine is darker yellow, and you are dehydrated (because the urine has less water to dilute the foul odor of ammonia, too).

A person sitting on a gym floor exhausted from exercise.

#3: Exercise

Of course, the more intensely you exercise, the more you will sweat.

Therefore, there’s a good chance that if you are excreting a high amount of ammonia, foul-smelling sweat or sweat smelling like ammonia will be most noticeable after working out.

Numerous studies have indeed confirmed that vigorous exercise seems to increase the ammonia odor in sweat.

However, an older study found that while the amount of ammonia excreted in sweat is high during exercise, the concentration of ammonia in sweat decreases over the 24-hour period following a workout.

This means that you might find that your sweat smells like ammonia during exercise and after working out but that as the day progresses, even if you get sweaty later on doing outdoor work in the sun (that isn’t necessarily a high-intensity workout), your sweat won’t have the same off-putting ammonia funk it had right after your workout.

Plus, as mentioned, ammonia is primarily produced when the body breaks down proteins.

If you are doing long endurance workouts or exercising first thing in the morning before eating, a higher percentage of the calories needed to fuel your workout will actually come from metabolizing your own muscle tissue.

A person on an exercise bike.

As your muscle protein is broken down into amino acids for energy, ammonia is produced.

With intense or long workouts, you might be producing too much ammonia for the liver to keep up with the conversion of ammonia to urea, which will cause your sweat to have a pronounced ammonia smell.

Again, sweat is one of the two ways in which the body gets rid of excess ammonia, which is otherwise a toxin.

This is why people often say that sweating is a good way to “detox“ your body, and it is another reason why you will likely notice ammonia-smelling sweat during hard workouts.

To the end, as discussed, a factor that can cause your sweat to smell like ammonia is dehydration.

If you are sweating a lot during exercise and not staying well hydrated before and during your workouts, you will likely notice a particularly strong ammonia sweat smell while working out.

This is yet another reason to stay on top of your hydration during exercise.

A notebook, pen and stethoscope.

#4: Health Conditions

Finally, there are certain underlying health conditions that can cause foul-smelling sweat or may cause an ammonia sweat smell.

One of the main conditions that can cause sweat smelling like ammonia during exercise is kidney disease.

The kidneys help process and excrete urea through urine. If your kidneys are not functioning optimally, this process may be hampered.

As a result, a higher concentration of ammonia and urea will be excreted through sweat to prevent the toxic buildup of ammonia and urea compounds. 

This will manifest as sweat smelling like urine or ammonia.

Uncontrolled diabetes can also potentially cause foul-smelling sweat or an ammonia sweat smell.

A doctor with a patient.

This can occur when the body is not responding appropriately to insulin, so fat and/or protein has to be broken down for energy.

Excess fat breakdown produces ketones, which can cause a fruity-smelling breath and general funk or body odor that may cause your sweat to smell bad. 

Diabetic ketoacidosis can occur if this is not resolved.

Additionally, muscle protein breakdown may increase, and again, this causes a spike in ammonia production.

If you find that your sweat smells like ammonia after workouts, you are not alone. Many people actually find themselves asking: “Why does my sweat smell like ammonia after working out?” 

However, although it is somewhat common to have ammonia-smelling sweat, sweat smelling like ammonia isn’t necessarily “normal,“ or a “good” thing.

Make sure to speak with your doctor if the issue continues or if you have concerns about the smell of your sweat.

What about salty sweat? Are you a salt sweater? For information, click here.

A salt-covered shirt on a clothesline.
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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