Why would a person smell of ammonia?

September 28, 2025 •

4 min read

The smell of ammonia can indicate a metabolic shift within the body, sometimes caused by everyday factors, but potentially signaling more serious health issues. Understanding why would a person smell of ammonia? is the first step toward addressing the root cause, whether it's a simple dietary change or a visit to your doctor.

Quick Summary

An ammonia smell can be a sign that your body is breaking down protein for energy due to a lack of carbohydrates, often caused by diet or strenuous exercise. It can also point to issues with the kidneys or liver, which process ammonia, and is intensified by dehydration. A persistent odor warrants medical evaluation.

Key Points

Dietary Causes: High-protein, low-carb diets (like keto) can trigger an ammonia odor as the body metabolizes protein for energy, releasing excess ammonia through sweat and urine.
Exercise Intensity: Pushing your limits during intense or prolonged workouts, especially when glycogen stores are low, can cause your body to burn protein, leading to an ammonia smell in sweat.
Dehydration Magnifies Odor: Insufficient water intake concentrates waste products in sweat and urine, making any ammonia odor more pronounced.
Kidney and Liver Health: A persistent ammonia smell can indicate impaired function of the kidneys (uremia) or liver (hyperammonemia), which are responsible for processing and filtering ammonia.
Signs of Medical Concern: If the ammonia smell is not explained by diet or exercise, or is accompanied by symptoms like fatigue, nausea, or confusion, it's essential to consult a healthcare provider.

The Metabolic Breakdown: When Your Body Burns Protein

At its core, an ammonia odor is a byproduct of protein metabolism. Our bodies prefer to use carbohydrates for energy. When carbohydrates are scarce, the body turns to its secondary fuel source: protein. This process breaks down amino acids, releasing nitrogen. The liver then converts this nitrogen into ammonia, which is usually processed further and excreted in the urine. However, if ammonia is produced faster than the liver can convert it or the kidneys can filter it, the excess is released through sweat, causing a noticeable ammonia smell.

Diet: High-Protein, Low-Carbohydrate Plans

Individuals following high-protein, low-carbohydrate diets, such as the ketogenic (keto) diet, are particularly susceptible to this issue. By design, these diets restrict carbohydrate intake, forcing the body into a state of ketosis where it burns fat and protein for fuel. The increased protein breakdown leads to a rise in ammonia production. While often temporary as the body adapts, this metabolic shift is a primary cause of ammonia-smelling sweat and breath in otherwise healthy individuals.

Exercise: Pushing Your Limits

Intense or prolonged exercise without adequate fueling can also trigger this effect. When your glycogen stores (stored carbohydrates) are depleted during a long run or strenuous workout, your body begins catabolizing muscle protein for energy. The resulting ammonia is then released through sweat. A strong ammonia odor at the end of a workout is a signal that your body has run out of its preferred fuel source and is tapping into protein reserves. Increasing carbohydrate intake before and during exercise can help prevent this.

The Role of Hydration

Dehydration is a simple but significant factor that can exacerbate an ammonia odor. When you don't drink enough water, your sweat becomes more concentrated with waste products. Just as dehydrated urine is darker and more pungent, dehydrated sweat carries a stronger smell. Staying properly hydrated helps dilute these compounds, making any odor less noticeable and aiding your kidneys in their detoxification processes.

When an Ammonia Smell Signals Medical Concern

While often tied to dietary and exercise habits, a persistent or strong ammonia smell from the breath, sweat, or urine can be a red flag for underlying medical conditions. If lifestyle changes don't resolve the odor, or if it's accompanied by other symptoms, seeking medical attention is crucial.

Kidney Disease

When the kidneys are not functioning properly, they cannot efficiently remove urea, a waste product that contains ammonia, from the bloodstream. This leads to a buildup of nitrogenous waste, a condition called uremia. The excess urea can then be released through sweat and the breath, causing a distinct ammonia or urine-like odor. Advanced kidney disease can cause a specific type of bad breath known as "uremic fetor."

Liver Disease

The liver plays a vital role in converting ammonia into urea. If liver function is impaired due to disease, ammonia can accumulate in the blood (hyperammonemia). This can lead to a range of symptoms, including an ammonia odor on the breath. In severe cases, it can also cause hepatic encephalopathy, a decline in brain function that occurs as a result of liver disease.

Diabetes

Diabetic ketoacidosis (DKA) is a serious complication of diabetes that occurs when the body produces excessive ketones. While ketones are sometimes associated with a sweet or fruity breath, a severe buildup can create a different, more pungent odor. DKA is a medical emergency that requires immediate treatment.

A Quick Comparison of Common Causes


Cause	Odor Location	Associated Symptoms	Recommended Action
High-Protein Diet	Sweat, Breath	Can include keto flu symptoms; usually temporary	Increase carbohydrate intake, stay hydrated
Intense Exercise	Sweat	Fatigue, muscle soreness	Adjust pre-workout carb fueling
Dehydration	Sweat, Urine	Thirst, dark urine, fatigue	Increase water intake
Kidney Disease	Breath, Sweat, Urine	Fatigue, nausea, confusion	Consult a doctor for evaluation
Liver Disease	Breath, Sweat	Jaundice, fatigue, confusion	Consult a doctor urgently
Diabetic Ketoacidosis	Breath	Excessive thirst, urination, confusion, vomiting	Seek immediate medical attention

Management and Prevention Tips

Optimize Your Diet: Balance your macronutrient intake. Ensure you're consuming enough carbohydrates to fuel your body, especially if you lead an active lifestyle or are on a low-carb diet. This prevents your body from resorting to protein for energy.
Stay Hydrated: Drink plenty of water throughout the day. This simple step helps dilute waste products in your sweat and urine, minimizing the concentration of ammonia.
Adjust Exercise Fueling: For intense or long workouts, consider having a carbohydrate-rich snack beforehand, such as a banana or energy bar. This provides readily available fuel, sparing your protein stores.
Maintain Good Hygiene: Regular showering with antibacterial soap can help control bacteria on the skin that can contribute to odor. Wearing breathable fabrics can also reduce sweat buildup.
Monitor for Other Symptoms: Pay close attention to any accompanying symptoms, such as fatigue, confusion, or changes in urination. These can be important clues for a doctor.

When to Consult a Healthcare Professional

An ammonia smell that is persistent, not explained by diet or exercise changes, or is accompanied by other symptoms like nausea, confusion, itching, or changes in urine color, warrants a doctor's visit. A healthcare provider can run tests to check kidney and liver function and rule out more serious underlying conditions. Don't hesitate to seek professional medical advice for your peace of mind and health.

For more detailed information on managing body odor related to specific health conditions, consult a trusted health resource like the Mayo Clinic.

Conclusion

An ammonia smell can be a surprising and sometimes concerning change in body odor. From the metabolic shifts induced by low-carb diets and intense exercise to more serious implications related to kidney or liver function, the causes vary. By understanding the potential reasons and taking proactive steps—such as staying hydrated and adjusting your diet—you can often resolve the issue. However, always prioritize consulting a healthcare provider if the odor is persistent or accompanied by other worrying symptoms, ensuring any underlying health concerns are properly addressed.

Frequently Asked Questions

Yes, dehydration can cause a noticeable ammonia smell in both sweat and urine. When you are dehydrated, waste products like urea and ammonia are more concentrated in your bodily fluids, making their odor stronger.

No, not always. The ammonia smell is often a temporary side effect of the initial adaptation phase of a ketogenic diet, particularly if protein intake is too high. As your body becomes more efficient at using fat for fuel, the odor often subsides.

Ammonia breath can be a sign of a high-protein diet or dehydration. In more serious cases, it can indicate a problem with your kidneys or liver, as these organs are responsible for processing ammonia from the bloodstream.

If the ammonia smell only occurs after a long or intense workout, it is likely due to your body burning protein for energy. It's often not a cause for immediate concern, but you should consider increasing your carbohydrate intake before exercising to provide better fuel.

Uremic fetor is a strong, unpleasant breath odor often described as smelling like ammonia or urine. It is a symptom of advanced kidney disease, where the kidneys cannot properly filter urea from the blood, causing it to build up.

Yes, in healthy individuals, consuming too much protein can sometimes overwhelm the liver and kidneys' ability to process the resulting ammonia efficiently, leading to a temporary ammonia smell in sweat or urine.

An ammonia smell, particularly on the breath, that is accompanied by confusion, excessive thirst and urination, vomiting, or significant fatigue could be a sign of a serious medical condition like diabetic ketoacidosis or advanced liver failure. Seek immediate medical attention if these symptoms appear.