Is there a condition that makes you smell really bad?

September 27, 2025 •

4 min read

While most body odor is caused by bacteria breaking down sweat, a small number of people have medical conditions that cause a distinct, persistent, and unpleasant smell. Is there a condition that makes you smell really bad? Yes, there are several, and the odors are often caused by the body's inability to properly break down certain compounds.

Quick Summary

Several medical conditions can produce distinct and powerful body odors, often resulting from metabolic issues where the body cannot properly process certain substances. The specific smell can offer clues about the underlying cause, whether a genetic disorder like Trimethylaminuria, a skin condition like bromhidrosis, or issues related to liver, kidney, or diabetes.

Key Points

TMAU is a genetic disorder: Trimethylaminuria, or 'fish odor syndrome,' is a rare genetic condition where the body cannot break down the fishy-smelling compound trimethylamine.
Bacteria cause most odor: The most common cause of significant body odor, known as bromhidrosis, is the bacterial breakdown of sweat secretions, especially from apocrine glands.
Liver and kidney disease have distinct smells: Severe liver failure can cause a musty or garlicky breath (fetor hepaticus), while advanced kidney failure leads to an ammonia-like breath (uremic fetor).
Fruity breath can signal a medical emergency: A fruity, sweet, or acetone-like smell on the breath can be a symptom of diabetic ketoacidosis (DKA), a life-threatening complication of diabetes.
Diagnosis is key: If you experience persistent or unusual body odor, consulting a healthcare provider is crucial for a proper diagnosis and management plan, as the cause can be metabolic, genetic, or related to organ function.
Treating the underlying cause is essential: For medically-caused odor, surface-level treatments are insufficient. Addressing the root cause, such as managing diet for TMAU or treating organ dysfunction, is necessary.

Introduction to Unusual Body Odor

Unpleasant body odor is a common concern, but when it is strong, persistent, and unaffected by standard hygiene, it can be a sign of an underlying health problem. Rather than originating from sweat alone, these odors are often a result of metabolic disorders, bacterial overgrowth, or organ dysfunction. Conditions can range from rare genetic diseases to more common issues like uncontrolled diabetes or certain infections.

Trimethylaminuria (TMAU): The Fish Odor Syndrome

Trimethylaminuria, often called “fish odor syndrome,” is a rare metabolic disorder where the body cannot properly break down the compound trimethylamine (TMA).

Causes of TMAU

Genetic Mutation: The primary cause is a mutation in the FMO3 gene, which produces the flavin-containing monooxygenase 3 enzyme. A deficiency in this enzyme prevents the liver from converting foul-smelling TMA into its odorless form.
Dietary Factors: TMA is produced by gut bacteria when digesting certain foods. For individuals with TMAU, foods high in choline and carnitine, such as eggs, liver, beans, certain legumes, and marine fish, can trigger or worsen symptoms.
Other Causes: In some cases, secondary TMAU can occur in adults with liver or kidney disease, or transiently in some healthy women during menstruation.

Symptoms and Social Impact

The most prominent symptom is a powerful, fishy odor released through sweat, urine, breath, and reproductive fluids. This can cause significant social anxiety, isolation, and depression for affected individuals, profoundly impacting their quality of life.

Bromhidrosis: Excessive Body Odor

Bromhidrosis is a chronic condition characterized by excessive, unpleasant body odor caused by bacterial breakdown of sweat. It is more common than metabolic disorders and is primarily linked to the apocrine sweat glands.

Types and Causes

Apocrine Bromhidrosis: The most common type, it occurs after puberty when apocrine glands become active. Bacteria on the skin decompose the oily, odorless secretions from these glands, producing a foul smell.
Eccrine Bromhidrosis: Less common, this type is caused by bacteria breaking down keratin softened by eccrine sweat. It can be triggered by ingesting certain foods, medications, or toxins.
Contributory Factors: Risk factors include obesity, diabetes mellitus, excessive sweating (hyperhidrosis), and certain skin infections like erythrasma.

Management and Treatment

Treatment options range from simple hygiene practices to more advanced medical interventions.

Antibacterial soaps and regular washing.
Antiperspirants to reduce sweat.
Botulinum toxin injections to temporarily block sweat glands.
Hair removal to reduce the surface area where bacteria can thrive.

Systemic Conditions and Their Odors

Beyond skin and genetic causes, several systemic diseases can produce distinctive and medically significant body odors.

Liver Disease (Fetor Hepaticus)

When the liver fails to filter toxins from the blood, these substances can be released through the breath and skin, creating a musty, pungent, or garlicky smell. This condition, known as fetor hepaticus, is a serious sign of advanced liver disease.

Kidney Failure (Uremic Fetor)

Kidney failure leads to the buildup of urea and other waste products in the blood. The body expels this excess urea through the breath, where it breaks down into ammonia, causing a urine-like or metallic odor. This is a symptom of advanced kidney disease.

Diabetic Ketoacidosis (DKA)

Diabetic ketoacidosis is a life-threatening complication of diabetes. When the body lacks insulin, it burns fat for energy, producing acidic ketones. The buildup of acetone, a type of ketone, results in a distinct fruity or nail polish remover-like odor on the breath.

Comparison of Body Odor Conditions


Condition	Cause	Characteristic Odor	Key Symptom	Medical Urgency
Trimethylaminuria (TMAU)	Genetic deficiency of FMO3 enzyme, preventing breakdown of trimethylamine.	Fishy, pungent smell	Body odor from sweat, breath, urine.	Non-emergency, but requires diagnosis and management.
Bromhidrosis	Bacterial breakdown of sweat from apocrine glands.	Sour, rancid smell	Excessive, offensive body odor from certain areas.	Primarily social/psychological concern, not life-threatening.
Fetor Hepaticus	Advanced liver failure, buildup of toxins.	Musty, garlicky, sometimes sweet	Persistent bad breath, skin odor.	High Medical Urgency: Sign of severe liver dysfunction.
Diabetic Ketoacidosis (DKA)	Uncontrolled diabetes, high ketone levels.	Fruity, acetone-like (nail polish remover)	Fruity breath, dry mouth, frequent urination, confusion.	Emergency Medical Situation: Can be life-threatening.
Uremic Fetor	Advanced kidney failure, urea buildup.	Urine-like, metallic taste/smell	Ammonia breath, metallic taste in mouth, fatigue.	High Medical Urgency: Sign of severe kidney failure.

Steps to Take if Concerned

If you or someone you know experiences a persistent, unusual body odor that does not improve with standard hygiene, it's essential to seek professional medical advice. While many of these conditions are rare, a proper diagnosis can lead to effective management and treatment.

Consult a Doctor: Your primary care physician can evaluate your symptoms, medical history, and determine if further investigation is needed. Mentioning the specific odor can be a valuable clue.
Specialist Referral: Depending on the initial findings, a doctor may refer you to a specialist, such as an endocrinologist for diabetes concerns, a gastroenterologist for liver issues, or a dermatologist for skin-related bromhidrosis.
Diagnostic Testing: Tests can include urine tests for TMAU, blood tests to check liver and kidney function, or a metabolic panel to assess for DKA.
Dietary and Lifestyle Changes: For some conditions like TMAU, managing the odor can involve avoiding certain foods. For bromhidrosis, improved hygiene and antiperspirants can help. A doctor can provide specific recommendations.
Mental Health Support: For conditions that cause social distress, psychological counseling can be a critical part of a comprehensive treatment plan to cope with emotional impacts.

Conclusion

While a strong body odor is most often tied to bacteria and poor hygiene, it can occasionally signal a serious underlying medical condition. From the fishy smell of Trimethylaminuria to the fruity breath of diabetic ketoacidosis, different conditions produce different odors that can point to their root cause. Recognizing these unique smells is the first step toward getting an accurate diagnosis and effective treatment, ultimately improving not only physical health but also quality of life.

For more detailed information on specific medical conditions, always consult authoritative medical sources, such as the National Institutes of Health.

Frequently Asked Questions

Yes, poor hygiene can cause a very bad smell, but typically this is resolved with regular washing. When the odor is extremely persistent despite good hygiene, it is more likely to be related to an underlying medical condition like bromhidrosis or a metabolic disorder.

No, Trimethylaminuria is not a medical emergency, but it can cause significant psychological distress and social isolation due to the persistent fishy odor. Proper diagnosis and management are important for a person's quality of life.

You should start by seeing your primary care physician. Based on your symptoms and a preliminary exam, they may refer you to a specialist such as a dermatologist for skin-related issues or an endocrinologist if a metabolic disorder is suspected.

Yes, diet plays a significant role in conditions like Trimethylaminuria. Avoiding foods high in choline and carnitine, such as eggs, beans, and certain types of fish, can help reduce the amount of odor-causing trimethylamine produced by gut bacteria.

The fruity breath of DKA can be subtle at first and is often accompanied by other serious symptoms like excessive thirst, frequent urination, and confusion. It is an indication of a medical emergency and should be treated seriously.

Yes, anxiety and stress can trigger excessive sweating, primarily from apocrine glands. This moisture can be broken down by bacteria, potentially leading to a more noticeable body odor. However, persistent, strong odor often indicates more than just stress.

Normal body odor is typically a result of bacteria on the skin and can be managed with standard hygiene. Medically-related odors are often constant, distinctive (like fish, fruit, or ammonia), and originate from within the body, indicating a metabolic or organ function issue.