What diseases can we have if we had a poor smelling skill?

September 21, 2025 •

5 min read

According to the National Institutes of Health, millions of adults experience a reduced sense of smell, known as hyposmia, or a total loss, called anosmia. These conditions are not just a nuisance; if you have a poor smelling skill, it can be a sign of various underlying medical issues, ranging from minor infections to serious neurological disorders.

Quick Summary

A poor or lost sense of smell can be caused by common issues like colds and infections, but also signals more serious diseases such as neurodegenerative disorders, sinus conditions, and other systemic illnesses. It's crucial to identify the root cause for proper diagnosis and treatment.

Key Points

Poor Smell isn't Always Minor: Diminished or lost sense of smell (hyposmia or anosmia) can be a sign of a more serious underlying health issue, not just a nuisance.
Neurological Connections Exist: Progressive loss of smell can be an early indicator of neurodegenerative diseases such as Parkinson's and Alzheimer's, often appearing years before other symptoms.
Infections are Common Causes: A frequent culprit is an upper respiratory infection, like the common cold, flu, or COVID-19, which can temporarily damage the olfactory system.
Structural Issues Play a Role: Physical obstructions within the nose, including chronic sinusitis, nasal polyps, or a deviated septum, can block scent detection.
Medications and Toxins are Factors: Certain medications and exposure to toxic chemicals or smoking can also affect olfactory function.
Safety Precautions are Essential: Losing your sense of smell impairs your ability to detect dangers like spoiled food, gas leaks, and smoke, so safety devices like detectors are crucial.
Medical Consultation is Important: If a poor sense of smell is persistent or unexplained, a medical evaluation by an ENT or other specialist is necessary to diagnose the cause.

Understanding Olfactory Dysfunction

Problems with the sense of smell are collectively known as olfactory dysfunction. Hyposmia refers to a reduced ability to detect odors, while anosmia is the complete inability to smell anything. Other related conditions include parosmia (distorted perception of smells) and phantosmia (smelling odors that aren't there). While a temporary loss is common after a cold or flu, persistent or unexplained changes warrant medical attention as they can indicate more significant health problems.

Short-Term Causes: Infections and Inflammation

Many cases of a poor sense of smell are temporary and resolve once the underlying infection clears. The most frequent culprits are inflammatory conditions that affect the nasal passages.

Viral Infections

Upper Respiratory Infections: Common colds, the flu, and viruses like COVID-19 are primary causes. These viruses can temporarily damage the olfactory sensory neurons, which are responsible for detecting smells. Recovery can take weeks or months, and some individuals may experience parosmia during the healing process.
Sinusitis: Both acute and chronic sinus infections cause inflammation and congestion that can block odor molecules from reaching the olfactory nerve at the top of the nasal cavity. Antibiotics or other treatments for the infection often restore the sense of smell.

Nasal Obstructions

Allergies: Conditions like hay fever trigger inflammation in the nasal passages, leading to congestion and a reduced sense of smell.
Nasal Polyps: These are benign, teardrop-shaped growths that can form inside the nose or sinuses. They can block the nasal passages and lead to significant smell reduction.

Long-Term and Serious Conditions

When a poor sense of smell persists beyond the resolution of an infection or has no obvious cause, it can be a sign of a more serious, chronic condition.

Neurodegenerative Disorders

Loss of smell is an early, well-documented symptom for several neurodegenerative diseases, often appearing years before motor or cognitive symptoms.

Parkinson's Disease: An estimated 90% of people with Parkinson's experience a diminished sense of smell, often years before the disease is diagnosed. This loss is linked to damage in the brain's olfactory pathways.
Alzheimer's Disease: Similar to Parkinson's, olfactory dysfunction is an early sign of Alzheimer's. The brain regions responsible for smell are among the first to be affected by the disease.
Multiple Sclerosis (MS): While less common, some MS patients experience a loss of smell due to damage to the central nervous system that affects the olfactory system.

Other Systemic Diseases

Diabetes: Poorly controlled diabetes can cause nerve damage throughout the body, including the nerves associated with smell.
Hypertension: High blood pressure has been linked to a diminished sense of smell, though the exact relationship is still being studied.
Brain Tumors: Although rare, a tumor at the base of the skull or near the olfactory nerve can cause a progressive loss of smell.
Kallmann Syndrome: This is a rare genetic disorder characterized by a congenital loss of smell (being born without it) combined with delayed or absent puberty.

Medications and Environmental Factors

Certain medications and environmental exposures can also cause a decline in your sense of smell.

Medications

Antibiotics and Antihistamines: Some medications, including certain antibiotics and blood pressure medications, can cause olfactory changes as a side effect.
Intranasal Zinc: Overuse of intranasal zinc products for colds has been shown to cause permanent damage to the sense of smell.

Environmental Exposures

Chemicals: Long-term exposure to toxic chemicals, such as certain insecticides and solvents, can damage the olfactory system.
Smoking: Chronic smoking is known to dull the sense of smell and accelerate its decline over time.

Comparing Potential Causes of Poor Smell


Cause	Onset	Duration	Other Symptoms	Potential Seriousness
Viral Infection	Sudden	Temporary (days to months)	Congestion, fever, cough	Typically low; can be part of COVID-19 or flu
Chronic Sinusitis	Gradual	Persistent	Facial pressure, nasal drainage, pain	Moderate; can lead to other complications if untreated
Allergies	Seasonal/Triggered	Intermittent	Sneezing, runny nose, watery eyes	Low to Moderate; manageable with treatment
Nasal Polyps	Gradual	Persistent	Nasal obstruction, decreased taste	Moderate; requires medical evaluation, possibly surgery
Neurodegenerative Diseases	Gradual	Progressive/Permanent	Memory loss, tremors, cognitive decline	High; symptom of serious, progressive neurological disease
Head Trauma	Sudden	Temporary or Permanent	Headache, concussion symptoms	High; can signal serious brain injury
Medication	Coincides with start of medication	Reversible	Other side effects of the drug	Varies; requires medical consultation to change medications

What to Do If You Have a Poor Sense of Smell

If your poor sense of smell is new, unexplained, or doesn't improve after an infection has passed, you should consult a doctor, preferably an otolaryngologist (ENT). A proper diagnosis is the first step toward potential treatment, which can range from managing inflammation with medication to treating an underlying systemic disease.

Diagnosis and Treatment

Medical Evaluation: A healthcare provider will perform a physical exam, take a full medical history, and may conduct a “scratch and sniff” test to assess your sense of smell.
Imaging Tests: A CT scan or MRI may be ordered to look for nasal obstructions, tumors, or signs of neurological damage.
Underlying Condition Treatment: If a specific cause like sinusitis or a medication is identified, treating it will likely resolve the olfactory issue. For chronic conditions like neurodegenerative diseases, managing the disease is the priority.

Other Strategies

Olfactory Training: Also known as "smell training," this involves regularly sniffing a set of strong scents (like rose, lemon, eucalyptus, and cloves) to help retrain the olfactory system.
Address Safety Risks: Since a poor sense of smell can mask dangers like gas leaks or smoke, it is vital to install working smoke and carbon monoxide detectors and be vigilant about food spoilage.

Conclusion

A diminished or lost sense of smell should never be dismissed as merely an annoyance. While often a temporary side effect of a common cold, its persistence can be a crucial warning sign for conditions ranging from treatable nasal issues to serious neurological disorders. By seeking timely medical advice and understanding the potential causes, individuals can ensure any serious underlying health problems are properly identified and managed, protecting their overall health and quality of life.

For more detailed information on olfactory disorders, you can visit the National Institute on Deafness and Other Communication Disorders.

Frequently Asked Questions

Yes, in rare cases, a brain tumor located near the olfactory nerve can cause a progressive loss of smell. This is why persistent and unexplained olfactory issues require a thorough medical evaluation, including potential imaging tests.

Colds, flu, and other respiratory infections can cause inflammation and congestion in the nasal passages. This swelling physically blocks odor molecules from reaching the specialized nerves that detect smell. Viruses like COVID-19 can also directly damage these nerves.

Yes, it is common for the sense of smell to gradually decline with age, a condition known as presbyosmia. This is due to a natural loss of olfactory cells over time. However, any rapid or significant change should still be checked by a doctor.

Anosmia is the complete inability to detect any odors, while hyposmia is a reduced or diminished ability to smell. Both are types of olfactory dysfunction, but anosmia is the more severe form.

Olfactory training, which involves regularly sniffing a variety of specific scents, can be a helpful technique for retraining the brain to recognize smells, particularly after a viral infection. Consistency is key for potential recovery.

For safety, it's crucial to have working smoke and carbon monoxide detectors in your home. You should also be vigilant about checking expiration dates on food, as you may not be able to detect spoilage by smell.

You should see a doctor if your diminished or lost sense of smell doesn't improve after a cold or infection clears, or if it has no clear cause. It is especially important to seek medical advice if the condition is accompanied by other unexplained symptoms.