Most people rarely think about their sense of smell until it begins to change.
For some individuals, the change is sudden and obvious. Others notice a more frustrating pattern: their sense of smell seems to come and go without explanation.
One week they can smell coffee brewing in the morning and enjoy the flavors of their favorite meals. A few weeks later, those same smells seem muted or absent.
Then, just as unexpectedly, their sense of smell returns.
If this sounds familiar, you’re not alone.
Fluctuating smell loss is a surprisingly common complaint among patients with nasal and sinus disorders. While temporary smell changes can occur during colds or allergies, recurring or persistent smell loss often points to an underlying issue that deserves further evaluation.
Understanding how smell works—and what can interfere with it—can help identify the cause and guide effective treatment.
Why Your Sense of Smell Is More Important Than You Think
Many people underestimate the importance of smell until they begin to lose it.
Your sense of smell contributes to:
- Enjoyment of food
- Detection of smoke and fire
- Awareness of gas leaks
- Recognition of environmental hazards
- Memory and emotional experiences
In fact, much of what we perceive as taste actually comes from smell.
Patients with smell loss frequently report that foods become bland, less enjoyable, or difficult to distinguish from one another.
For some, smell loss can significantly affect quality of life.
How Smell Actually Works
The process of smelling is surprisingly complex.
Inside the upper portion of the nasal cavity is a specialized area called the olfactory cleft. This region contains smell receptors that detect odor molecules as air passes through the nose.
For normal smell function to occur:
- Air must move freely through the nose.
- Odor molecules must reach the smell receptors.
- The receptors must function properly.
- Signals must be transmitted to the brain.
Problems at any step in this process can lead to smell impairment.
Why Smell Often Comes and Goes
One of the clues that smell loss may be related to sinus disease is fluctuation.
Unlike many neurologic causes of smell loss, sinus-related smell problems often improve and worsen depending on the amount of inflammation present.
Patients commonly report:
- Better smell after steroid treatment
- Worse smell during allergy season
- Temporary improvement after sinus rinses
- Smell loss during sinus infections
- Fluctuations from week to week
These changing symptoms often suggest that inflammation is affecting airflow to the smell receptors.
Chronic Sinus Inflammation
One of the most common causes of fluctuating smell loss is chronic sinus inflammation.
When inflammation develops inside the nose and sinuses, swelling can block the pathway that allows odor molecules to reach the smell receptors.
Patients may experience:
- Congestion
- Facial pressure
- Postnasal drip
- Reduced smell
- Altered taste
Sometimes smell loss becomes the most bothersome symptom, even when other sinus symptoms are relatively mild.
Nasal Polyps and Smell Loss
Among sinus conditions, nasal polyps are one of the strongest predictors of smell impairment.
Nasal polyps are benign inflammatory growths that develop within the nasal cavity and sinuses.
As polyps enlarge, they can:
- Block airflow
- Obstruct the olfactory cleft
- Prevent odor molecules from reaching smell receptors
Many patients with polyps report:
- Complete loss of smell
- Smell that fluctuates dramatically
- Temporary improvement with oral steroids
- Progressive worsening over time
In some cases, changes in smell become an important marker of disease activity.
Allergies Can Affect Smell Too
Patients often associate smell loss with sinus infections, but allergies can also play a major role.
Allergic inflammation causes swelling within the nasal passages, making it harder for air to reach the smell receptors.
Common triggers include:
- Tree pollen
- Grass pollen
- Weed pollen
- Dust mites
- Pet dander
- Mold
Many individuals notice their smell worsens during allergy season and improves when allergen exposure decreases.
Sinus Infections and Temporary Smell Loss
Acute sinus infections frequently affect smell.
During an infection:
- Swelling increases
- Mucus production rises
- Airflow decreases
These changes temporarily interfere with smell function.
Fortunately, many patients recover their sense of smell once the infection resolves.
However, repeated infections may indicate chronic sinus inflammation that deserves further investigation.
Why Taste Often Changes Too
Many patients say they have lost their sense of taste when the real problem is smell.
While the tongue detects basic tastes such as:
- Sweet
- Salty
- Sour
- Bitter
Most flavor perception comes from smell.
This explains why food often tastes bland when smell is impaired.
Patients frequently report:
- Difficulty appreciating flavors
- Reduced enjoyment of meals
- Loss of interest in food
Improving smell often improves taste perception as well.
Could COVID Still Be Contributing?
Since the COVID-19 pandemic, many patients have become more aware of smell dysfunction.
While COVID can cause smell loss through mechanisms that differ from traditional sinus disease, some patients continue to experience:
- Persistent smell loss
- Distorted smells
- Fluctuating smell function
A thorough evaluation can help determine whether symptoms are related to chronic sinus inflammation, prior viral injury, or both.
When Should You See a Specialist?
Occasional smell changes during a cold are common.
However, evaluation may be worthwhile if:
- Smell repeatedly comes and goes
- Symptoms persist for months
- Smell loss is accompanied by congestion
- You have recurrent sinus infections
- Your quality of life is affected
Because smell loss often reflects underlying inflammation, identifying the cause early may improve treatment options.
How Smell Loss Is Evaluated
A comprehensive sinus evaluation often includes several components.
Nasal Endoscopy
A small camera is used to examine:
- Nasal passages
- Sinus drainage pathways
- Areas of inflammation
- Presence of nasal polyps
Sinus CT Imaging
CT scans help identify:
- Chronic sinus inflammation
- Polyps
- Blocked drainage pathways
- Structural abnormalities
Allergy Assessment
Allergy testing may be recommended when allergies are suspected to be contributing to symptoms.
Treatment Options
Treatment depends on the underlying cause.
Medical Therapy
Common treatments may include:
- Nasal steroid sprays
- Saline irrigations
- Allergy medications
- Oral medications when appropriate
Allergy Management
Reducing allergic inflammation often improves smell function.
Nasal Polyp Treatment
Treatment may involve:
- Medications
- Biologic therapies
- Office procedures
- Sinus surgery in selected patients
Management of Chronic Sinus Disease
Improving sinus drainage and controlling inflammation frequently helps restore smell.
The Bottom Line
A fluctuating sense of smell is often a sign that something is affecting the normal function of the nose and sinuses.
While temporary smell changes can occur with infections or allergies, repeated or persistent smell loss deserves further evaluation.
In many cases, identifying and treating the underlying cause can improve smell, enhance enjoyment of food, and significantly improve quality of life.
Frequently Asked Questions
Why does my sense of smell come and go?
Fluctuating smell is often caused by changing levels of inflammation within the nose and sinuses.
Can allergies cause smell loss?
Yes. Allergic swelling can interfere with airflow reaching the smell receptors.
Do nasal polyps affect smell?
Absolutely. Nasal polyps are one of the most common causes of significant smell impairment.
Can chronic sinusitis cause loss of smell?
Yes. Chronic inflammation frequently affects smell function and may cause symptoms to fluctuate.
Will treatment improve my sense of smell?
Many patients experience improvement when the underlying cause is identified and appropriately treated.
