Loss of Smell: Understanding the Causes and Your Path to Recovery

Your sense of smell does more than help you enjoy your morning coffee or notice when something is burning on the stove. It plays a vital role in taste, appetite, emotional memories, and even safety. When smell becomes diminished or disappears entirely, it can significantly affect quality of life. At Capital ENT, our specialists help patients understand what may be causing their smell loss and explore options for recovery.

What Is Smell Loss?

There are three words worth knowing. Anosmia is the complete loss of smell. Hyposmia is a reduced ability to smell. Parosmia is when smells are still there but come through wrong, often unpleasantly. Phantosmia is smelling something that is not there at all, commonly smoke or something burning.

How the loss started is one of the most useful clues we have. Smell that vanishes abruptly, often right after an illness, points toward viral injury to the smell nerves. Smell that fades gradually and comes and goes points toward sinus inflammation or polyps blocking odors from reaching the smell receptors. Those two paths lead to different treatments, which is why we ask so much about the timeline.

Common Causes of Smell Loss

Understanding what is behind your smell loss is the first step toward recovery. Several conditions can affect your ability to smell.

Upper Respiratory Infections

Viral infections are the most frequent cause of temporary smell loss. The common cold and influenza have always done this, and since 2020 COVID-19 has become a leading cause. The virus damages the olfactory nerve cells that detect odors, and because those cells can regenerate, smell usually returns over weeks to months.

Some people are left with something stranger than absence. In parosmia, smells come back distorted, and familiar things like coffee, onions, or a partner's shampoo turn foul. It is disorienting and it is real. In a Danish cohort of 190 patients followed after COVID-19 smell loss, parosmia was present in about three quarters of them, and no baseline feature predicted who would keep it (Mogensen et al., The Laryngoscope, 2026). Encouragingly, those with persistent parosmia did tend to show measurable improvement in smell testing over time.

Chronic Sinusitis and Nasal Polyps

Ongoing inflammation in the sinuses can block odor molecules from reaching the olfactory receptors high in the nasal cavity. Smell loss is one of the more overlooked signs of chronic sinusitis, and it often arrives so gradually that patients do not connect the two. Nasal polyps, which are soft, noncancerous growths in the nasal passages, often contribute to this obstruction. When inflammation or polyps are the cause, treatment may help restore smell. Our physicians offer several approaches, including polypectomy for polyp removal and endoscopic sinus surgery for more complex cases.

Allergies

Allergies cause swelling and congestion that can temporarily dull your ability to smell, and in Austin that often follows the cedar and oak seasons. Managing allergies through avoidance strategies or treatments such as allergy immunotherapy may help improve smell function over time.

Head Trauma

A blow to the head can shear the delicate nerve fibers running from the nose up into the brain, and it does not always take a severe injury to do it. Recovery varies widely. Some people regain smell over months; for others the change is permanent.

Age-Related Changes

Smell fades with age, usually starting after 60, and it happens slowly enough that most people do not notice until someone points it out. That decline cannot be reversed. It is still worth an evaluation, because the treatable causes look the same from the inside.

Other Potential Causes

Less common causes include certain medications, exposure to toxic chemicals, and, rarely, growths in the nasal cavity or at the base of the brain. Smell loss can also be an early sign of neurologic conditions such as Parkinson's disease, sometimes appearing years before other symptoms. That is one reason a gradual, unexplained decline in smell deserves an evaluation rather than being written off as aging. A thorough evaluation can help identify or rule out these possibilities.

What Does Recovery Look Like?

Recovery from smell loss depends heavily on the underlying cause. When inflammation or obstruction is responsible, treating these issues often leads to meaningful improvement. For post-viral smell loss, the outlook is better than most people fear. A meta-analysis in The BMJ pooling 3,699 COVID-19 patients found that smell had returned in about 74 percent by 30 days, 86 percent by 60 days, 90 percent by 90 days, and roughly 96 percent by 180 days (Tan et al., 2022). An estimated 5.6 percent were left with lasting smell dysfunction.

Two caveats from the same analysis. Recovery was less likely in women, in those whose loss was severe at the outset, and in those with nasal congestion. And these are population numbers, not a schedule; individual recovery does not follow a clock, and late improvement well past six months is well documented.

Olfactory training is the most widely used self-directed approach. It means sniffing the same set of strong scents twice a day for several months, classically rose, lemon, clove, and eucalyptus, to give the recovering system repeated practice. An international position paper on olfactory dysfunction supports it across a range of causes (Hummel et al., Rhinology Supplement, 2017).

It is recommended for persistent post-viral loss, it costs almost nothing, and it carries no risk, which is why we suggest it routinely.

The evidence behind it is mixed. A placebo-controlled randomized trial in post-COVID smell loss found 12 weeks of classic training did not significantly outperform odor-free placebo training, and that parosmia blunted whatever effect there was (Mogensen et al., The Laryngoscope, 2025). Other work across a range of causes is more favorable, and roughly half of COVID-19 patients do improve with training. Taken together: it helps some people and not others, there is no reliable way yet to predict who, and the only cost of trying is your time. If months of training have produced nothing, that is a known pattern rather than a personal failure, and it is a good reason to be evaluated instead of continuing alone.

It is important to have realistic expectations. While many patients experience at least partial recovery, some causes of smell loss, particularly those involving nerve damage, may result in permanent changes. Our team can help you understand what to expect based on your specific situation.

The Safety Part People Overlook

Smell is not only about pleasure. It is how you detect a gas leak, a fire, or food that has turned. Losing it removes a warning system, and that risk is easy to forget once the initial shock of the loss wears off.

A few practical steps while your smell is impaired:

• Check that smoke alarms work and consider adding a natural gas or carbon monoxide detector
• Go by expiration dates rather than sniffing food, and be cautious with leftovers
• Take extra care with the stove, and consider a timer as a backup habit
• Ask someone you trust to be a second nose for anything questionable

Appetite is worth watching too. Much of what we call taste is actually smell, so people who lose it often stop enjoying food and eat less without noticing. Unintended weight loss and low mood are both common with smell loss, and both are worth raising at your visit.

When Should You See a Specialist?

Consider scheduling an evaluation with an ENT specialist if you experience sudden or unexplained loss of smell, smell loss lasting more than two weeks after a cold or respiratory infection, gradual decline in smell that affects your daily life, distorted smell perception (parosmia), or smell loss accompanied by other symptoms such as nasal obstruction, facial pain, or headaches. Early evaluation can help identify treatable causes and improve your chances of recovery.

How Our Team Can Help

We start with your history, because the timeline usually points at the cause. Did it vanish overnight after an illness, or fade over years? Is your nose blocked? Was there a head injury? Then we examine the nasal passages, often with a thin endoscope to see the areas a standard exam cannot reach, and order imaging when the picture calls for it.

If you have been living with smell loss and wondering whether anything can be done, we encourage you to reach out. Understanding the cause is the first step toward finding solutions.

Sources

• Hummel T, Whitcroft KL, Andrews P, et al. Position paper on olfactory dysfunction. Rhinology Supplement. 2017;54(26):1-30.
• Tan BKJ, Han R, Zhao JJ, et al. Prognosis and persistence of smell and taste dysfunction in patients with covid-19: meta-analysis with parametric cure modelling of recovery curves. The BMJ. 2022;378:e069503. doi:10.1136/bmj-2021-069503
• Mogensen DG, Aanaes K, Andersen IB, et al. Effect of Olfactory Training in COVID-19 Related Olfactory Dysfunction: A Placebo-Controlled Trial. The Laryngoscope. 2025;135(12):4849-4857. doi:10.1002/lary.32275
• Mogensen DG, Jacobsen RK, Backer V, et al. Quantitative Olfactory Dysfunction and Parosmia After COVID-19: An Observational Cohort Study. The Laryngoscope. 2026;136(2):918-926. doi:10.1002/lary.70235
• American Academy of Otolaryngology-Head and Neck Surgery. Smell Disorders. ENThealth.org.