Parosmia is a condition that causes a distortion in the sense of smell, making familiar odors seem unpleasant or different. This change can also affect taste, causing foods that were once enjoyable to become unappealing.
Parosmia usually occurs due to damage to the olfactory nerves, which help send smell signals to the brain. This damage is often linked to infections like COVID-19, sinusitis, or the common cold, as well as other neurological conditions.
Parosmia is diagnosed by an ENT specialist through clinical evaluation and tests to identify the underlying cause. Treatment depends on the cause and may include medication or smell training to help restore normal smell perception.
Main symptoms
The main symptom of parosmia is a temporary change in your sense of smell. You may have trouble noticing certain odors or telling them apart, and smells you once found pleasant or neutral can become intolerable or unpleasant, especially food odors or perfumes.
Because smell and taste are closely linked, you may find it hard to eat or feel nauseated when eating, which can lead to reduced appetite and weight loss. According to the National Institute on Deafness and Other Communication Disorders, smell problems can affect eating habits, contribute to weight changes, and, in severe cases, may lead to depression.
Confirming a diagnosis
Parosmia is diagnosed by an ENT specialist after a thorough assessment. The doctor may ask about recent infections, lifestyle habits (such as smoking), your current health, and any family history of cancer or neurological conditions.
Although there is no specific test for parosmia, the doctor may expose you to different smells to see whether you can recognize and describe them. The doctor may also order tests such as a CT scan, MRI, or nasal biopsy to rule out cancer or neurological diseases.
Possible causes
Parosmia happens when the olfactory nerves, which carry smell signals to the brain, are damaged. This damage can change how these signals reach the brain and how smells are perceived.
Some conditions that can damage the olfactory nerves and lead to parosmia include:
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The common cold
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Exposure to or use of cigarettes
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Parkinson's disease
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Alzheimer’s disease
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Traumatic brain injury (TBI)
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Brain tumors or tumors affecting the olfactory nerves
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Chemotherapy or radiation therapy
It is important to see your primary care provider or an ENT specialist if you notice any changes in your sense of smell, so the cause can be identified and appropriate treatment started.
Can COVID-19 cause parosmia?
Some studies suggest that certain people develop parosmia while recovering from COVID‑19-related loss of smell. This seems to happen because the coronavirus can damage the nerves involved in smell.
Although it is uncommon, parosmia may appear about 1 to 2 months after the initial infection and can last for 8 months or longer. Many people report persistent unpleasant smells, such as rotten meat, which can significantly affect quality of life.
Treatment options
Treatment for parosmia depends on the underlying cause. When it is related to smoking, medications, or cancer treatments, reducing or stopping these triggers can often help restore the sense of smell.
If parosmia is persistent, a doctor may prescribe medications such as clonazepam, phenytoin, topiramate, or valproic acid to help relieve symptoms.
When parosmia is caused by COVID-19, it usually improves on its own over time, without specific treatment. However, once you have recovered from the infection, you can try smell training to support recovery.
Smell training typically uses 3 or 4 different scents, such as essential oils like lemon, rose, clove, and eucalyptus. You inhale each scent deeply for about 20 seconds, twice a day, for around 3 months or longer. This approach may help improve your sense of smell, but more research is needed to confirm how effective it is.