Parosmia: What It Is, Treatment & How Long it Lasts

Updated in March 2022

Parosmia is a condition that is characterized by a distortion in your sense of smell. Some people may have difficulty identifying specific smells, or notice no changes with odor intensity. Others may experience changes to smells that were once pleasant or normal, and find them intolerable. Because smell is directly related to taste, some people may also find previously enjoyable meals repulsive.  

This abnormality occurs due to damage to olfactory nerves that send signals to the brain. These nerves help to identify smells, and can be negatively affected by bacterial or viral respiratory infections, like sinusitis, the common cold or COVID-19. 

Parosmia is diagnosed by an otolaryngologist (an ears, nose and throat specialist, or ENT) through exams that look for the cause. Treatment is initiated as indicated, and can be completed with medication or with smell training. 

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Main symptoms

The main symptom of parosmia is a temporary disturbance to smelling abilities. You may notice difficulty identifying or even noticing certain smells. Some people may find certain smells they once found pleasant or normal to be intolerable or repulsing. This can be the case with food odors or perfumes. 

As a result, you may have difficulty eating or experience nausea when eating, as the ability to smell or taste are directly related, leading to a lack of appetite and weight loss. 

Parosmia can negatively affect your quality of life, leading to mood changes, anxiety or depression.

How it is diagnosed 

Parosmia is diagnosed by an ENT following a thorough assessment. He or she may ask questions about any recent infections, lifestyle habits (like cigarette use), current health status, and family history of cancer or neurological conditions. 

Although there is no specific test available to check for parosmia, the doctor may opt to present you with many varying smells to see whether you can identify and describe the smell. 

Other exams the doctor may order are a CT scan, MRI or even a nasal biopsy to rule out the presence of cancer or a neurological condition. 

Possible causes 

Parosmia is caused by damage to olfactory nerves, which are responsible for sending signals to the brain to identify smells. Damage to these nerves can change the way these signals reach the brain. 

Some conditions that can cause olfactory nerve damage and lead to parosmia include: 

  • The common cold
  • Sinusitis
  • COVID-19
  • Exposure to or use of cigarettes 
  • Parkinson's disease 
  • Alzheimer’s
  • Brain trauma
  • Huntington's disease 
  • Brain tumors or olfactory nerve tumors
  • Chemotherapy or radiation therapy 

It is important to see your doctor or an ENT if you notice any changes to your ability to smell, so that a diagnosis can be confirmed and adequate treatment can be initiated. 

Can COVID-19 cause parosmia

Some studies show that some people can develop parsomia when recovering from loss of smell caused by COVID-19. This occurs due to nerve damage from the coronavirus. 

Although it is rare, parosmia can emerge about 1 to 2 months after the initial infection of the coronavirus, and it can persist for 8 or more months. Many people experience constant foul odors, like rotten meat, which can affect your quality of life. 

How it is treated

Treatment for parosmia varies according to the cause. In cases where parosmia is caused by factors like smoking, medication or cancer treatment, the reduction or elimination of these substances can often restore smelling capabilities.

Nonetheless, if parasmia is constant, the doctor can prescribe medication like clonazepam, phenytoin, topiramate or valproic acid to help relieve symptoms. 

When parosmia is caused by COVID-19, it will generally improve on its own over time without any interventions. However, you can participate in smell training once you have recovered from the virus. 

Smell training involves the use of 3 or 4 different smells, like essential oils (lemon, rose, cloves and eucalyptus for example) and inhaling these smells deeply for 20 seconds each time. You can do this twice a day for about 3 months or more. Although it can help with recovering your sense of smell, more scientific studies are needed to prove the efficacy of this therapy.