What is Parasomia: Causes, Symptoms, Treatment, Diagnosis, Surgery

What is Parosmia?

Parosmia is a kind of smell disorder where the part of the brain which recognizes the sense of smell, fails to do so and is unable to perceive different odors. While there can be various causes of parosmia, the main feature is the inability to differentiate between good and bad odors. This results in symptoms of parosmia. When suffering from parosmia, the brain’s olfactory lobe perceives the odor of any material to be offensive though actually it isn’t so. This makes the person consider pleasant and nice odors of any material to be foul and offensive. As a symptom of parosmia, it is common for people to recognize pleasant odors to be that of burning, rotten, vomit, chemicals or fecal odor.

Not being able to distinguish between the smell of various food items, make people having parosmia distressed in their daily lives. It is important to analyze the causes, symptoms and treatment of parosmia.

What is Parosmia?

Causes of Parosmia

To understand what causes parosmia, it is essential to understand the way the olfactory system functions. The Olfactory Sensory Neurons (OSN) are the specialized cells found in the mucus membrane lining of the nose. Being receptor cells, these cells receive all the smell around and pass this sensation to the olfactory lobe in the brain. The Olfactory Sensory Neurons (OSN) then evaluates the smell perceived by it.

If Olfactory Sensory Neurons (OSN) is damaged, as in the case of parosmia, it sends a signal to the brain of distorted smell even if in reality it isn’t so. This eventually results in parosmia and presents with symptoms of parosmia.

Here are the major causes of parosmia in most cases.

  • Parosmia Caused Due to Upper Respiratory Tract Infection – This is one of the most common causes of parosmia. The chances of having parosmia increases in conditions like sinusitis, chronic rhinitis, bronchitis or sore throat. As the sense of smell gets distorted in these diseases because of damage to the Olfactory Sensory Neurons (OSN), they become a cause of parosmia too.
  • Parosmia Caused Due to Nasal Polyps – Nasal polyps are benign growths which occur in the sinuses and nasal cavity. Nasal polyps can affect proper functioning of the Olfactory Sensory Neurons (OSN), which can cause parosmia. In nasal polyps, the inner part of the nose gets inflamed and the growth of the polyp makes the nose feel stuffy. This can also affect the OSN, altering the normal perception of smell and causes parosmia.
  • Parosmia Caused Due to Smoking – Smoking is another important cause of parosmia. Statistics reveal that almost 30 percent of patients suffering from parosmia are chronic smokers. Studies have shown that chronic smoking increases the risk of parosmia, not only due to increases respiratory illnesses but also by causing damage to the sensory cells in the nose. As these cells are responsible for transmitting different odors to the human brain, the function of odor differentiation is affected causing parosmia.
  • Head Injury Can Cause Parosmia – The olfactory bulb helps to differentiate between several smells. When the olfactory bulb in the brain gets injured or damaged due to any kind of injury to the brain, it can cause parosmia.
  • Neurological Diseases and Parosmia – Alzheimer disease, Parkinson’s disease and seizures are some common neurological diseases, which can damage specific areas of the brain permanently. If the areas involved in smell sensation get damaged, they too can cause parosmia.
  • Parosmia Caused Due to Aging – As a person ages, the body’s ability to taste and smell decreases, which can eventually cause parosmia. A recent study revealed that around 25 percent of Americans over 50 years of age complained of diminished sense of smell. Age-related parosmia prevents a person from identifying the natural odor of a substance making it a common cause of parosmia.
  • Harmful Chemicals and Parosmia – The smoke emitted from harmful acids and chemicals can damage the sensory cells in nose. It can result in distorted smell with regular exposure and cause parosmia in the long run. People exposed to hazardous chemicals or acids as a part of their occupation are at an increased risk of causing parosmia.
  • Certain Medications – Certain medications, especially antibiotics when used for a long time can impair a person’s ability to smell and can commonly cause parosmia.

Symptoms of Parosmia

A person experiencing parosmia, is not able to identify the correct smell of any substance. The main symptom of parosmia is this inability to differentiate between pleasant and unpleasant odors. As every pleasant fragrance is also perceived as an unpleasant odor, the person is not able to enjoy different life experiences. The person with parosmia often finds it difficult to eat and enjoy various food items as the brain is unable to differentiate one food flavor and aroma from another.

Another common symptom of parosmia is the persistent foul smell that almost all patients complain about. Such a persistent smell makes the person feel sick and any smell is sensed as rotten flesh or fecal odor. For example, a person with parosmia can perceive the sweet smell of mangoes to be burning and chemical.

Treatment of Parosmia

While there is no specific treatment of parosmia, this condition is believed to get better with time. Treatment of parosmia also mainly includes treating the causes of parosmia. Medicines to relieve respiratory disorders, stuffy nose, treatment or surgery for nasal polyps and quitting smoking is recommended.

Over a period of time, the symptoms slowly start to lessen and this is the best treatment of parosmia. The time required to show improvement in symptoms and treatment of parosmia to show effect may vary. In some people it may also take several years for improvement in parosmia.

In medical management, a drug named levo-dopamine, is used by physicians to control parosmia. In some cases, if parosmia does not improve for a long time, doesn’t respond to treatment or becomes extremely annoying, surgical treatment of parosmia may be considered, Surgery for parosmia includes a procedure in which the olfactory bulb is completely destroyed.


Parosmia, can be a troublesome and irritating condition, where one, not only suffers from a distorted smell but also finds it difficult to enjoy food. People suffering from parosmia need to understand the condition and seek appropriate medical advice. It is important to treat the underlying causes of parosmia and remain patient as the symptoms of parosmia can gradually decrease over time.

Team PainAssist
Team PainAssist
Written, Edited or Reviewed By: Team PainAssist, Pain Assist Inc. This article does not provide medical advice. See disclaimer
Last Modified On:May 4, 2022

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