Ear, Nose and Throat Neurology / Neuroscience

What to know about phantom smells (phantosmia)

Phantosmia is the medical word used by doctors when a person smells something that is not actually there.

Phantosmia is also called a phantom smell or an olfactory hallucination. The smells vary from person to person but are usually unpleasant, such as burnt toast, metallic, or chemical smells.

Problems with the nose, such as sinusitis, or conditions of the nervous system or brain, including migraine, stroke, or schizophrenia can cause phantosmia.

In this article, we look at the causes and symptoms of phantosmia, when to see a doctor, and how to differentiate phantosmia from related conditions, such as parosmia.

What is phantosmia?

Phantosmia
A person with phantosmia may smell something that is not there.

Phantosmia is a disorder linked to a person’s sense of smell. It happens when a person can smell something that is not there.

The smell may only appear on one side of the nose, or it may affect both nostrils.

Phantosmia is relatively uncommon. It makes up around 10 to 20 percent of disorders related to the sense of smell. In most cases, phantosmia is not a cause for concern and will go away on its own.

However, phantosmia can be a sign of a serious underlying condition, so people should always discuss this symptom with their doctor.

Some phantom smells are pleasant, but people with phantosmia more often describe unpleasant, foul, or disgusting odors. These may include:

  • burnt toast
  • burning rubber
  • cigarette smoke
  • a chemical or metallic smell
  • a spoiled or rotting smell
  • a stale or moldy smell

People are often unable to identify the specific smell, or it may be a smell that they have never encountered before.

Phantosmia can feel distressing and may get in the way of daily life. It can influence a person’s sense of taste, leading to a reduced appetite and weight loss.


Causes of phantosmia

People may experience phantom smells for many reasons. They may be related to the nose, when the condition is known as peripheral phantosmia, or to the brain, which is called central phantosmia.

Problems with the nose or nasal cavity are the most common causes of smell-related disorders such as phantosmia. These include:

Otherwise, phantom smells can arise because of problems with how the brain understands smells. These include:

When phantosmia is related to nose problems, people may notice a stronger smell in one nostril than the other. Saline rinses and anesthetic pads can often help reduce the smell.

When phantosmia is related to the brain or central nervous system, the smells are often more persistent. They can be noticeable during the day and night, and both nostrils rather than only one experience the same smell.


Is it really a phantom smell?

Phantosmia may be amplified by a change in deodrant
A person may think they are noticing a phantom smell if they have changed hygiene products.

In some cases, people may believe they are noticing a phantom smell, when they may instead be noticing a real but unexpected smell.

Possible sources of unexpected smells include:

  • recent changes in deodorant or other hygiene products
  • new materials, products, or packaging
  • a new air-conditioning unit, heater, or air filter, which may still contain chemicals from the factory


Phantosmia vs. parosmia

Phantosmia is often confused with parosmia, which is a distorted sense of smell.

People with parosmia are smelling real-life smells, but they are distorted. For instance, the smell of flowers could trigger a smell of chemicals instead. Many people with parosmia also describe the distorted smells as unpleasant.

According to a 2013 review, phantosmia and parosmia often happen at the same time, and parosmia is more common than phantosmia.

Parosmia can be disturbing, and symptoms can range from mild to severe. Severe parosmia may be debilitating. People with severe parosmia may struggle to deal with their symptoms, even temporarily.

Diagnosis

To diagnose phantosmia, a doctor will first perform a physical exam of the person’s head and neck. They may ask about any other symptoms and perform tests to check the individual’s other senses.

A doctor may order an endoscopy or rhinoscopy to look into the nasal cavity and check for issues that could cause phantosmia. They may also request specific and comprehensive tests or refer people to a specialist.

Imaging tests, including CT scans, MRI scans, and EEG scans are sometimes used to check for abnormalities in the nasal cavity, brain, or nervous system.


Treatment

Phantosmia saline solution
Using a saline solution will rinse out the nasal passages and may relieve symptoms.

Treatment for phantosmia varies based on the underlying cause of the phantom smell.

People with chronic sinusitis or other long-lasting nasal inflammation can talk to a doctor about the best treatment options. Treating the underlying conditions should also address the phantom smell.

If symptoms persist for more than a few days, doctors may first recommend simple treatments, such as using a saline solution to rinse out the nasal passages. This may help dislodge anything that is trapped in the nasal passages and relieve the symptoms.

Certain drugs may help people with long-lasting phantosmia control their symptoms:

  • anesthetic to numb the nerve cells
  • drugs to narrow blood vessels in the nose
  • steroid creams or sprays

In some cases, doctors may turn to oral drugs or even surgery to treat phantosmia. They do not always recommend surgery, as it may only work in specific cases, and surgery carries its own set of risks.

Outlook

Phantosmia is not usually a cause for concern, and it often clears up by itself.

It can also be a symptom of a more serious condition, so people experiencing phantom smells should see their doctor to check for underlying conditions or complications.

The best treatment will depend on the cause of phantosmia. In some instances, the symptoms clear up on their own with time or when the sinus or nasal sickness that caused them goes away. In other cases, phantosmia may be chronic or long-lasting.

Doctors will help a person identify the treatment that works best for them and may suggest other ways to minimize symptoms if possible.

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