Phantosmia is the medical word doctors use when a person smells something that is not actually there. The smells vary from person to person but are usually unpleasant, such as burnt toast, metallic, or chemical smells.

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Phantosmia is also called a phantom smell or an olfactory hallucination. Causes include problems with the nose, such as sinusitis, or conditions of the nervous system or brain, including migraine, stroke, or schizophrenia.

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.

This article explains everything to know about phantosmia, including its symptoms, causes, diagnosis, and treatment.

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 10-20% 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, in some cases, 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. However, 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.

There may be additional symptoms that go along with phantom smells depending on the underlying cause of the phenomenon or any comorbidities.

For example, research has shown that phantom smells can occur in people of younger age or people who also have symptoms of stress and anxiety in some cases.

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.

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

People with parosmia smell real-life smells, but the smells 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.

Parosmia can be disturbing, and symptoms can range from mild to severe. Severe parosmia may be debilitating. People with severe parosmia may have a hard time dealing with their symptoms, even temporarily.

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 for phantosmia varies based on the underlying cause of the phantom smell. This may include:

  • Allergies: Treatment can include steroids and allergy shots.
  • Smoking or exposure to toxins: A person may need to quit smoking and eliminate any known exposure to an unsafe chemical.
  • Drug reaction: A person may need to stop taking the drug that may be causing the phantom smell. Potential medications that may cause phantosmia include antidepressants and antibiotics. However, a person should not stop taking such medications without first consulting with their doctor. For example, a person may need to finish a full course of antibiotics to fight off an infection or slowly taper off an antidepressant.

If the phantom smells are a result of trauma to the brain or a viral infection, a person may only be able to wait for symptoms to resolve on their own as they heal.

A cause such as a brain tumor may involve surgery, as well as chemotherapy and radiation if the tumor is cancerous. A person who has a bacterial infection can take antibiotics.

Each neurodegenerative disorder that can cause phantom smells involves its own treatment guidelines and medications.

People with chronic sinusitis or other long lasting nasal inflammation can talk with 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 mucus from the nasal passages.

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

  • anesthetic to numb the nerve cells
  • steroid creams or sprays

In rare cases, doctors may turn to surgery to treat phantosmia. They do not always recommend surgery, as it may only work in specific cases such as dislodging inflamed mucus or polyps. Surgery also carries its own set of risks.

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.

How common is phantosmia?

Research shows phantosmia may affect as many as 11% of people.

How do I know if it is a real or phantom smell?

In some cases, people may believe they are noticing a phantom smell when they may instead be noticing a real but unexpected smell. If a person has changed any of their skin or hygiene products or has been exposed to any new materials, products, or packaging, they may be experiencing a real smell.

In addition, when a person installs a new air-conditioning unit, heater, or air filter, they may still be exposed to chemicals from the factory that produced them.

Can COVID-19 cause phantosmia?

Though COVID-19 is known for causing problems with a person’s sense of taste, its impact on a person’s sense of smell has not been widely described. However, research shows that in rare cases, the virus may cause phantom smells.