What Is Phantosmia?

Phantosmia is a condition that causes you to smell odors that are not there. It’s a type of olfactory hallucination. The perceived odors may be constant or come and go. 

Phantosmia has several possible causes, including inflamed sinuses, an upper respiratory infection, a head injury, a brain tumor, medication side effects, and Parkinson’s disease. It may affect your quality of life as well.

This article will provide an overview of phantosmia, including the causes and possible treatment options.

Phantosmia Symptoms

Individuals with phantosmia smell unpleasant odors that are not present. Common scents with phantosmia include:

• Burning rubber
• Burnt food
• Chemical smell
• Spoiled food 
• Rotten eggs (hydrogen sulfide)
• Garbage 
• Strong perfume
• Body odor 
• Gas smell
• Cigarette smoke
  

Phantosmia Causes

Phantosmia occurs when there is a problem with a person's olfactory system. Typically, odors enter the nose and dissolve into the nasal mucus. Once dissolved, they are absorbed through the nasal mucosa and stimulate the olfactory receptors. This process is how our brains can identify odors. 

Common Causes

The most common cause of phantosmia is sinonasal conditions, which account for up to 52% to 72% of all olfactory disorders. Research shows that severe infection or inflammation of the sinuses results in more severe olfactory problems. Mild sinonasal conditions tend to cause only mild olfactory issues. 

Common causes of phantosmia include:

• Upper respiratory infection
• Allergic rhinitis (hay fever allergy)
• Rhinosinusitis (inflammation of the nasal passages and sinus cavities)
• Nasal polyps (growths in the nasal passages and sinuses)
• Head trauma
• Intracranial (skull) damage

Olfactory disorders like phantosmia may be an early sign of a neurodegenerative disease. Most individuals with Parkinson’s disease experience changes in their ability to smell and taste. Conditions that may cause phantosmia include:

• Mild cognitive impairment (early stage of loss of memory and thinking ability)
• Parkinson’s disease (progressive neurodegenerative brain disorder)
• Parkinsonism (a group of neurological conditions that impact movement)
• Alzheimer’s disease (progressive brain disorder that diminishes memory and thinking)
• Multiple sclerosis (MS) (potentially disabling condition that impacts the central nervous system)

Medication side effects are responsible for about 12% of all olfactory disorders. Fortunately, these side effects are usually reversible once the medication is stopped. Medicines that may lead to phantosmia include:

• Chemotherapy (cancer treatment)
• Angiotensin-converting enzyme (ACE) inhibitors (lowers blood pressure)
• Calcium channel blockers (used for hypertension and irregular heartbeats)
• Diuretics (water pills)
• Intranasal zinc (used to treat colds)
• Antimicrobials (antibiotics, antifungals)
• Antiarrhythmics (suppresses abnormal heart rhythms)
• Antithyroid agents (improve thyroid function)
• Antidepressants (used to treat depression)
• Anticonvulsants (used to prevent seizures)
• Lipid-lowering medications (lowers cholesterol)

Less Common

Less common causes of phantosmia include:

• Alcohol abuse
• Cocaine use 
• Exposure to environmental toxins
• Radiation
• Renal failure (kidney failure)
• Hepatic failure (loss of liver function)
• Type 2 diabetes
• Cancer
• HIV (human immunodeficiency virus)
• Brain injury
• Brain tumor
• Nutritional deficiencies
• Surgical complications from nasal surgery
• Pregnancy
• Hypothyroidism (underactive thyroid)
• Addison’s disease
• Cushing’s syndrome
• Lupus 
• Migraine aura 
• Psychiatric conditions including anorexia, major depressive disorder, bipolar disorder, and schizophrenia
  

When to See a Healthcare Provider

See a healthcare provider as soon as you suspect that you may be experiencing phantosmia. This condition may be caused by a serious medical problem, such as a brain tumor, and needs to be diagnosed and treated early. Your primary healthcare provider will likely refer you to a specialist such as an otolaryngologist (an ear, nose, and throat doctor, or ENT).

Diagnosis

To diagnose phantosmia, your healthcare provider will take a detailed history and perform a physical exam. It may be helpful to take notes before your appointment. Write down how long you have been experiencing problems with smell and any other present symptoms. Tell your practitioner if you have recently experienced any trauma to the head or nose. 

Other screening tools include:

• Three-item microencapsulated odor identification test
• Anterior rhinoscopy (examination of nasal cavities)
• Nasal endoscopy (procedure that uses a narrow tube with a camera and light attached to examine the inside of the nose and sinuses)
• Computed tomography (CT) of the sinuses and nose
• Magnetic resonance imaging (MRI) of the brain

Phantosmia Treatment

Treatment for phantosmia varies depending on the underlying cause. Possible treatment options include:

• Observation: About one-third of individuals with phantosmia will experience symptom improvement over time.
• Medications: Antipsychotics, antimigraine medicine, and antiseizure drugs can all be used to treat phantosmia.
• Surgery: Olfactory mucosa excision surgery may relieve phantosmia while preserving olfactory function.
• Other: Transcranial stimulation and topical cocaine application have been used to treat phantosmia.

Summary 

Phantosmia is a condition that causes you to smell odors that are not there. Phantosmia has several possible causes, including inflamed sinuses, upper respiratory infection, head injury, brain tumor, medication side effects, and Parkinson’s disease. Your healthcare provider may recommend a physical exam, a smell test, and imaging studies to diagnose phantosmia. Possible treatment options include observation, medications, and surgery. 

A Word From Verywell

Phantosmia is a relatively rare olfactory disorder that can significantly impact your quality of life. If you suspect you are smelling odors that are not there, talk with your healthcare provider. Treatments may be available to restore your smell and improve your quality of life.