Phantosmia: What is the medical condition where you smell gas?

September 28, 2025 •

3 min read

Phantosmia, the medical condition where you smell gas or other odors that aren't there, is a form of olfactory hallucination and makes up 10% to 20% of smell-related disorders. While often temporary, these phantom smells can signal a range of underlying health issues, from common infections to more serious neurological conditions.

Quick Summary

Phantosmia, also known as olfactory hallucinations, is the medical condition of smelling phantom odors, such as gas, that no one else can detect. The causes vary widely, ranging from sinus issues and head trauma to neurological conditions like migraines, epilepsy, and, in rare cases, brain tumors.

Key Points

Phantosmia is the official term: This condition is also known as olfactory hallucinations, where a person smells phantom odors that are not present.
Causes range from mild to serious: Triggers can include common infections like a cold or COVID-19, but also more serious conditions such as epilepsy, migraines, or head trauma.
Nasal and neurological issues are distinct: Phantosmia can result from problems in the nasal passages (peripheral) or the central nervous system (central), with the latter often being more persistent.
Differentiating from real gas is critical: If you smell gas, first ensure there isn't a real leak. Phantosmia symptoms are internal, while a real leak affects everyone.
Diagnosis requires professional evaluation: A doctor will perform an exam and may use imaging or other tests to determine the underlying cause and the appropriate treatment.
Treatment depends on the cause: Options range from managing infections to adjusting medications, or in neurological cases, using specific treatments for conditions like epilepsy.

What Is Phantosmia?

Phantosmia is the clinical term for perceiving a smell that has no external source. These phantom odors, often unpleasant like burning rubber or gas, can be experienced in one or both nostrils and may be constant or intermittent. While usually temporary and benign, phantosmia can sometimes indicate a more serious health concern.

Causes of Phantom Smells

Phantosmia can result from issues in the nasal passages (peripheral) or the central nervous system (central).

Nasal and Sinus Issues

Inflammation or abnormalities in the nasal cavity are common causes of phantosmia. Problems with the peripheral olfactory nerves, which send smell signals to the brain, can trigger phantom smells. Causes include upper respiratory infections, chronic sinus infections, nasal polyps, and allergic rhinitis.

Neurological Disorders

When phantosmia originates in the central nervous system, it tends to be more persistent and can affect both nostrils. Potential neurological causes include epilepsy (often as a seizure aura), migraines, head trauma, stroke, brain tumors, and neurodegenerative diseases like Parkinson's and Alzheimer's.

Other Contributing Factors

Other factors contributing to phantom smells include certain medications (antidepressants, antibiotics, blood pressure drugs), aging, psychiatric conditions like schizophrenia, and exposure to toxic chemicals.

Phantosmia vs. Parosmia

It's important to distinguish phantosmia from parosmia. Phantosmia is smelling something that isn't there (a hallucination), while parosmia is a distorted perception of a real smell, often experienced during recovery from viral infections like COVID-19.

Diagnosis and Treatment

Diagnosing the cause of phantosmia involves a physical exam and potentially tests like CT or MRI scans, EEG, or nasal endoscopy. Treatment is tailored to the underlying cause. This might involve treating infections or allergies, adjusting medications, or managing neurological conditions with specific therapies. Symptom relief for nasal causes may include nasal sprays or saline rinses.

Distinguishing a Phantom Smell from a Real Gas Leak

If you smell gas, always prioritize safety and assume it is a real leak until confirmed otherwise. Phantosmia is perceived only by the individual, may be intermittent or in one nostril, and can have associated health symptoms. A real gas leak can be smelled by others, is persistent, and can cause symptoms like dizziness and nausea. The table below offers a comparison:


Feature	Phantom Gas Smell (Phantosmia)	Real Gas Leak
Perception	Only perceived by the individual experiencing phantosmia.	Can be smelled by others in the vicinity, or detected by leak sensors.
Consistency	May come and go, often described as a faint or constant odor, sometimes only in one nostril.	Persistent odor that can increase in intensity as the concentration of gas rises.
Associated Symptoms	May be accompanied by other health issues like headaches, seizures, or post-infection symptoms.	Can cause physical symptoms like dizziness, nausea, headaches, and fatigue from low-level exposure.
Safety Action	If all safety checks pass, monitor symptoms and consult a doctor.	Immediately evacuate and contact your gas company or emergency services.

Living with Phantosmia

Managing phantosmia symptoms can include tracking occurrences, avoiding triggers, using saline rinses for nasal issues, and consulting an ENT specialist if symptoms persist.

Conclusion

What is the medical condition where you smell gas? Phantosmia, or phantom smells, can be caused by various factors, from minor infections to serious neurological conditions. The unpleasant smell of gas is a frequent report. While phantosmia can be concerning, an accurate diagnosis is crucial for effective treatment. Always prioritize safety in case of a real gas smell. Consult a healthcare professional for persistent phantom smells. For more information on smell disorders, visit the Mayo Clinic website.

Frequently Asked Questions

People with phantosmia most often report unpleasant odors, such as the smell of burning rubber, chemicals, or gas fumes. Less commonly, a person might experience pleasant phantom smells.

The duration of phantosmia varies. If caused by a temporary infection like a cold, the phantom smells usually go away within a few weeks as you recover. If the cause is a neurological issue, they can sometimes last for years.

Yes, a brain tumor, particularly in the areas that process smell, can cause phantosmia. However, this is a less common cause. It is important to see a healthcare provider to rule out any serious conditions.

While phantosmia is not typically a mental health condition itself, olfactory hallucinations can sometimes be a symptom of certain psychiatric disorders, such as schizophrenia. It is not, however, caused by anxiety.

Phantosmia is the perception of a smell that is not actually present. Parosmia, by contrast, is a distorted sense of smell where a real odor is perceived incorrectly, for example, smelling a pleasant scent as something foul.

Yes, phantosmia can be a side effect of certain medications. This is usually reversible once the medication is stopped, but you should only do so under a doctor's supervision.

If you smell gas, your top priority is safety. First, evacuate everyone from the property. Then, from a safe location, call your local gas company or the emergency services. Never assume it is a phantom smell until a professional has confirmed there is no leak.