Phantosmia
Olfactory hallucination -- you perceive a smell that isn’t actually present in your environment. These phantom odors can appear in one or both nostrils and can come and go or remain constant.
While the smells are unique to each person, they are almost always unpleasant. People experiencing phantosmia frequently report smelling:
- Cigarette or wood smoke
- Burnt rubber or chemicals
- Rotting food or sewage
- Stale, metallic odors
Phantosmia vs. Parosmia:
It is often confused with parosmia, but they are fundamentally different:
Phantosmia: A smell is detected when nothing is there (a true hallucination).
Parosmia: An actual, physical odor is present in the room, but your brain distorts it into something else (e.g. a fresh cup of coffee suddenly smelling like gasoline).
Causes:
The issue usually stems from a misfire either in the nasal passages (peripheral) or within the brain’s processing centers (central). Signals travel from the nose up along the olfactory tract directly into the brain’s processing centers. When phantosmia occurs, it is typically triggered by one of two areas:
- Local Nasal Issues (Most Common): Chronic sinus infections, nasal polyps, allergies, or upper respiratory infections (like cold, flu or COVID-19) can damage or irritate the olfactory receptors in the nasal cavity, causing them to send faulty signals.
- Neurological Factors: Because the olfactory tract connects deeply into the brain, conditions like migraines, head injuries, temporal lobe seizures, or neurological changes can cause the brain to misinterpret signals or generate phantom smell on its own.
When to See a Doctor:
Most phantom smells are temporary and clear up on their own as the underlying sinus or viral issue resolves. However, because it can occasionally be a sign of a neurological condition, it is a good idea to consult a healthcare provider if the smells persist, worsen, or are accompanied by other symptoms like headaches, dizziness, or vision change.