Phantosmia: What causes olfactory hallucinations?

An olfactory hallucination (phantosmia) makes you detect smells that aren't really there in your environment.

The odors you notice in phantosmia are different from person to person and may be foul or pleasant. You may notice the smells in one or both nostrils. The phantom smell may seem to always be there or it may come and go.

Phantosmia may be caused by a head injury or upper respiratory infection. It can also be caused by aging, trauma, temporal lobe seizures, inflamed sinuses, brain tumors, certain medications and Parkinson's disease. Phantosmia can also result from COVID-19 infection.

Talk to your health care provider if you have symptoms of phantosmia, so that they can rule out any serious underlying disorders that may be causing olfactory hallucination.

Parosmia is another smell disorder that's similar to phantosmia. But in parosmia a smell that's present in your environment is changed and doesn't smell as it typically would. Parosmia can occur with damage to the olfactory system. This can happen after a severe respiratory infection, including COVID-19.