- By Laurel Kelly
Consumer Health: What are olfactory hallucinations?
Hallucinations are sensory perceptions of things that are not present. These perceptions may be sights, sounds, smells or sensations on the skin. Causes of hallucinations include head injury, Parkinson's disease, Lewy body dementia, a brain tumor, schizoaffective disorder, temporal lobe seizure and a medication side effect.