common medical conditions such as nasal infections, nasal polyps, or dental problems can cause phantom smells. a phantom smell can also result from neurological conditions such as migraines, head injuries, strokes, parkinson's disease, seizures, or brain tumors. it can also be a symptom of certain mental disorders such as depression, bipolar disorder, intoxication or withdrawal from drugs and alcohol, or psychotic disorders. certain substances in the environment can also cause phantom smells. these include tobacco smoke, certain types of chemicals (e.g., insecticides or solvents), or radiation treatment for head or neck cancer.