Smelling cigarette smoke when no one is smoking is known as phantosmia, a condition in which you perceive smells that are not actually present. Before considering a medical cause, check for possible sources of smoke, as tobacco odors can linger on clothing, furniture, and walls, or enter your home from neighboring areas through ventilation.
Phantosmia is often associated with nasal or sinus conditions, such as the common cold, flu, COVID-19, chronic sinusitis, or nasal polyps. After a respiratory infection, particularly COVID-19, some people may also experience parosmia, a condition in which real odors are perceived differently, sometimes smelling like cigarette smoke or something burning.
Less commonly, phantom smells may be associated with head injuries, migraines, temporal lobe seizures, stroke, Parkinson's disease, psychiatric conditions, or, in rare cases, a brain tumor.
Seek emergency medical care immediately if the smell occurs along with symptoms such as weakness, difficulty speaking, confusion, a sudden severe headache, or loss of consciousness.
If the smell occurs frequently, persists, or is accompanied by other symptoms, consult your primary care provider or an ear, nose, and throat (ENT) specialist. Depending on your symptoms, you may also be referred to a neurologist for further evaluation.