Smelling burnt toast -- or other strange, random odors that are not actually present -- can in fact point to a medical issue, perhaps occurring as the body's way of telling a person that something is wrong. These phantom smells, also known as olfactory hallucinations or phantosmia, can result from a wide variety of conditions, many of which affect the brain, specifically the area of the brain
. that processes smells.People with seizure disorders such as epilepsy or temporal lobe seizures have reported instances of phantosmia prior to the onset of an event, and migraine sufferers may experience these phantom spells during the aura phase, which is a stage that precedes the actual headache. Other conditions that may cause olfactory hallucinations include Alzheimer's disease, Parkinson's disease, multiple sclerosis, brain tumors or cysts, head injuries and even sinus or brain infections. There are other reports of phantosmia occurring prior to cardiovascular events such as strokes or heart attacks.The smells that sufferers reportedly experience are typically unpleasant, including burning, rotting, chemical or sulfurous odors like rotting eggs. Since the human brain instinctively equates foul or stinky odors with danger, the brain may activate phantom smells that tend toward the odoriferous rather than pleasant ones as a warning sign.Since there are so many potential causes of olfactory hallucinations, it is a good idea to treat phantosmia as a warning of a potential problem and contact a physician if one often smells things that are not actually present, including burnt toast or other unpleasant odors. The doctor may order tests such as an MRI or CT scan to check for tumors or other causes of the hallucinations, but some patients never actually find out what causes their symptoms. The hallucinations may come and go for many years, disappearing for months only to reappear again.