This post is a response by a doctor to a question one of our community members asked.
For the 2 weeks I smell something bad, like burnt. What could it be?
Dr Nitesh’s reply:
Sense of odour in the absence of real stimulus is called olfactory hallucination or phantosmia. Olfactory hallucination can occur in one or both the nostrils. Cacosmia or unpleasant olfactory hallucination are the most common and are often described as smell of something burnt or foul smell. It can occur spontaneously or can be triggered by deodorants, changes in air flow or noise. Olfactory hallucinations can deteriorate quality of life with poor oral intake as person experiences foul odour even while having meals. Olfactory hallucinations occur to malfunction of neurons which lead to transmission of incorrect signals to brain.
Olfactory hallucinations can be caused by multiple conditions. It is most commonly seen in women of age between 15 to 30 years. Pregnancy has also been associated with changes in perception of olfaction and gestation. It can occur due to conditions like nasal polyps (painless, non-cancerous growth on inner lining of your nose), nasal infections or dental issues. Olfactory hallucinations can also be caused by neurological conditions like migraine, stroke, head injury, seizure or tumour in brain. Involvement of temporal lobe of the brain usually leads to olfactory hallucinations. Tumour of the olfactory bulb called neuroblastoma can lead to olfactory hallucinations. These can also be as symptom of certain psychiatric disorders like alcohol intoxication, bipolar disorder or psychotic disorders. Olfactory hallucinations are also common symptoms with Parkinson’s disease.
Olfactory hallucinations can go away on its own but if hallucinations are due to some ailment, hallucinations will go away when the medical condition is resolved. An olfactory hallucination is a rare symptom and due to their rarity no clear guidelines are available for their management. Saline nasal spray provides immediate relief from the symptoms and can be repeated several times during a day. Nasal spray blocks the nostrils and hence alleviates the symptoms. Topical solutions are also available which anaesthetise the inner lining of the nose thereby providing relief from symptoms. Some studies have shown role of anti-depressants in phantosmia. Serotonin reuptake inhibitors like venlafaxine are the most common antic-depressant used for this purpose.