Smelling fire, smoke, or something burning when there’s no actual source is a type of olfactory hallucination called phantosmia. It affects roughly 5% of older adults, is more common in women, and in most cases traces back to something treatable or temporary. Burning rubber and burnt toast are among the most frequently reported phantom smells.
That said, the range of possible causes is wide, from a recent cold to a neurological condition, so the explanation depends heavily on what else is going on in your body. Here’s what could be behind it.
Why Your Brain Creates a Smell That Isn’t There
Your sense of smell depends on a thin layer of nerve tissue high inside your nose called the olfactory neuroepithelium. These specialized nerve cells send electrical signals to the brain, where they’re interpreted as specific odors. Phantosmia happens when something disrupts this system, either at the nerve level inside the nose or at the processing level inside the brain.
When the disruption is in the nose (a “peripheral” cause), the leading theory is that damage to the nerve lining triggers faulty regrowth. The new nerve connections fire incorrectly, sending signals the brain reads as a smell that doesn’t exist. When the disruption is in the brain itself (a “central” cause), the smell-processing region misfires on its own, generating a sensation without any input from the nose at all.
One clue to which type you’re dealing with: if the phantom smell is only in one nostril, it’s more likely a peripheral problem originating in the nose. If it seems to come from both sides or you can’t localize it, a central cause is more plausible.
The Most Common Causes
Upper Respiratory Infections and COVID-19
Colds, sinus infections, and especially COVID-19 are among the most frequent triggers. A viral infection can directly damage the smell-detecting nerve cells in your nose. As those cells heal and regenerate over the following weeks or months, the new wiring can misfire, producing phantom smells of smoke, chemicals, or burning. With COVID-19 specifically, phantosmia sometimes appears months after the initial infection, even after other symptoms have fully resolved. It can last days, weeks, or in some cases much longer.
Sinus Problems
Chronic sinusitis, nasal polyps, and structural issues inside the nose can all interfere with how odor molecules reach your smell receptors. Ongoing inflammation in the sinuses irritates the surrounding nerve tissue, which can produce phantom or distorted smells. If you have a history of sinus trouble, recurring congestion, or facial pressure, this is one of the more likely explanations.
Migraines
Some people experience phantom smells as part of a migraine aura, the sensory disturbances that precede or accompany a migraine headache. A burning or smoky smell that reliably shows up before a headache and disappears afterward fits this pattern. It’s the brain’s pain-signaling networks activating nearby smell-processing areas.
Head Injury
A blow to the head, even one that seemed minor at the time, can shear the delicate nerve fibers that connect the nose to the brain. Phantom smells after a concussion or head trauma are well documented and can appear immediately or develop later as the nerves attempt to repair themselves.
Neurological Causes Worth Knowing About
In a smaller number of cases, phantom fire or smoke smells point to something happening inside the brain itself. The area most commonly involved sits at the junction of the temporal and frontal lobes, a region called the piriform cortex. This spot is a crossroads for smell processing, and it’s also particularly prone to abnormal electrical activity in people with epilepsy.
Temporal lobe seizures can produce brief, vivid phantom smells, often described as burning, chemical, or sulfurous, as an “aura” just before or at the start of a seizure. Research shows that seizure activity in the temporal lobe reliably activates the piriform cortex, the nearby amygdala, and the insula, all of which are involved in interpreting smells. If your phantom smoke smell comes in sudden, short episodes lasting seconds to a couple of minutes, especially paired with a strange feeling of déjà vu, a rising sensation in your stomach, or a brief period of confusion or staring, a seizure-related cause should be evaluated.
Brain tumors, particularly those near the olfactory groove at the base of the skull, can also produce phantom smells. This is uncommon, but it’s one reason doctors take new-onset phantosmia seriously. Tumors in this area may also cause gradual loss of smell on one side, vision changes, or headaches that worsen over time.
Phantosmia can occasionally be an early marker of neurodegenerative conditions like Parkinson’s disease or Alzheimer’s disease. Changes in smell (both phantom smells and a declining ability to identify real ones) sometimes precede other symptoms by years. This doesn’t mean a phantom smell predicts these conditions. It means doctors consider them as part of a thorough workup, especially in older adults with other subtle cognitive or motor changes.
Other Contributing Factors
The full list of conditions linked to phantosmia is long. It includes hypothyroidism, certain medications, exposure to environmental chemicals or toxins, tobacco use, alcohol use, and a history of radiation therapy to the head or neck. Aging itself plays a role: the nerve cells responsible for smell naturally become less reliable over time, which can produce both phantom smells and a reduced ability to detect real ones. Psychiatric conditions are also considered during evaluation, as olfactory hallucinations can occur alongside certain mental health disorders.
How Doctors Evaluate Phantom Smells
If a phantom burning smell persists, recurs, or comes with other neurological symptoms, the evaluation typically starts with a thorough ear, nose, and throat exam, including a look inside your nasal passages with a small camera (nasal endoscopy). This helps rule out polyps, masses, or significant inflammation.
Smell testing is a standard part of the workup. The most widely used tool is a scratch-and-sniff test that asks you to identify a series of odors. This establishes whether your overall sense of smell is intact or impaired, which helps narrow the list of causes. A neurological exam checks cranial nerve function and screens for signs of increased pressure inside the skull, such as swelling at the back of the eye.
Imaging comes next when the clinical picture warrants it. A CT scan of the sinuses looks for structural problems, polyps, or masses. An MRI is used when a brain tumor, abnormal anatomy, or other intracranial cause is suspected, particularly if the phantom smell is on one side, if there are other neurological symptoms, or if the pattern doesn’t match a straightforward diagnosis.
What Helps It Go Away
Treatment depends entirely on the underlying cause. Post-viral phantosmia, including cases tied to COVID-19, often resolves on its own as the damaged nerve tissue finishes regenerating. This can take weeks to months, and in some cases the timeline stretches longer. Saline nasal rinses are commonly recommended as a low-risk way to support nasal health during recovery.
When sinus disease is the driver, treating the inflammation or removing polyps typically reduces or eliminates the phantom smell. If temporal lobe seizures are responsible, controlling the seizures with medication stops the olfactory auras as well. For tumors, addressing the tumor itself is the priority.
In cases where phantosmia is limited to one nostril and clearly originating from the nasal lining, a procedure to remove the affected strip of olfactory nerve tissue is an option. Doctors can confirm the source by temporarily blocking the nostril with a local anesthetic: if the phantom smell disappears, the problem is localized and potentially correctable.
For many people, especially those whose phantosmia appeared after a cold or respiratory infection and who have no other concerning symptoms, the most accurate expectation is that it will fade gradually on its own. Persistent cases, those accompanied by headaches, confusion, vision changes, or seizure-like episodes, warrant a prompt medical evaluation to rule out the less common but more serious causes.