Smelling smoke when nothing is burning is a type of olfactory hallucination called phantosmia. It affects roughly 6.5% of U.S. adults, making it more common than most people realize. The phantom smell can come and go or linger for days, and it has a wide range of causes, from sinus problems and viral infections to migraines and, less commonly, neurological conditions.
What Phantosmia Actually Is
Phantosmia is the perception of a smell that has no source in your environment. Unlike parosmia, where a real smell gets distorted (coffee suddenly smells rotten, for example), phantosmia creates an odor out of nothing. Your brain generates the signal on its own, without any odorant triggering it.
The phantom smells are almost always unpleasant. Tobacco smoke is one of the most commonly reported, along with burning rubber, burnt toast, garbage, chemicals, and metallic odors. Some people smell it constantly; others get brief episodes lasting seconds to minutes. The pattern and duration often point toward the underlying cause.
Sinus and Upper Respiratory Causes
The most common triggers are problems in the nose and sinuses. Sinus infections, nasal polyps, and lingering inflammation from an upper respiratory infection can damage the thin layer of smell-detecting tissue high inside your nasal cavity. When that tissue heals, nerve fibers sometimes reconnect incorrectly, sending garbled signals to the brain that register as phantom smoke or burning.
This “faulty rewiring” mechanism explains why phantom smells often show up weeks after a cold or sinus infection rather than during the illness itself. The initial damage may go unnoticed, and the erroneous signals only start once the nerves attempt to regenerate. Chronic sinusitis and allergies can also keep the olfactory lining irritated enough to produce ongoing phantom odors.
Post-COVID Phantom Smells
COVID-19 put phantosmia on the map for millions of people. The virus has a particular affinity for olfactory nerve cells, and the resulting damage can produce both loss of smell and phantom odors during recovery. One study found that 8% of patients still reported qualitative smell disturbances like phantosmia two years after infection.
Recovery timelines vary widely depending on how severe the initial smell loss was. In people who lost their sense of smell completely, phantom and distorted odors lasted a median of about 406 days. Those with only partial loss recovered faster, with a median around 217 days. People whose overall smell function stayed normal but who developed phantom odors typically resolved within about 62 days. A large prospective study tracking patients over nearly two years found that qualitative smell problems rose from 23% at around 100 days to 30% at 244 days before dropping to just 1% by 721 days, suggesting that most post-COVID phantosmia does eventually resolve, even if it takes time.
Migraines and Olfactory Auras
If the phantom smoke smell arrives shortly before or during a headache, it may be a migraine aura. Olfactory auras are considered rare, but researchers believe they’re significantly underreported because neither patients nor doctors typically think of smell as part of a migraine.
The pattern is distinctive. The smell usually appears minutes to hours before the headache, often described as cigarette smoke, burning trash, or gas. In a study of 11 migraine patients with olfactory auras, the phantom smell lasted anywhere from 3 to 5 minutes up to 24 hours before the headache began. One patient reported smelling gas 60 to 180 minutes before each migraine. In rarer cases, the phantom smell can outlast the headache itself. One documented patient smelled cigarette smoke from the start of her migraines through 3 to 7 days after the pain resolved, a pattern not previously described in the medical literature. If you notice that phantom smoke consistently accompanies your headaches, it’s worth mentioning to whoever manages your migraines.
Neurological Causes
Phantom smells that occur in brief, intense bursts, especially if accompanied by a spacey or “zoned out” feeling, lip smacking, or a sense of déjà vu, can be a sign of temporal lobe epilepsy. The characteristic smell in temporal lobe seizures is often described as burning leather, though burning rubber and smoke are also reported. These episodes are typically short, lasting seconds to a couple of minutes, and feel involuntary and abrupt.
Persistent phantosmia in the absence of visual or auditory hallucinations raises particular suspicion for temporal lobe epilepsy. Brain tumors, head injuries, and certain neurodegenerative conditions can also produce phantom odors, though these are far less common than sinus-related or post-viral causes. Olfactory hallucinations can occasionally appear as a symptom of psychosis, but in most cases the cause is organic rather than psychiatric.
Who Gets Phantosmia More Often
A national survey published in JAMA Otolaryngology found that women report phantom odors at higher rates than men. Lower income and lower education levels were also associated with higher rates of phantosmia, possibly reflecting differences in exposure to environmental toxins, access to healthcare for sinus conditions, or other underlying health disparities. The overall 6.5% prevalence means that roughly 1 in 15 adults has experienced this at some point.
How Phantom Smells Are Evaluated
Doctors typically start with a detailed history: when the smell started, how long each episode lasts, whether it’s in one nostril or both, and whether anything makes it better or worse. A few characteristics can help narrow the cause. Phantom smells that can be temporarily relieved by saline nasal rinses, that seem to come from one side of the nose, or that are triggered by other smells tend to originate in the nasal lining rather than the brain. Smells that arrive in sudden, brief bursts with other unusual sensations point more toward a neurological source.
Depending on the suspected cause, evaluation may include nasal endoscopy to look for polyps or inflammation, a CT scan of the sinuses, or an MRI of the brain to check for structural problems. If epilepsy is suspected, an EEG (a test measuring brain electrical activity) is the standard next step.
Treatment Options
Treatment depends entirely on what’s driving the phantom smell. For sinus-related phantosmia, saline nasal rinses (using a neti pot or squeeze bottle) are a simple first step that some people find genuinely helpful. Treating the underlying sinus condition with nasal steroids or antibiotics can resolve the phantom smell as the olfactory lining heals.
For post-viral phantosmia, including post-COVID cases, the primary approach is time. Most cases improve gradually over months, though smell training (repeatedly sniffing specific essential oils to retrain the olfactory system) is sometimes recommended to speed recovery.
When migraines are the cause, standard migraine prevention strategies often reduce the olfactory auras as well. Medications originally designed for seizure prevention or nerve pain have shown success in treating phantosmia in some cases. For the small number of people with severe, persistent phantosmia that doesn’t respond to any medical treatment, surgical options exist that involve disrupting the olfactory nerve fibers on the affected side, though this is a last resort that sacrifices some smell function permanently.
One useful clue for distinguishing less worrisome phantosmia from something that needs urgent attention: brief, isolated phantom smells without other neurological symptoms (no confusion, no limb jerking, no vision changes, no memory gaps) are far more likely to be sinus-related or post-viral. Phantom smells paired with any of those additional symptoms warrant prompt evaluation.