Phantom smells, known medically as phantosmia, are olfactory hallucinations in which a person perceives an odor that has no external source. They are more common than most people realize and stem from a surprisingly wide range of causes, from leftover damage after a head cold to early signs of neurological conditions. The experience can be fleeting and harmless or persistent enough to disrupt daily life, and understanding what is happening in the nose and brain helps clarify when phantom smells deserve medical attention.
What Phantosmia Actually Is
Phantosmia is the perception of a smell when no corresponding odor molecule is present in the environment. It differs from parosmia, a related condition in which a real smell is present but your brain misidentifies it, making coffee smell like sewage or flowers smell like chemicals.1PubMed Central. Parosmia and Phantosmia: Managing Quality Disorders The two are sometimes lumped together under “qualitative olfactory disorders,” but they involve distinct patient profiles and characteristics.2The Laryngoscope. Comparison of Patient Characteristics and Olfactory Sensitivity for Trigger Odorants in Parosmia and Phantosmia With phantosmia, you could be sitting in a clean, odorless room and suddenly detect burning rubber or cigarette smoke. The smell is entirely generated by your own nervous system.
What Phantom Smells Tend to Smell Like
If you have ever smelled smoke in a room where nothing was burning, you experienced the single most commonly reported phantom odor. In a population-based study of older adults, smoky or burnt smells dominated, reported by about half of people who described their phantosmia. Far less common were moldy, metallic, rotten, perfume-like, floral, dusty, or cooked-food smells.3PubMed Central. Phantom Smells: Prevalence and Correlates in a Population-Based Sample of Older Adults The heavy skew toward unpleasant smells is worth noting. Most people with phantosmia are not hallucinating roses; they are smelling something burning, rotting, or otherwise off-putting. Researchers think this may reflect the brain’s bias toward detecting threats, since the neural pathways for danger-related odors are more easily activated.
For some people the phantom smell is consistent: the same burnt odor every time. For others it shifts unpredictably or arrives in clusters over days or weeks before disappearing. This variability can make the experience disorienting, especially when nobody around you notices anything.
Where the Signal Goes Wrong
Phantom smells can originate at two different points in the system, and the distinction matters for treatment.
In peripheral phantosmia, the problem is in the nose itself. Biopsies of olfactory tissue from people with phantosmia have shown a higher proportion of immature neurons compared to healthy tissue, along with tangles of disordered nerve fibers called intraepithelial neuromas.4JAMA Otolaryngology–Head & Neck Surgery. Long-term Follow-up of Surgically Treated Phantosmia Essentially, when the olfactory lining regenerates after an injury or infection, some nerve cells grow back incorrectly, firing spontaneous signals that the brain reads as real odors. Peripheral phantosmia tends to be intermittent, often worse on one side of the nose, and can sometimes be relieved by blocking the nostril on the affected side.5PubMed Central. Phantom smells: a prevalent COVID-19 symptom that progressively sets in
Central phantosmia, by contrast, originates in the brain. Hyperactive cells in the frontal, insular, or temporal regions generate an odor signal with no input from the nose at all.6PubMed. Distorted olfactory perception: a systematic review This type tends to be constant, affects both nostrils equally, and does not go away when you block your nose. It is the version associated with epilepsy, neurodegenerative disease, and certain psychiatric conditions. Figuring out which type you have is one of the first things a clinician will try to determine, because the treatment paths diverge sharply.
Post-Infectious Phantosmia and the COVID-19 Wave
Upper respiratory infections have long been one of the leading causes of olfactory dysfunction, and COVID-19 dramatically expanded awareness of the problem. Many people who lost their sense of smell during a SARS-CoV-2 infection found that when smell started to return, it came back wrong, sometimes in the form of phantom odors. Research into the mechanism suggests this arises from a mismatch in how olfactory sensory neurons rewire during recovery: different neurons heal at different speeds, and some may end up expressing altered receptor profiles.7PubMed Central. A follow-up on quantitative and qualitative olfactory dysfunction and other symptoms in patients recovering from COVID-19 smell loss
Interestingly, studies of COVID-related phantosmia found that the phantom smells did not always appear right at the beginning of the infection. In many patients, phantosmia set in progressively, sometimes weeks or months after the acute illness, as the olfactory system was attempting to rebuild.8PubMed Central. Phantom smells: a prevalent COVID-19 symptom that progressively sets in Several patients in one study reported that the phantom smell could be triggered by suggestion, for example, reading about a particular odor or talking about smells during a conversation. That hints at a central component even in cases where the initial damage was in the nose: once the brain’s smell circuits become sensitized, attention and expectation can trigger a false signal.
The good news is that post-infectious phantosmia often resolves on its own as the olfactory neurons finish regenerating, though “on its own” can mean months to well over a year. For a subset of people it becomes chronic.
Epilepsy and Olfactory Auras
A sudden, brief phantom smell that arrives with a wave of déjà vu, nausea, or a rising feeling in the stomach may not be a nose problem at all. It may be a seizure. Olfactory auras are a well-documented feature of temporal lobe epilepsy, occurring in roughly 13% of patients with temporal lobe seizure foci.9Annals of Neurology. Clinical features and ictal patterns in epileptic patients with EEG temporal lobe foci The smell is typically sudden, unpleasant, hard to describe, and lasts seconds to a couple of minutes before other seizure symptoms follow.
Neuroimaging of epilepsy patients who experience olfactory auras has repeatedly pointed to the mesial temporal structures, particularly the amygdala, as the likely origin of the phantom smell signal.10Epilepsia. Olfactory Auras in Patients with Temporal Lobe Epilepsy This makes anatomical sense: the amygdala sits at a crossroads between emotion processing and olfactory input and has a direct wiring connection to the olfactory bulb that bypasses the thalamus, a shortcut few other senses have. When abnormal electrical activity erupts there, the brain reads it as an odor.
If your phantom smells are brief, stereotyped (always the same smell), accompanied by other odd sensations, and happen in discrete episodes, it is worth mentioning to a doctor. An electroencephalogram can pick up temporal lobe seizure activity even when the episodes feel minor.
Phantom Smells in Migraine
Migraine auras are most famous for their visual effects, like zigzag lines and blind spots, but they occasionally produce phantom smells instead. This is rare enough that only a small number of detailed case series exist. In one study of 11 patients with olfactory hallucinations during migraine, the phantom smell arrived either just before or at the onset of headache pain and typically lasted three to ten minutes.11Cephalalgia. Scent of aura? Clinical features of olfactory hallucinations during a migraine attack (OHM) Nine of those patients smelled the same odor every time, and only about a fifth of their total migraine attacks included the phantom smell.
Even more unusual, phantosmia has been reported as a migraine aura without any headache following it at all, a phenomenon documented in only a handful of published cases.12Headache: The Journal of Head and Face Pain. Phantosmia and Migraine With and Without Headache Someone with this presentation might experience a sudden, strange smell lasting a few minutes and then nothing else. Without the headache to clue them in, they would have no reason to connect it to migraine, which is likely why the association is underreported.
Parkinson’s Disease and Early Warning Signs
Loss of smell is one of the best-known early markers of Parkinson’s disease, often appearing years before motor symptoms. Phantom smells in Parkinson’s are less discussed, but they may also show up early. Researchers have proposed phantosmia as a potential premotor manifestation of the disease, suggesting that qualitative smell distortions, not just the more commonly tested smell loss, deserve closer attention during the prodromal phase.13JAMA Neurology. Phantosmias and Parkinson Disease
Estimates of how common phantom smells are among Parkinson’s patients vary widely, from less than 1% to about 18%, depending on the study population and how the question was asked.14PubMed Central. Phantosmia in Parkinson’s Disease: A Systematic Review of the Phenomenology of Olfactory Hallucinations That range is frustratingly broad, and part of the reason is that many Parkinson’s patients already have reduced smell, so they may not notice or report a phantom smell against the backdrop of an already impaired sense. It remains an active area of research, and nobody is suggesting that a phantom smell means you have Parkinson’s. But in someone who also has other subtle symptoms like reduced sense of smell, constipation, or REM sleep behavior disorder, it becomes a piece of a larger puzzle.
Medications That Can Trigger Phantom Smells
Polypharmacy, taking many prescription medications at once, is an underappreciated contributor. A study of U.S. adults found that taking five or more prescription medications was associated with about 70% greater odds of perceiving phantom odors. Among adults over 60, three drug classes stood out individually: diabetes medications, cholesterol-lowering drugs, and proton pump inhibitors were each associated with roughly 74% to 88% higher odds of phantom smell perception.15PubMed Central. Prescription Medication Use and Phantom Odor Perception Among US Adults
This does not mean those specific drugs directly cause phantosmia; the relationship could be partly explained by the underlying conditions being treated or by the metabolic burden of processing multiple drugs simultaneously. Still, if phantom smells appeared around the time a new medication was added, it is a connection worth flagging with your prescriber. Drug-induced phantosmia sometimes resolves when the offending medication is adjusted.
How Phantosmia Affects Daily Life
The psychological toll of olfactory disorders is routinely underestimated. A U.K. survey of people with smell dysfunction found high rates of depression and anxiety, impaired eating experiences in the vast majority, and significant relationship difficulties. Phantosmia specifically affected more than one in five respondents.16Oxford Academic. The Impact of Olfactory Disorders in the United Kingdom Constantly smelling something rotten or burnt, with no way to escape it, can make meals unappealing, socializing uncomfortable, and sleep difficult. People often report that others do not take the complaint seriously, which adds isolation to the experience.
Safety is another concern. If you are accustomed to phantom burnt smells, you may stop reacting to real burning smells, which can blunt your alarm response to actual dangers like kitchen fires or gas leaks. This desensitization effect gets little attention but is a practical risk for anyone with persistent phantosmia.
Treatment Options
Treatment depends heavily on the underlying cause and whether the phantosmia appears to originate in the nose or the brain.
For peripheral phantosmia that does not resolve on its own, surgical excision of the olfactory mucosa has been studied as a last resort. In a systematic review, olfactory mucosa excision produced short-term improvement in ten of eleven patients.17International Forum of Allergy & Rhinology. Management of long‐lasting phantosmia: a systematic review The same review found 41 patients had been treated with various medications, including antipsychotics, antimigraine drugs, antiseizure medications, transcranial stimulation, and topical cocaine application. Evidence for any single drug remained thin and case-based. In one unusual report, phantosmia that had persisted for years was cured by antibiotic treatment of a bacterial infection discovered in the nasal cavity.18PubMed Central. A case study of phantosmia cured by antibiotic treatment of an intranasal Pseudomonas stutzeri infection That case underscores how idiosyncratic the causes can be.
When the cause is epilepsy, treating the seizures with standard antiepileptic medications typically eliminates the olfactory auras. When migraine is the driver, migraine-preventive therapy may reduce the frequency. For post-infectious phantosmia, time and patience are the most common prescriptions, supplemented in some cases by olfactory training.
Olfactory Training
Olfactory training involves repeatedly sniffing a set of strong, distinct odors, typically four at a time, for about 20 seconds each, twice a day, over several months. The practice has the strongest evidence base for post-infectious smell loss, but there are reasons to think it may help with phantosmia too. Research has shown that this kind of structured sniffing induces measurable changes in brain connectivity, essentially nudging the olfactory system to rewire in a more orderly way.19Neural Plasticity. Recovery of Olfactory Function Induces Neuroplasticity Effects in Patients with Smell Loss Because one leading theory of post-infectious phantosmia involves miswired neurons during regeneration, encouraging correct reconnection through repeated exposure to real odors has a logical basis.
The training is low-risk and inexpensive. Commonly recommended scent sets include rose, eucalyptus, lemon, and clove, though the specific odors matter less than consistency and daily repetition. Results are gradual and not guaranteed, but many clinicians now recommend it as a first-line approach for anyone with qualitative smell distortion after an infection.
When Phantom Smells Are Not Phantosmia
Before attributing a mystery smell to your nervous system, it is worth ruling out actual environmental sources. Carbon monoxide is odorless, but electrical problems in a home can produce faint burning smells from overheated wiring that only one person notices because they happen to be near the source. Sinus infections can generate foul odors that seem to come from nowhere because the source is inside your own nasal passages. Dental abscesses can create a persistent bad taste and smell that the person perceives as coming from the environment. And some strong cleaning products or mold sources are detectable to people with more sensitive noses long before others notice.
The clinical hallmark of true phantosmia is that the smell persists when you leave the environment entirely and when you block your nostrils, or that it appears in wildly different settings with no plausible common source. If the smell only happens in one room of your house, you probably have a house problem, not a nose problem.
Phantosmia in Psychiatric Conditions
Olfactory hallucinations also appear in a subset of psychiatric disorders, particularly schizophrenia, severe depression, and some forms of psychosis. In these contexts, the phantom smell sometimes carries personal meaning or is embedded in a delusional framework, which distinguishes it from the more mechanistic phantosmia caused by nasal nerve damage or migraine. The central mechanism is similar, hyperactive smell-processing regions in the brain, but the broader clinical picture is very different.20PubMed. Distorted olfactory perception: a systematic review
It is worth emphasizing that having a phantom smell does not imply a psychiatric condition. The vast majority of phantosmia cases have straightforward explanations like post-viral nerve damage or medication effects. But if phantom smells are accompanied by other perceptual changes, unusual beliefs, or significant mood disturbance, a more comprehensive evaluation is warranted.
The Historical Thread
The idea that phantom smells can signal brain pathology is not new. In the late 19th century, the neurologist John Hughlings Jackson described seizures originating near the uncinate region of the temporal lobe that featured olfactory hallucinations, coining the term “uncinate seizures.” His work brought the hippocampal formation into focus as a critical structure for both smell and memory.21PubMed. A memoir of olfaction That connection, between smell and the deepest, oldest parts of the brain, is part of why phantom odors have been recognized as neurologically meaningful for well over a century. Smell is wired into the brain differently from vision or hearing, with fewer relay stations and more direct access to emotional and memory centers. That architecture makes phantom smells both a uniquely vivid experience and a surprisingly useful diagnostic clue.