Smelling nail polish remover when none is around usually points to one of two things: either your body is actually producing acetone (the main chemical in nail polish remover) and you’re catching it on your breath, or your brain is generating a phantom smell that has no physical source. The first explanation is metabolic, and the second is neurological. Both are more common than most people realize, and telling them apart matters because they point toward very different underlying causes.
Your Body May Actually Be Making Acetone
Nail polish remover smells like acetone because it largely is acetone. Your body also produces acetone naturally as a byproduct of fat metabolism. When your cells burn fat for energy instead of glucose, they generate molecules called ketone bodies, and one of those ketones is acetone. It’s volatile, meaning it evaporates easily, which is why it escapes through your lungs into your breath. Under normal circumstances the amount is tiny and undetectable. But when ketone production ramps up, breath acetone rises to levels you and the people around you can smell.
The most common reasons for elevated ketone production include uncontrolled or poorly managed diabetes, prolonged fasting, very low-carbohydrate diets, and heavy alcohol use. In type 2 diabetes, acetone is produced after enzymatic breakdown of another ketone body, acetoacetate, and blood levels of these ketones correlate with measurable increases in breath acetone.1PubMed Central. Blood Ketone Bodies and Breath Acetone Analysis and Their Correlations in Type 2 Diabetes Mellitus In healthy adults eating ketogenic meals, breath acetone climbs reliably as ketosis develops, rising roughly three and a half times over a twelve-hour period.2PubMed. Breath acetone is a reliable indicator of ketosis in adults consuming ketogenic meals If you’ve recently started a keto diet or skipped meals for an extended stretch, the acetone smell on your breath is a real chemical signal, not a trick of your senses.
The distinction matters. If the smell seems to come from your own breath or the air right around your face, and especially if you’ve been fasting, restricting carbs, or have a history of blood sugar problems, the likeliest explanation is that your body is producing more acetone than usual. This version is metabolic, not neurological, and the smell has a real physical source even though there’s no bottle of nail polish remover in sight.
When Your Brain Creates a Smell That Isn’t There
If the acetone smell doesn’t seem to be coming from your breath, and nobody around you can detect it, you may be experiencing phantosmia, the perception of an odor without any external source. Think of it as a smell hallucination. The brain’s olfactory processing centers fire in a way that produces a vivid sensory experience, but there’s nothing in the air triggering it. Phantosmia can produce many different smells, with chemical or burning odors being among the most commonly reported.
Phantosmia is distinct from parosmia, which is the distortion of a real smell into something different. With parosmia, there is an actual odor source, but your brain misinterprets it. With phantosmia, the smell appears out of nothing.3PubMed Central. Parosmia and Phantosmia: Managing Quality Disorders A survey of over two thousand people with olfactory disorders found that about 11 percent experienced phantosmia alone, while another 16 percent experienced phantosmia alongside parosmia. Phantosmia was more common in middle-aged adults and was more likely to follow head trauma than parosmia was.4PubMed Central. Prevalence and correlates of parosmia and phantosmia among smell disorders
The causes of phantosmia range widely, from infections and traumatic brain injury to psychiatric conditions. That breadth is part of what makes it tricky: the same symptom can originate in very different parts of the body or brain, and treatment depends heavily on figuring out which one applies to you.
COVID and Post-Viral Smell Distortions
COVID-19 brought phantom smells into mainstream awareness. If your unexplained acetone smell started during or after a respiratory infection, a post-viral mechanism is one of the more likely explanations. In a large study of people who developed smell disorders after COVID, about 37 percent reported phantom smells. The probability of experiencing phantosmia was higher when the smell disturbance fluctuated rather than staying constant, lasted longer, and involved partial rather than total loss of smell. Women were also significantly more likely to report phantom smells than men.5PubMed Central. Phantom smells: a prevalent COVID-19 symptom that progressively sets in
What seems to happen is that the virus damages olfactory nerve cells in the nasal lining. As those cells regenerate and rewire, the signals they send to the brain can be garbled, producing phantom odors or distorted versions of real ones. For many people the phantosmia is temporary, fading as nerve recovery progresses. But in some cases it lingers for months or longer, and the timeline is hard to predict for any individual. COVID is far from the only virus that can cause this; influenza and other upper respiratory infections have long been associated with post-viral smell dysfunction, which was already the most common trigger for parosmia before the pandemic.
Medications That Can Alter Smell Perception
Certain prescription drugs are associated with an increased likelihood of phantom odor perception. A study of U.S. adults found that among people sixty and older, those taking diabetes medications, cholesterol-lowering agents, or proton pump inhibitors had roughly 74 to 88 percent greater odds of reporting phantom smells compared with people not on those medications.6PubMed Central. Prescription Medication Use and Phantom Odor Perception Among US Adults The mechanism isn’t fully pinned down for every drug class. Some medications may affect olfactory receptor turnover, some may alter neural signaling, and some may indirectly change body chemistry in ways that shift what the nose detects.
If you started smelling something strange shortly after beginning or changing a medication, it’s worth mentioning to your doctor. This doesn’t necessarily mean the drug is causing harm, but the association is strong enough in older adults to warrant at least a conversation about whether a medication change could resolve the symptom.
Neurological Conditions and Phantom Odors
Phantom smells can sometimes be an early sign of a neurological condition. In Parkinson’s disease, olfactory dysfunction affects an estimated 65 to 90 percent of patients, and some of those patients specifically report perceiving odors that have no external source.7PubMed Central. Phantosmia in Parkinson’s Disease: A Systematic Review of the Phenomenology of Olfactory Hallucinations Smell loss in Parkinson’s often precedes motor symptoms by years, so a persistent phantom smell in someone with no other explanation could, in rare cases, be an early marker. This shouldn’t cause panic, as most phantom smells are not signs of neurodegeneration, but it’s part of the diagnostic picture a neurologist would consider.
Temporal lobe epilepsy is another neurological condition that can produce olfactory hallucinations. Seizure activity in the temporal lobe, which houses much of the brain’s smell-processing architecture, can trigger brief, vivid smell experiences including chemical or perfume-like odors. One case involved a woman whose family noticed behavioral changes alongside her reporting the smell of perfume and aftershave that nobody else could detect, ultimately traced to temporal lobe epilepsy.8PubMed Central. Psychosis in temporal lobe epilepsy: atypical presentation Epilepsy-related smell hallucinations tend to be brief and episodic rather than constant, which can help distinguish them from other causes.
Head trauma is another recognized trigger. Injury to the brain can damage the olfactory bulb, the structure that receives signals from smell receptors, and subsequent neuroinflammation may worsen the deterioration over time. Animal research has shown that traumatic brain injury leads to significant olfactory bulb shrinkage that correlates strongly with smell deficits persisting at least twelve weeks after injury.9Mary Ann Liebert, Inc., publishers. Minocycline restores olfactory bulb volume and olfactory behavior after traumatic brain injury in mice In humans, the pattern of phantosmia following head trauma is consistent with damaged nerves sending disorganized signals as they attempt to heal.
Anxiety and Psychiatric Triggers
Phantom smells aren’t always rooted in physical damage. Anxiety and stress can generate olfactory hallucinations, though this is underrecognized. Case reports describe patients whose first and only symptom of an anxiety disorder was a persistent phantom smell, with no identifiable physical source and no abnormalities on brain imaging.10PubMed Central. First-episode olfactory hallucination in a patient with anxiety disorder: A case report More familiar psychiatric conditions like schizophrenia can also produce olfactory hallucinations, though these typically come with other symptoms that make the diagnosis more apparent.
The connection between anxiety and phantom smells may involve heightened sensory processing. When you’re anxious, your brain is on high alert for threats, and the olfactory system is deeply wired into the brain’s threat-detection circuitry. In evolutionary terms, smell was one of the primary ways animals detected danger in the environment, from fire to predators to spoiled food.11PubMed Central. The mysterious sense of smell: evolution, historical perspectives, and neurological disorders A brain in an anxious state may lower the threshold at which it generates a smell signal, essentially manufacturing a false alarm. Chemical smells like acetone are the kind of odor that would signal danger in a natural environment, so it makes some intuitive sense that an overactive threat system would land on that type of phantom rather than, say, the smell of flowers.
Environmental Exposures and Heightened Sensitivity
Sometimes the explanation is simpler and more external than you’d expect. Olfactory neurons sit in a uniquely exposed position: they’re located in the lining of your nasal cavity, in direct contact with whatever you breathe in, making them vulnerable to damage from airborne chemicals.12PubMed Central. Toxin-induced chemosensory dysfunction: A case series and review Occupational exposure to compounds like formaldehyde and certain metal dusts involving cadmium, chromium, or nickel has been linked to olfactory dysfunction.13PubMed Central. Olfactory dysfunction revisited: a reappraisal of work-related olfactory dysfunction caused by chemicals That dysfunction can include both reduced ability to smell and, paradoxically, phantom smells.
There’s also the possibility that trace amounts of acetone or similar volatile organic compounds are genuinely present in your environment at levels too low for most people to notice but within your detection range. Acetone has a wide odor detection threshold, ranging from about 20 to 400 parts per million depending on the individual and testing conditions.14PubMed. An analysis of human response to the irritancy of acetone vapors That’s a twenty-fold range, meaning some people can detect acetone at concentrations far below what others would notice. Cleaning products, paint, adhesives, and certain plastics can off-gas acetone or acetone-like compounds at low levels. If you’re on the sensitive end of the detection spectrum, you might genuinely be smelling something that others around you cannot.
Habituation also plays a role here. Workers who are regularly exposed to acetone vapors show reduced sensitivity to the odor over time, while people without prior exposure remain much more sensitive. If you recently moved into a new space or started a new job, you may be picking up on volatile compounds that the people around you have long since stopped noticing.
Kidney and Liver Problems Can Change Your Breath
Advanced kidney disease is another metabolic cause worth knowing about. When the kidneys aren’t filtering waste products efficiently, certain volatile metabolites build up and escape through the lungs. Ammonia is the most recognized breath marker in chronic kidney disease, but other volatile organic compounds accumulate as well, and some patients describe an unusual chemical or solvent-like smell.15PubMed. Breath analysis of ammonia, volatile organic compounds and deuterated water vapor in chronic kidney disease and during dialysis Severe liver dysfunction can produce a similar effect through different waste products. These are not subtle conditions, as they generally come with other symptoms like fatigue, swelling, or changes in urination. But if you’re already being monitored for kidney or liver issues and notice a new chemical smell, it’s worth flagging to your medical team.
How Doctors Approach the Problem
If you bring this complaint to a doctor, expect them to work through a branching decision tree. The first split is whether the smell has a real source or is a phantom. Questions about diet, fasting, diabetes history, and carb intake help rule in or out a metabolic explanation. A simple fingerstick blood glucose and a urine dipstick for ketones can settle that question quickly.
If the smell appears to be a phantom, the workup broadens. Doctors look at medication history, recent infections (especially COVID or other respiratory viruses), head trauma, and neurological symptoms. A thorough ear-nose-throat examination can identify sinus infections or nasal polyps that might contribute. Brain imaging with MRI may be ordered to rule out structural lesions, tumors, or signs of temporal lobe epilepsy. In some cases, formal smell testing helps characterize the extent of olfactory dysfunction.
Treatment depends entirely on the underlying cause. If ketosis is producing the smell, adjusting diet or managing blood sugar resolves it. For post-viral phantosmia, olfactory training, which involves repeatedly sniffing a set of distinct odors to help retrain the nerve pathways, is one of the more evidence-supported approaches and carries no risk. For phantosmia that persists and significantly affects quality of life, more aggressive options have been tried. These have included topical anesthetics applied to the olfactory region, antipsychotic medications like haloperidol, and in refractory cases, surgical removal of the olfactory tissue responsible for the phantom signal.16PubMed Central. A case study of phantosmia cured by antibiotic treatment of an intranasal Pseudomonas stutzeri infection Surgery is a last resort and, obviously, permanently eliminates smell from the treated side.
When the Smell Comes and Goes
One of the more frustrating aspects of phantom smells is their intermittent nature. You may notice the acetone smell intensely for a few minutes, then it vanishes. It might return at certain times of day, in certain positions, or during periods of stress. This on-and-off pattern is actually consistent with how phantosmia typically behaves. In the COVID phantosmia data, the probability of experiencing phantom smells was higher when the underlying smell disturbance was fluctuating rather than constant.5PubMed Central. Phantom smells: a prevalent COVID-19 symptom that progressively sets in The intermittent quality doesn’t make the experience less real, but it can make it harder to pin down and harder to describe to a doctor.
If the smell appears mainly when you’re tired, hungry, or stressed, pay attention to those patterns. Fatigue and low blood sugar can push the body toward greater fat burning and modest ketone production even without a formal ketogenic diet. And as noted earlier, stress and anxiety can lower the brain’s threshold for generating phantom sensory signals. Keeping a simple log of when the smell appears, how long it lasts, and what you were doing or eating beforehand gives a clinician much more to work with than a vague report of “I keep smelling nail polish remover.”
How Common Phantom Smells Actually Are
If you’re worried that smelling things that aren’t there means something is seriously wrong with you, it helps to know that smell distortions in the general population are more common than most people assume. They don’t always signal disease. A survey-based study found that among people in the general population who had some form of parosmia, there was no meaningful difference in self-rated quality of life compared to people without smell distortions.17Scientific Reports. Olfactory distortions in the general population Many people experience brief, occasional phantom smells that resolve on their own and never indicate a serious condition. The presence of a phantom smell, by itself, isn’t a diagnosis. It’s a symptom that can mean many things, from the trivially benign to the medically significant, and the context around it is what determines how urgently it needs attention.