A persistent skunk-like smell with no actual skunk nearby has two broad explanations: either something in your environment is producing a sulfur-rich odor that your nose interprets as “skunk,” or your brain is generating a smell that does not exist outside your head. The second possibility has a name, phantosmia, and it is more common than most people realize. Sorting out which category you fall into matters, because the causes range from a neighbor’s habits to neurological conditions worth investigating.
Real Smells That Mimic Skunk
Before assuming something is wrong with your nose or brain, it is worth considering whether the smell is genuinely there but coming from a source you have not identified. Several common substances produce sulfur-based compounds that smell strikingly similar to skunk spray.
Cannabis is the most frequent culprit. The “skunky” quality of marijuana is not just a casual nickname. A 2021 study identified a previously unknown family of volatile sulfur compounds in cannabis, with one compound in particular, 3-methyl-2-butene-1-thiol, responsible for the characteristic smell.1PubMed Central. Identification of a New Family of Prenylated Volatile Sulfur Compounds in Cannabis Revealed by Comprehensive Two-Dimensional Gas Chromatography That compound belongs to the same chemical family as the thiols in actual skunk spray. If your neighbor smokes or grows cannabis, the smell can travel through shared walls, ventilation systems, and open windows. Many people who do not use cannabis themselves have never learned to distinguish its odor from an actual skunk, especially when the scent arrives faintly and intermittently.
Natural gas is another possibility. Natural gas itself is odorless, so utility companies add sulfur-containing chemicals called mercaptans, specifically compounds like tert-butylthiol and ethyl mercaptan, so that leaks become detectable by smell.2PubMed Central. Portable chemical detection platform for on-site monitoring of odorant levels in natural gas These mercaptans activate a specific human odorant receptor, OR2T11, which requires copper ions to respond strongly to these small thiols.3PubMed. Smelling Sulfur: Copper and Silver Regulate the Response of Human Odorant Receptor OR2T11 to Low-Molecular-Weight Thiols A tiny gas leak near your furnace, stove, or water heater can produce a low-level skunk-like odor that comes and goes. If you suspect this, leave the area and call your gas utility immediately; even small leaks are a safety hazard.
Sewer gas from a dried-out P-trap in a rarely used drain can also push hydrogen sulfide into a room. Dead animals in walls or crawl spaces, sulfur-based well water, and even certain mold growth can produce sulfurous smells that the brain easily files under “skunk.” The intermittent nature of these sources, stronger when HVAC systems cycle on, or when temperature changes cause expansion in pipes, can make them seem mysterious.
When the Smell Is Not Really There
If you have ruled out environmental sources and still keep smelling skunk, what you are experiencing may be phantosmia: the perception of an odor in the absence of any chemical stimulus.4PubMed Central. Parosmia and Phantosmia: Managing Quality Disorders This is different from parosmia, which is a distortion of a real smell (for instance, coffee smelling like gasoline). With phantosmia, there is genuinely nothing in the air to trigger the perception. Your olfactory system is firing on its own.
In a large population-based study of older adults, about 5% reported experiencing phantom smells. The phenomenon was more common in women, in people with higher vascular risk, and in those who also reported distorted smell perception.5PubMed Central. Phantom Smells: Prevalence and Correlates in a Population-Based Sample of Older Adults Interestingly, having a poor sense of smell overall was not connected to phantosmia in that study. You can have perfectly normal smell ability and still experience phantom odors.
Phantom smells tend to be unpleasant. Burning, chemical, smoky, and sulfurous are the most commonly described qualities. Skunk falls squarely into this category. The reason phantom smells lean negative is not fully understood, but it may relate to which populations of olfactory neurons are most easily excited when the system misfires, and the brain’s tendency to interpret ambiguous neural signals as threatening.
Post-Viral Smell Distortion
COVID-19 brought phantosmia into mainstream awareness. Many people who lost their sense of smell during infection later developed phantom smells as their olfactory system tried to recover. Research suggests that phantosmia during post-viral recovery is linked to the death and regeneration of olfactory receptor neurons. The prevalence of phantom smells in COVID patients tends to peak around eight weeks after infection, roughly the time frame in which the olfactory lining is regrowing and reconnecting with the brain.6PubMed Central. Phantom smells: a prevalent COVID-19 symptom that progressively sets in
COVID is not unique in this regard. Any upper respiratory virus that damages olfactory tissue can produce phantosmia during recovery. Among people with smell disorders more broadly, those whose problems followed a viral infection are among the most likely to develop both parosmia and phantosmia, and these distortions are most common in the three-to-twelve-month window after the initial smell loss.7PubMed Central. Prevalence and correlates of parosmia and phantosmia among smell disorders In most people, the phantom smells gradually fade as the neurons finish rebuilding, though this can take a year or longer. If you had a bad cold, flu, or COVID in the past several months and now keep catching whiffs of something sulfurous, your olfactory wiring may still be under construction.
Neurological Causes Worth Knowing About
Phantom smells can also be a signal from deeper in the nervous system. The brain’s smell-processing circuitry runs through structures like the piriform cortex, the amygdala, and the hippocampus, regions that are also involved in memory, emotion, and seizure activity.8PubMed Central. Olfactory Dysfunction and Limbic Hypoactivation in Temporal Lobe Epilepsy When these areas become overactive or irritated, phantom smells are one possible result.
Temporal lobe epilepsy is the most studied example. An olfactory aura, a sudden unexplained smell, sometimes described as burnt rubber, chemicals, or something “funny,” can precede or accompany a seizure. In a study of people with transient epileptic amnesia, over half had olfactory hallucinations as part of their clinical picture.9PubMed Central. On the nose: olfactory disturbances in Transient Epileptic Amnesia Some of these individuals experienced the phantom smell at times unconnected to obvious seizure episodes, which could easily leave someone wondering why they keep smelling something foul for no apparent reason. If your phantom skunk smell comes on suddenly, lasts seconds to minutes, and is accompanied by a feeling of déjà vu, confusion, or brief memory gaps, this is a pattern worth mentioning to a doctor.
Migraine is another neurological possibility, though much rarer. Phantosmia has been documented as a migraine aura, and in some cases, the phantom smell arrives without a headache following it.10PubMed. Phantosmia and Migraine With and Without Headache Only a handful of such cases have been reported in the medical literature, so this is not a common explanation, but it is one that people with a migraine history should be aware of.
Head Injuries and Damaged Wiring
Head trauma is an underrecognized trigger. The olfactory nerves are thin and fragile, passing through tiny holes in the bone at the top of the nose on their way to the brain. Even a relatively mild head impact can shear or damage them. Most patients are unaware that head injuries can cause both a loss of smell acuity and a subsequent onset of phantosmia.11The FASEB Journal. Smell Loss and Onset of Phantosmia are Critical Aspects of Head Injury Cognition The phantom smells typically emerge over time, often weeks to months after the injury, as damaged neurons attempt to regrow. The resulting signal is garbled, and the brain interprets it as a bad smell. Research points to diminished growth factors in the olfactory system and reduced levels of certain neurotransmitters as contributing mechanisms.
What makes post-traumatic phantosmia tricky is that the triggering injury does not have to be severe. A car accident, a sports collision, or even a hard fall can be enough. People often do not connect a head bump months ago with a strange smell appearing now, especially since the smell loss that typically precedes phantosmia can be subtle enough to go unnoticed.
Medications That Can Fool Your Nose
Certain prescription drugs are associated with phantom odor perception. A study using nationally representative data from U.S. adults found that among people aged 60 and older, those taking diabetes medications, cholesterol-lowering drugs, or proton pump inhibitors had roughly 75 to 90 percent higher odds of reporting phantom smells compared to non-users.12PubMed Central. Prescription Medication Use and Phantom Odor Perception Among US Adults The study was cross-sectional, so it cannot prove the drugs directly cause the phantom smells, but the association was consistent even after accounting for other health factors.
Some medications have more direct case evidence. Topiramate, a drug used for epilepsy and migraine prevention, has been linked to reversible phantosmia in case reports. In one documented instance, a patient developed olfactory hallucinations after starting topiramate, and the phantom smells disappeared entirely within two weeks of stopping the drug.13European Psychiatry. Topiramate-Induced Phantosmia: A Case Report on Reversible Olfactory Hallucinations in Epilepsy Treatment If your phantom skunk smell started around the same time as a new medication, that timing is worth flagging with your prescriber.
Anxiety, Stress, and Olfactory Hallucinations
Psychiatric conditions can also produce phantom smells, and not only in the dramatic ways people tend to imagine. Olfactory hallucinations are well-documented in schizophrenia and psychotic disorders, but they can also show up in anxiety. In one published case, a 66-year-old woman experienced gradually worsening olfactory hallucinations over nearly four years before being diagnosed with generalized anxiety disorder.14PubMed Central. First-episode olfactory hallucination in a patient with anxiety disorder: A case report The phantom smells were her primary symptom, not a side note to other psychiatric complaints.
The connection between anxiety and phantom smells is not well understood, but heightened autonomic arousal and altered neural processing in the limbic system are plausible pathways. Stress on its own may not generate a fully formed phantom smell, but in someone whose olfactory circuitry is already slightly unstable, perhaps from a past viral infection or age-related changes, chronic anxiety could tip the balance. If the smell tends to appear during high-stress periods or alongside other anxiety symptoms like rapid heartbeat, muscle tension, or a sense of dread, this is worth exploring.
Your Mouth as a Sulfur Factory
Here is a source of skunk-like smell that many people overlook entirely: your own mouth. The primary compounds behind bad breath are volatile sulfur compounds, including hydrogen sulfide and methyl mercaptan, the exact same class of molecule found in skunk spray and natural gas odorants. Certain oral bacteria, particularly those involved in periodontal disease, are potent producers of methyl mercaptan from the amino acid methionine.15PubMed Central. Methyl mercaptan production by periodontal bacteria
What makes this confusing is that you can sometimes perceive your own oral sulfur compounds retronasally, through the back of your throat into the nasal cavity, in a way that feels like you are smelling something in the room rather than tasting something in your mouth. This is especially likely if you have gum disease, a tooth abscess, post-nasal drip, or tonsil stones. The smell may come and go with eating, drinking, or even just swallowing. If no one else around you smells skunk but you catch it intermittently, and especially if you notice it more in the morning or when your mouth is dry, a dental check-up is a reasonable next step.
How Doctors Approach Phantom Smells
There is no single test for phantosmia. Diagnosis usually involves ruling out real environmental sources first, then assessing whether the smell perception matches any known pattern, such as post-viral recovery, medication timing, or seizure-related symptoms. An ear, nose, and throat specialist can examine the nasal passages for polyps, chronic sinusitis, or other structural issues that might contribute. If a neurological cause is suspected, imaging and possibly an electroencephalogram may be ordered.
Treatment depends entirely on the cause. Post-viral phantosmia often resolves on its own as the olfactory neurons finish regenerating, though smell training, repeatedly sniffing specific scents to help retrain the system, can accelerate the process. Medication-related cases may resolve when the drug is changed. Epilepsy-related phantom smells are managed by controlling the seizure disorder. For cases where no clear cause is found, treatment is less straightforward, with the focus shifting to managing the symptom itself.4PubMed Central. Parosmia and Phantosmia: Managing Quality Disorders Some patients find relief with saline nasal rinses or topical anesthetics applied to the olfactory cleft, though evidence for these approaches is limited.
When a Persistent Phantom Smell Deserves Urgent Attention
Most phantom smells are benign and temporary. But certain features warrant prompt medical evaluation rather than a wait-and-see approach. A phantom smell accompanied by confusion, memory lapses, or a sense of unreality could point to seizure activity. A phantom smell that started after a head injury, even a seemingly minor one, deserves neurological follow-up. A smell that only you perceive and that worsens progressively over weeks or months, rather than coming and going, is worth investigating to rule out a structural problem in the nasal cavity or brain.
If the smell comes with other new neurological symptoms, such as changes in taste, difficulty finding words, one-sided weakness, or visual disturbances, seek evaluation quickly. These combinations can point to processes that benefit from early treatment. For most people, though, a persistent skunk smell without other worrying symptoms is more likely to be a quirk of olfactory recovery, an environmental source they have not tracked down yet, or one of the milder triggers discussed above. Keeping a simple log of when the smell appears, what you were doing, and what medications or foods were involved can help a clinician narrow the possibilities considerably.