Phantosmia

A simple explanation

You smell something burning. You check the stove. The stove is off. You check the toaster, the wires, the next room. Nothing. You step outside. The smell goes with you. You come back in. It is still there. Whatever is producing this smell is not in the environment. It is in your olfactory system, which has composed a fully felt odour from internal signal alone.

Phantosmia is the perception of a smell that has no source. The smell is real as experience. The thing producing it is not in the air.

An everyday example

You wake up with the faint smell of smoke in your nose. By the time you have made coffee, the smoke has become more chemical, like burning plastic. You ask your partner if they smell it. They do not. You open every window. The smell persists in patches across the day, sometimes faint, sometimes intense, sometimes triggered by other smells, sometimes arriving on its own. By the evening, you cannot tell whether you are still smelling it or whether you are remembering smelling it.

You sleep poorly. The next morning the smoke is back.

Why does this happen?

Because olfaction, like vision and hearing, is partly composed. Olfactory neurons in the nose detect molecules; signals travel via the olfactory bulb to the piriform cortex and onward to the amygdala and entorhinal cortex. The system maintains predictions about what should be smelled here, and like other perceptual systems it can produce a percept from internal activity alone — particularly under load.

The causes are many. Stress and fatigue can tilt the system. Migraine often produces olfactory aura. Post-viral changes (including post-COVID) can produce both parosmia (distorted smells) and phantosmia. Sinus inflammation, certain medications, neurological conditions, and dental issues are all on the differential. The Threat System's tilt toward unpleasant content — most phantom odours are burnt, chemical, metallic, or rotten — is consistent with a system biased toward detecting threat-relevant signals first.

The behavioral loop

A loop that hides because the smell is genuinely felt:

1. Load or trigger — fatigue, stress, illness, migraine prodrome, hormonal shift, or environmental cue.
2. Olfactory system tilt — predictions become weighted enough to produce internal signal as percept.
3. Phantom smell arrives — usually unpleasant, often persistent, sometimes triggered by ordinary smells.
4. Source search — you check stoves, wires, drains, fabrics, other people; nothing is found.
5. Threat verdict — the System classifies the unfindable smell as either internal pathology or environmental danger.
6. Somatic mobilisation — anxiety, vigilance, sleep disruption, repeated checking.
7. Residue — trust in olfactory perception erodes; the smell often persists for hours or days.
8. Re-entry — the next episode arrives with a lower threshold and a higher anticipatory load.

Emotional drivers

The feelings layered onto the percept:

• Concern about what the smell signals — neurological problem, environmental hazard, hidden fire.
• Frustration at being unable to verify or terminate the experience.
• Embarrassment at asking others to confirm a smell that no one else perceives.
• Quiet exhaustion from the persistent, unpleasant background of the percept.

What your nervous system does

The olfactory bulb maintains tonic activity even in the absence of stimulation; under normal conditions this activity is below the threshold of perception. Under load — stress, fatigue, migraine, post-viral changes — the threshold can drop, and tonic activity is read as percept. The piriform cortex composes the experience using existing odour templates, which is why phantom smells tend to land on familiar categories. The amygdala adds the affective weight, which is why the templates the system reaches for skew unpleasant.

The DojoWell interpretation

Phantosmia is what happens when the Threat System's olfactory prediction layer produces a percept from internal signal. The original system was orientation — the legitimate need to detect dangerous or important smells early. The substitute is an imagined odour: a fully felt percept that has no environmental source.

The deposit is low because the smell carries no information about the actual environment. The residue is moderate to high — the smell is unpleasant, often persistent, and erodes trust in perception. The effort is high because the olfactory system continues producing the percept across hours or days without your participation.

This is a domain where the work is less about practice and more about pattern. Brief, occasional phantom smells under clear load conditions are a common edge of the predictive olfactory system. Persistent, recurrent, or distressing phantosmia is clinical information. Phantom smells with unilateral character, accompanied by other neurological symptoms, or arising suddenly without obvious cause warrant medical attention.

How do I work with this?

You do not argue with the smell. You document it, you address load conditions, and you decide whether the pattern warrants a clinical conversation. Most phantosmia is benign and self-limiting. Some of it is information that needs a clinician's eyes.

Practical steps

1. Log the episodes. Date, time, duration, character of the smell, what preceded it, what eased it. Two weeks of log is a useful conversation with a clinician.
2. Address load conditions. Sleep, hydration, stress, dental hygiene, sinus health. Many phantom smells reduce when load reduces.
3. Do not over-clean the environment. Aggressive cleaning, candles, and air fresheners often worsen the experience by adding stimulus the system can build on.
4. Use neutral smells as anchors. Coffee beans, citrus peel, or a familiar tea can re-orient the olfactory system briefly and sometimes interrupt a phantom episode.
5. Talk to a clinician for pattern, not for single episodes. Persistence, change in character, unilateral perception, or accompanying neurological symptoms are clinical signals. The conversation is the work.

Reflection questions

• What conditions reliably precede your phantom smells, and what does that say about your current load?
• How has the experience changed your trust in your own perception more broadly?
• What does the Threat System seem to be defending against when the phantom smell is most intense?
• Where would the cost of waiting on a clinical conversation be higher than the cost of having one?

Frequently Asked Questions