Osmophobia: Definition and Clinical Significance
Osmophobia is an unpleasant perception of odors during a headache attack that are normally non-aversive or even pleasurable outside of attacks. 1
Clinical Definition
- Osmophobia represents a sensory hypersensitivity where patients experience intolerance to smells specifically during headache episodes, not between attacks 2, 1
- The phenomenon involves odors triggering discomfort or worsening symptoms during the headache phase, distinguishing it from general smell sensitivity 1
Most Common Offending Odors
The odors most frequently reported as triggering osmophobia include:
- Scents and perfumes (63.9-88% of patients) 2, 3
- Food odors (54.2-55.2% of patients) 2, 3
- Cigarette smoke (54.8-62.5% of patients) 2, 3
Diagnostic Significance
Osmophobia is highly specific for migraine and serves as a discriminating feature from tension-type headache. 2, 1
Prevalence by Headache Type
- Migraine without aura: 43-74% of patients report osmophobia during attacks 2, 1, 3
- Migraine with aura: 38.5-84% of patients experience osmophobia 2, 3
- Episodic tension-type headache: 0-43.3% (most studies show 0-14.5%) 2, 1, 3
- Cluster headache: 7-31.3% of patients 1, 4
Diagnostic Utility
- Osmophobia appears structurally integrated into the migraine history and should be considered a candidate criterion for migraine diagnosis 2, 1
- The symptom demonstrates "almost perfect" concordance when used alongside photophobia and phonophobia in diagnostic criteria (κ = 0.886) 4
- Proposed diagnostic criteria suggest requiring at least two of photophobia, phonophobia, or osmophobia instead of requiring both photophobia and phonophobia, which may increase diagnostic yield particularly in Asian populations 4
Temporal Characteristics
- Osmophobia begins 30 minutes before headache onset in approximately 22.7% of patients 3
- In 50% of patients, osmophobia occurs in all headache attacks; in 11.7%, it occurs in more than half of attacks 3
Associated Clinical Features
- Migraine patients with osmophobia score higher on anxiety and depression scales (HADS scores 15.6 ± 7.6 vs. 13.3 ± 7.8 in those without osmophobia, p < 0.001) 4
- Olfactory discrimination scores are significantly lower in migraine patients with osmophobia compared to those without osmophobia and healthy controls 5
- Threshold and identification scores are also reduced in migraine patients with osmophobia compared to controls 5
Clinical Context
Osmophobia is recognized as one of the migraine features in vestibular migraine diagnostic criteria, alongside photophobia and phonophobia, where at least one symptom during vestibular episodes supports the diagnosis 6