Osmophobia and Odour-triggered Headaches – Review of the Literature and Main Research Centres

Abstract

There is an important relationship between odours and primary headaches. Patients may present osmophobia during headaches and odours may trigger headache attacks. This review aimed to describe the studies on osmophobia, odour-triggered headache, the main researchers and their research centres. Publications on the relationship between odours and primary headaches were searched in 193 sovereign countries and 48 dependent territories in all continents. We consulted the PubMed database and used the descriptors: "osmophobia in [name of the country or territory]"; "odours and headache in [name of the country or territory]" and "smell and headache in [name of the country or territory]". A total of 254 articles were found, but only 31 articles were considered relevant and composed this review. Of the 31 articles, 90.3% were cross-sectional studies, 6.5% case reports and 3.2% systematic reviews. All studies were performed on three continents: Europe (45.2%), America (32.2%) and Asia (22.6%). For the purpose of this study, North America and South America have been classed as one continent. No research was developed in Africa or Australia. More than 50.0% of the studies were conducted in Italy and Brazil. Only five authors published 38.7% of the studies. Osmophobia during headache attacks was investigated in 67.7% of studies, and odour-triggered headache in 19.3%. Studies on osmophobia and/or odour-triggered headache were carried out in several countries. They were useful in differentiating between migraine and tension-type headache. This could improve the accuracy of diagnosis of migraine compared to the current criteria.

Headache and Osmophobia in Gas Station Workers Exposed to Gasoline Odor

“…In primary headaches, headache attacks may be triggered by several factors, such as stress, eating habits, sleep deprivation, light stimuli, menstrual changes and odors, especially in migraine patients [1][2][3][4]. In addition, many patients complain of odor intolerance (osmophobia) both during headache attacks and in the pain-free period [5][6][7][8].…”

Migraine Improvement During COVID‐19 Pandemic – A Case Report on the Wonders of a Mask

“…Osmophobia is the fear, dislike, or aversion to odors; it occurs more frequently in primary headaches, mainly in migraine, with a variable reported frequency of 20-86%; 2 it has also been associated with more severe migraine intensity. 2 Several authors have pointed out osmophobia not only as very specific, but also a very insensitive element within the diagnosis of migraine, being rarely associated with another type of primary headache.…”

“…Osmophobia is the fear, dislike, or aversion to odors; it occurs more frequently in primary headaches, mainly in migraine, with a variable reported frequency of 20-86%; 2 it has also been associated with more severe migraine intensity. 2 Several authors have pointed out osmophobia not only as very specific, but also a very insensitive element within the diagnosis of migraine, being rarely associated with another type of primary headache. 2,3 Recently, a prospective study found that 28% of persons with migraine disease reported osmophobia exclusively during a headache attack without any associated symptoms, including nausea/vomiting or photo/phonophobia, suggesting that the inclusion of osmophobia in the International Classification of Headache Disorders-3 criteria for migraine would allow an increased diagnostic sensitivity by 9%; 3 however, this inclusion proposal remains a subject of debate.…”

“…2,3 Recently, a prospective study found that 28% of persons with migraine disease reported osmophobia exclusively during a headache attack without any associated symptoms, including nausea/vomiting or photo/phonophobia, suggesting that the inclusion of osmophobia in the International Classification of Headache Disorders-3 criteria for migraine would allow an increased diagnostic sensitivity by 9%; 3 however, this inclusion proposal remains a subject of debate. 2 Few studies have shown that odors may also trigger headache attacks, even in low concentrations and with odors that are commonly well tolerated by the general population. 2,3 Perfume fragrances are the most often reported triggers, particularly those with floral scent; 2 others include cigarette smoke, cleaning products, petroleum-derived products, or certain foods, in particular those with strong flavors and rarely alliaceous foods (like onions).…”

“…2,4 Transient receptor potential ankyrin 1, a nonselective cation channel expressed in sensory neurons, has also been implicated in the activation of the trigeminovascular system favoring central sensitization and cutaneous allodynia. 2 Furthermore, some authors reported that in migraine patients there is a smaller olfactory bulb volume suggesting that if osmophobia is an olfactory dysfunction, its presence may contribute to even more reduced bulb volume. 2 In summary, we report an uncommon case of a migraine triggered exclusively by odors, associated with osmophobia, including the infrequently reported onion scent, 4 that was successfully and unintentionally managed with a surgical face mask.…”