Contact allergy to citral and its constituents geranial and neral, coupled with reactions to the prehapten and prohapten geraniol

Abstract

Background: Citral is commonly used as a fragrance and flavor material and consists of the aldehydes geranial and neral. Citral is included in fragrance mix (FM) II. Geranial and neral have also been identified in autoxidation of geraniol, a fragrance compound present in FM I.Objectives: To study contact allergy to citral, geranial, and neral, and concomitant reactivity to oxidized geraniol and fragrance markers of the baseline series.Methods: A total of 1476 dermatitis patients with suspected allergic contact dermatitis were patch tested using geranial, neral, and citral, all 3.5% petrolatum (pet.) as well as geraniol 6.0% and oxidized geraniol 11% pet. in addition to the Swedish baseline series.Results: Frequencies of positive reactions to citral, geranial, and neral were 2.9%, 3.4% and 1.9%, respectively. Together, citral and geranial gave 4.2% positive patch test reactions in consecutive dermatitis patients. In patients with positive reactions to citral or its components, 25% to 34% reacted to FM II and 61% reacted to oxidized geraniol.Conclusions: Patch testing with citral, its components, or oxidized geraniol detects contact allergic reactions not detected using the baseline series. Patch testing with pure geraniol was shown to be of little value. Geranial and neral, although closely chemically related, are concluded to be separate haptens. K E Y W O R D Sallergic contact dermatitis,

A negative breakdown test in a fragrance mix I‐positive patient does not rule out contact allergy to its fragrance constituents

“…16 Lemongrass oil contains citral and geraniol, 16 and citral is a mixture of geranial and neral. 16,23 Geraniol acts as a prehapten and prohapten and is oxidized to geranial and neral. 23 Both, oakmoss and tree moss, contain atranol and chloroatranol as well as resin acids, which are also well-known allergens in colophonium.…”

“…16,23 Geraniol acts as a prehapten and prohapten and is oxidized to geranial and neral. 23 Both, oakmoss and tree moss, contain atranol and chloroatranol as well as resin acids, which are also well-known allergens in colophonium. 16,24 Eugenol is the main ingredient of clove oil.…”

“…Geraniol is a prehapten and prohapten to the stereosisomers geranial and neral. 23 Citral is a mixture consisting of two thirds geranial and one third neral. 23 Lemongrass oil contains 50%-80% citral and 1%-8% geraniol, depending on its provenance.…”

“…23 Citral is a mixture consisting of two thirds geranial and one third neral. 23 Lemongrass oil contains 50%-80% citral and 1%-8% geraniol, depending on its provenance. 16 These relationships explain the high co-reactivity to geraniol, citral, and lemongrass oil.…”

A spotlight on lime: a review about adverse reactions and clinical manifestations due to Citrus aurantiifolia

“…In addition to the lime peel oil, geraniol is also found in many other natural oils, such as rose and citronella oil. Citral is the main component of lemongrass oil but is also found in lime leaf and peel oil [ 14 , 15 ].…”