To Örebro University

Background: Citral is commonly used as a fragrance and flavour 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.

Patients and Methods: 1476 dermatitis patients with suspected allergic contact dermatitis were patch tested using geranial, neral and citral, all 3.5% pet., 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, 25‐34% 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.