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

Research output: Contribution to journalArticle


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.


External organisations
  • Sahlgrenska University Hospital
  • Örebro University Hospital
  • Örebro University
  • Umeå University
  • University of Gothenburg
  • Sahlgrenska Academy
  • NU Hospital Group
  • Skåne University Hospital
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Dermatology and Venereal Diseases


  • allergic contact dermatitis, autoxidation, citral, fragrance mix I, fragrance mix II, geranial, geraniol, neral, oxidized geraniol, patch testing, RRID:SCR_001905
Original languageEnglish
Pages (from-to)31-38
JournalContact Dermatitis
Issue number1
Early online date2019 Sep 30
Publication statusPublished - 2020
Publication categoryResearch