Sorbitan sesquioleate: a rare contact allergen that is also an important indicator of allergic contact dermatitis from crossreacting compounds as well as for false-positive fragrance allergy.

SSO was a very good indicator for positive patch test reaction with unknown clinical relevance to fragrances and other allergens containing 1-5% SSO. We suggest that SSO should be tested as a negative control with any commercially available patch test allergen containing SSO at any concentration. Moreover, clinicians should be alert for SSO synonyms and for other sorbitan derivatives in product labels, as SSO itself might not be the culprit but an indicator for crossreacting allergens.