Olive oil--contact sensitizer or irritant?

Adverse cutaneous reactions to topically applied olive oil are seldom reported, and positive patch tests to it are mostly regarded as allergic. To evaluate such "positive" patch test reactions, 77 female (mean age: 44 years) and 23 male eczema patients (mean age: 46 years) were prospectively patch tested with freshly prepared olive oil. Tests were performed openly (including ROAT) as well as using Al-tests and Finn Chambers on Scanpor. 5 patients (2 male) showed "positive" test reactions (all patients at the Al-test site, 3 at the Finn Chamber site, 1 with ROAT). In only 1 patient could the reaction be classified as probably allergic, in contrast to previous reports. In conclusion, olive oil is very weakly irritant in general, but bears relevant irritant capacity when applied under occlusive conditions. Therefore, olive oil appears to be less than suitable for the topical therapy of patients with venous insufficiency and associated eczema of the lower extremities.