Allergic contact dermatitis from propylene glycol: A case series from Australia

Propylene glycol (PG) is used in a variety of cosmetics, food and pharmaceuticals. PG is a known sensitizer but also irritating when patch tested (PT).

The aims were to investigate the frequency of contact sensitization to PG and to identify cases of allergic contact dermatitis (ACD).

A retrospective study was performed on patients PT at the Skin Health Institute (SHI), Victoria, Australia to PG 5% pet. and PG 10% aq. between 1 January 2005 and 31 December 2020.

In all, 6761 patients were PT to PG and 21 (0.31%) reacted. Of those 21 individuals, 9 (42.9%) had a relevant reaction. 75% of relevant positive reactions were in patients PT to PG 10% aq. The most common source of PG exposure was topical medicaments (77.8% of relevant reactions) and moisturizers, with the largest group being topical corticosteroids.

Contact sensitization to PG in the patch test population remains uncommon, although it is possible that testing with concentrations of 5%-10% PG did not identify all reactions. Topical corticosteroids were the most important cause. Patients with suspected contact dermatitis to topical corticosteroids should be PT to PG.