Contact allergy from propylene glycol

Propylene glycol (PG) 20% in water was tested in a group of 400 subjects with eczematous contact dermatitis. In six inpatients (1.5%) reactions were recorded as considered positive according to the following criteria: 1. the relevant history of prolonged contact with PG-containing topical pharmaceutical and cosmetic preparations; 2. the reaction extended in time outside the area of application of the test substance, and persisted locally for several day; 3. a similar reaction was obtained on repetition of the test with a lower concentration of PG; 4. the prompt improvement in clinical manifestations of eczema on withdrawal of PG-containing topical preparations. With the PG concentration employed no irritant reactions were observed.