Concomitant contact-allergic reactions to iodopropynyl butylcarbamate and iodine

Iodopropynyl butylcarbamate (IPBC) is a broad-spectrum preservative for use in several product types, including cosmetics, in which its concentrations have been limited by EU legislation because of concerns related to its iodine content and release, and the risk of subsequent iodine overdose.

To report on concomitant patch test reactions observed with iodine and IPBC in patients sensitized to iodine-containing antiseptics.

Between 2012 and 2018, seven patients, six from Belgium and one from France, two suffering from acute dermatitis during surgical interventions, four from dermatitis caused by wound treatment, and one from occupational dermatitis, were shown to be sensitized to iodine and/or povidone-iodine (PVP-I), which was considered to be relevant for their dermatitis. All patients were coincidentally also patch tested with IPBC.

All patients showed positive patch test reactions to several other allergens, including IPBC. No relevance could be detected for IPBC.

We suspect that, notwithstanding the absence of firm evidence for IPBC being dehalogenated to produce free iodine in animals or in humans, the patch test reactions to IPBC in iodine-allergic subjects were possibly caused by free iodine released from this preservative agent, thus underlining the EU restrictions regarding the use of this preservative in cosmetics.