Skin rash to antiseptic

A question about skin testing to povidone iodine was raised in a prior Ask The Expert inquiry. I have copied and pasted Dr. Ledford's response below as it may be of use to you if your sense was that the rash was characteristic of an IgE-mediated reaction.

Regarding patch testing with Duraprep, I could not find any literature nor could I find any reports of cross-reactivity between Duraprep and Betadine. I could not find reports of Duraprep allergy but I found numerous reports of isopropyl alcohol allergic contact dermatitis and isopropyl alcohol is a component of Duraprep. A 2011 publication tested 1450 patients to isopropyl alcohol using it "as is, pharmaceutical grade" and diagnosed 44 patients with allergic contact dermatitis to this agent.

It is important to note that patch testing may be done with particular implicated products that are not part of existing standardized kits, but dilutions may be required in order to distinguish irritant from allergic responses. I am sorry that I could not be of more help.

Reference:
Garcia-Gavin J, Lissens R, Timmermans A and Goossens A. Allergic contact dermatitis caused by isopropyl alcohol: a missed allergen? Contact Dermatitis 2011 Aug; 65(2):101-6.

Here is Dr Ledford's response:
Povidone iodine allergy is very rare but has been reported. Skin testing with undiluted (25mg/ml) solution has been reported but the predictive value of positive and negative testing is not defined (Gray). Other topical antiseptics, notably chlorhexidine, have also been associated with systemic reactions, particularly when applied to disrupted or injured epithelial surfaces. One report suggests that over 9% of perianesthetic anaphylaxis may be related to chlorhexidine sensitivity (Opstrup).

Iodine as an antigen or component of radiocontrast dyes is not related to radiocontrast reactions. Therefore, there is no relationship between radiocontrast sensitivity and povidone iodine.

In summary, povidone iodine is a rare cause of allergic or allergic-like reactions. Prick skin testing has been reported using a concentration of 25mg/ml (undiluted) [Gray]. Chlorhexidine may also cause systemic reactions, but there is no cross-reactivity between chlorhexidine and povidone iodine. Radio contrast reactions are not related to iodine allergy. There is no concern about possible cross-reactivity between radiocontrast and povidone iodine.

Recurrent anaphylaxis caused by topical povidone-iodine (Betadine). Gray PE, Katelaris CH, Lipson D. J Paediatr Child Health. 2013 Jun;49(6):506-7

Standardized testing with chlorhexidine in perioperative allergy--a large single-centre evaluation. Opstrup MS, Malling HJ, Krøigaard M, Mosbech H, Skov PS, Poulsen LK, Garvey LH Allergy. 2014;69(10):1390.

I hope this information is of help to you and your patient.

Dennis K. Ledford, MD, FAAAAI

Jacqueline A. Pongracic, MD, FAAAAI