Allergen of the Year: Neomycin

From Twitter:

@sandnsurf: Neomycin named allergen of the year http://bit.ly/d508Le via @mdconsult

@Paulflevy: never knew there was a competition for this (allergen of the year)! Is there a prize? :)

@rlbates: Not that I know of, but maybe we could come up with something like the Razzie awards. First thought -- the Rashie

@sandnsurf: brilliant, love it. The Rashie it is! We should have a Rashies ceremony at the end of 2010 and have @DrVes preside

@Paulflevy: Maybe the first prize is a year-long subscription to Benadryl!

Good thoughts! A few clarifications are in order. The American Contact Dermatitis Society started selecting "allergen of the year" more than 10 years ago to heighten the awareness that common everyday products can be the cause of contact dermatitis. This is a type IV, cell-mediated, delayed reaction, therefore antihistamines such as over-the-counter Benadryl will not help.

The American Contact Dermatitis Society has named the aminoglycoside antibiotic neomycin as Allergen of the Year for 2010.

From MDConsult:

Because neomycin is sold over the counter, physicians need to remember to ask patients with dermatitis about all products they use, not just prescription medicines. Many patients don’t think to tell you they are using an OTC antibiotic.

Heightened clinical suspicion also is warranted because of delayed reactions. Dermatitis from neomycin often develops 7 days or more after exposure. Most physicians who apply patch test take readings at 48 hours and 96 hours, but a reaction from neomycin may not even appear by 96 hours.

Informing and educating patients about the many vaccines that contain neomycin as a preservative is a third implication for physicians.

A neomycin reaction is not a type 1 IgE-mediated allergy - it’s a type IV reaction that produces eczema.

Also keep cross-reactivity in mind. Neomycin is a member of the aminoglycoside family, which also includes gentamicin, kanamycin, and tobramycin. “It always amazes me that I will see patients who know they are allergic to neomycin, and they will come in to see me because they have very severe ear dermatitis, and they are using tobramycin as an ear drop."

Gold was the 2001 Allergen of the Year, and reactions to gold are common and clinically problematic. Bacitracin (2003) and glucocorticosteroids (2005) are other allergens that are both common and clinically relevant. In contrast, thimerosal (2002) is a common but nonrelevant allergen because it was removed from most products in the United States.

References:
Neomycin named allergen of the year. MDConsult.
How to Diagnose Contact Dermatitis?

Post-Traumatic Basal Cell Carcinoma Associated With Patch Testing - with strongly positive reaction to gold. Actas Dermo-Sifiliográficas (English Edition), 2009.

Image source: Amazon.com, used for illustrative purposes only - NOT a suggestion to purchase any medications.