This is one of my favorites. I see several patients every day with a drug allergy or contact allergy; last week I saw a pleasant gentleman with an intractable itchy rash on his hands, arms, and abdomen. He had been suffering for months and got relief only with oral prednisone. I was concerned that he might have a contact allergy and performed patch testing. I placed patches of 24 common allergens on his back which stayed for 48 hours before being removed and read the next day.
The patch test showed he was 3+ positive (that’s very positive) for carba mix, compounds used in the manufacturing or rubber. “That’s impossible,” he said. “Why?” I asked. “Because I’ve worked in a tire store my whole life,” he replied.
It is a pervasive misconception that if you have been using a product like a lotion, or been in contact with something like rubber, or even taken a medication like aspirin for a long time that you cannot be allergic to it. That’s false. You can become allergic to it.
In order to be allergic to something, like rubber, you must have been exposed to it or to something very similar to it. You cannot be allergic to something you have never been exposed to. My patient was exposed to rubber without problem for years, but then suddenly his immune system targeted it, leading to his allergy. Although it is most common to develop an allergy to something that you have been exposed to recently, the allergy can develop after prolonged exposure.
The immune system is fantastically complex. It manages to determine what is foreign and harmful to you with almost flawless accuracy, but sometimes it gets it wrong. The times when it responds inappropriately to harmless chemicals in your environment is what keeps me in business.
Photo credit: Eric Castro