Sorry to hear that you are having this problem. From the language of your question (“I may have an allergy”) it appears that you don’t have a definitive diagnosis yet. Until you are relatively certain about what you are reacting to, making smart decisions about which cosmetics and products to use and which to avoid can be hit-and-miss. In principle, I agree that you should take steps to reach a specific diagnosis about what is causing the problem before you start making decisions about which products to use and which ones to avoid using. The difficulty with doing this on your own is that the diagnosis of a specific chemical sensitivity can be perplexing even for a medical professional who has years of experience. The DIY route is likely to be confusing and may not help you solve the problem. This is especially the case with a potential benzalkonium chloride allergy since not only is allergy to this class of chemicals relatively common (about 2 – 7 percent of the population) but this group of compounds increase the likelihood of allergies to many other chemicals and antigens. For this reason, sensitivity testing always includes pure compounds, associated compounds, and controls. Even then, interpretation of a pattern of response can be challenging. My suggestion to you is that you follow–up with a dermatologist who is a member of the American Contact Dermatitis Society and has years of experience solving these problems. Working through the problem with the right medical professional until you have an accurate diagnosis, a working understanding of what is causing the problem, and a treatment plan to avoid recurrence is your best bet.

I just got back from an allergy doctor at Mayo who told me that I may have an allergy to benzalkonium chloride. I have had a rash on two specific places on my lips for six months and have struggled with eye allergies for over a year. The only thing that worked for me was to completely stop using any and all products, including soap, lotions, cosmetics, sunscreens, contacts, drops, etc. Is there any way to tell for sure that it is benzalkonium chloride? I’d like to eventually be able to use some of these products again, but don’t want to risk a reaction again. Is it safe to do an “at home” patch test on my arm, for example? Is there some product out there that has a high concentration at a fairly cheap price?

Thank you for your community outreach and important research.