What is the best method to test for a true BPO allergy?

The best method to test for a true benzoyl peroxide (BPO) allergy is through conducting a patch test on the inner arm for three nights. This method involves applying a small amount of BPO to the skin, which allows a practitioner to observe any potential allergic reactions or irritation that may develop. Patch testing is a reliable way to determine if the client has a sensitivity or allergy to BPO, as it directly assesses the skin's response to the substance in a controlled manner.

Asking the client about past experiences with BPO may provide some insights, but it does not definitively verify whether they have an allergy. Personal reports can vary widely and may not reflect their current sensitivity. Convincing clients that they won't have a problem does not serve any diagnostic purpose; it could lead to unnecessary exposure and potentially harmful reactions if they do have an allergy. Thus, while gathering client history can be beneficial for understanding past reactions, it does not replace the need for an objective testing method like the patch test.