How do you know if you are allergic to Benzoyl Peroxide?!

How do you know if you are allergic to Benzoyl Peroxide?

I got some meds from my derm...
Benzac wash 5%
Cleocin gel
differin gel
cephalexin

so I have acne and all, which everything is working but I didnt use the Benzac wash in 2 days bc it burn my skin. I lather and rinse it, yet my skin had chemical burns comparable to a sunburn and it did peel. I tried proactiv before which irritated my skin. Not so badly, and you keep proactiv on all day. However, could this be an allergic reaction? Or maybe just sensitive to the Benz... or just bad in combination with the other products. I got a dermy appt. Weds. She say just use purpose soap and the other meds until then. What test can she do to see if I am allergic too?

3 weeks ago
I may become pregnant so she gave me the cephalexin instead. I only used the Benzac wash 2 1/2 days before my face was burnt like that. I quit for 4 days and just used the purpose soap she told me to sub if the wash irritated my skin and now it is fine. The benzac wash sped up acne clearing, but it hurt.

That stuff used all together will cause your skin to be very sensitive - shame on your dermatologist for not explaining that to you!!

You may have an allergy to benzoyl peroxide, so you should probably get back in touch with your doc. To rule it out yourself, you could stop everything for a week, then just try the Benzac wash and see if you still have the burning.

How long are you going to be on the cephalexin? This one surprises me - normally doctors stick with minocycline or doxycycline because of the anti-inflammatory properties. I'd get that clarified, too.