If i used benzoil peroxide in the past, did i already built tolerance to BP or i lost it?

well it all depends on your skin, but I was in the same shoes as you where I was using products with high % of benzoyl peroxide for a very long time and I could tolerate it. But, I stop using it for about a month or so, then used it again, and got an allergic reaction. So, I started to use products with Salicylic Acid and it works fine and BETTER.