ALee2010

I also think reactions can start as soon as you apply the product but if you started getting the bumps after a week and a half of using it, I'd say this is purging. But, I am not a Derm of Esthetician...

Any time you start a new product with actives you may get purging. I started purging when I started using the acne.org benzoyl peroxide. Is it itching or burning? If so it is probably a reaction. But ...

Hey! Yes it will still be effective....please, please, please START SLOW! I am speaking from experience. You will have to build up your tolerance again. If it worked for you before, it will work again...

The dryness is simply from the Benzoyl Peroxide. Make sure you are using enough moisturizer. Someone can correct me if I am wrong... but I think your face might look darker because of the rate of cell...