My face had been pretty bad lately so I had migrated to using 2.5% and 10% benzoyl peroxide. I use proactive steps 1-3. For those that don't know, step 3 is a 2.5% BP solution with some other things thrown in. I'll usually use step 3 and then apply my 10% BP. I've still been breaking out way more than usual lately. I switched to 10% BP after I had tried a new (terrible) face wash in an attempt to clear up again. My acne has been worse than usual this summer so I hoped the new wash would help. Instead it made my face purge itself terribly and I'm scared from it right now. I switched back to Proactive about 3 or so weeks ago (I used the other stuff for 2 weeks) and ever since my acne has been even worse than it was before I switched my wash. When I went back, I started incorporating the 10%. My face is not dry and I use a good moisturizer so dryness isn't a problem. I was wondering if maybe the 10% is just irritating my face and causing me to break out? Or if I should just give it some more time for my skin to adjust? (I would say I've only been really using 10% on my face for about a week so I could see why more time may be needed). Is my skin tightening its pours in a response to the 10% and in effect is pushing out some pimples?
Thanks!
Here's some info on bp strengths: http://www.acne.org/faq.html#higherpercentagebp
And here are Dan's thoughts on why Proactiv doesn't always work well. http://www.acne.org/faq.html#proactiv
I'm totally on board with Dan's thoughts on BP. I notice that my breakouts are worse when I'm running out of Proactive step 3 aka trying to conserve that expensive little bottle. When I have a new bottle and I'm using a good size blob, my breakouts are better. Glad to know its not just me!
BP will not cause breakouts, it provides the pore oxygen which kills the Bacteria. Maybe your face is coming back with extra oil production? My face is worse then ever and my regime is more extreme then ever, why won't my acne go away??? I blame it on being female!
I haven't noticed a difference between 5 and 10% BP. It's hard to find 5 but that is my preference as it is easier on the skin.
I stopped using the 10% and my acne has calmed down. I would recommend it ONLY as a spot treatment. It definitely increases irritation, and as we've all learned from the regimen, more irritation=more acne 
. Generally, what I have noticed, as Ahowe07 mentioned, the more extreme your regimen gets, the more extreme your acne gets! There's a nice middle ground . I think the best thing you can do for your face topically is stick to Dan's Regimen/your current BP regimen with 2.5% benzoyl peroxide, take a multivitamin with vitamins A, B5, biotin, and 4000-6000 IU's of vitamin D3. The best way to insure absorption is to make sure the vitamins you get are the food derived versions (they cost more but they're effective darn it!). Make sure you wash your face every 10-12 hours. No more as it will leave time for infection and no less because that would be added irritation.
One quick question though: switching from the Proactive Step 3 to Dan's BP wouldn't cause a reaction due to the difference in formulation between the two, would it? I'm really done with paying an exorbitant amount for Proactive's step 3 if I can be okay with Dan's BP