How long does it take for benzaclin (clindamycin and benzoyl peroxide) to really work?

At least 8 weeks: When using any topical medication for acne, it takes at least 8 weeks to see the optimal efficacy of the medication. In my opinion, it is best to use several treatments for acne instead of one as there are multiple causes to acne. Your benzoyl peroxide/ Clindamycin is a good choice for the bigger bumps, but you may need a retinoid to help with clogged pores and oil.