Benzoyl peroxide / clindamycin
"My GP had prescribed this to me at my requests for something to deal with my acne. I used this medication for about a month or a little longer. This medication dries out my face something terrible. I had to slather moisturizer on my face, which was probably counterintuitive. The medication worked well at drying out existing acne on my face but did nothing to prevent new acne. Every day I would wake up to new zits. I ended up going to a dermatologist and had something else prescribed. 



Also, with this medication containing benzoyl peroxide it stains your sheets very badly (thankfully, I already had a pillow case that resisted staining, same can't be said for the sheets)."