I am using duac once daily gel and taking erythromycin 250 mg twice daily, I am wondering why you cannot mix these medications, as my doctor prescribed them to me along with differin cream. I am alternating nights for the creams and using them every second night. I am wondering do i need to come off erythromycin? I was taking minox before but my doctor put me on erythromycin as the minox was not helping much. I would be grateful of your advice!