I am already on acne antibiotic gels, I would like to know of a medicine to use on already started pimples, to reduce them (apart from preventing).

Add another Rx. Many men do not get adequate relief from an antibiotic gel. It may be time to talk with your physician about a systemic antibiotic, or if you're ready for a medication such as Accutane which is extremely effective but rather unpleasant and a bit risky, now's the time to make this known. This is the 21st century and we can clear you up if that's your wish.