I would give the Minocin at least another couple of weeks before you give up on it. Also, when you say 100mg, I take it you mean that is your total daily dose. Its quite possible that you may need to take 100mg twice a day for it to be effective, particularly if your acne is severe or cystic. You may also want to discuss with your Doctor about using a prescription topical medication such as BenzaClin or Differin while on the oral antibiotics.
Please do a little research online in regard to the possible side effects of taking Minocyline. My 18 year old daughter took Minocycline for acne for 3 months, became very, very sick and was diagnosed with drug-induced autoimmune hepatitis as a result of the Minocycline. This is a very serious illness, and, in hindsight, was not worth the cost.
I'd suggest the following:
(For my own acne)
I use the BezaClin, It's great, does dry out your skin a bit, but if used lightly it will give you the effects your going for.
Do not try Proactive- Been there, done that-Seen all the info- commercials till i almost ran in debt- Just kidding (Those things work for some people, and others they don't)
I also take an antibiotics, Forget the name of it. But it is a sulfar base, twice daily, in the morning and one at night. I haven't had any bad side affects to date.
Try buying an alcohol base anti-oil thingy. Heck, it's so late here. I can't remember, Agh, yes Antiaginic i think. I will have to use the google. (ONE SECOND)
agh well, I messed up, all i've found says alcohol is bad for the skin.
But the Benzaclin is a charm