Doxycycline is related to
minocyclineMinocycline
Minocycline hydrochloride
Minocycline hydrochloride er, but is a different drug, so it's worth trying. Your doctor is right about the expected time frame for improvement. If
doxycyclineDoxycycline
Doxycycline hyclate
Doxycycline monohydrate doesn't clear things up in 3-4 months, there are other, non-cycline antibiotics which could be tried, and beyond those, Accutane may be worth considering.
Despite what people say, sweating from working out does not aggravate acne. At most, it makes pimples redder, but that's just a visual effect, not a true worsening.
Take care.
Dr. Rockoff