Does Doxycyline have any affect on muscle and height growth? I have been on Doxycyline for 2 months before, but now my acne is back, and Doxycyline doesn t seem to work anymore. I re searched, and maybe changing other medicine may help, and if I don t want to be on any medicine. It says some medical laser treatments can help? Is that right? And if not, what can I do to help with my acne and what better medicine do you recommend me to take if there aren t any better treatments? Furthermore, does testosterone help with height or muscle growing at all? What is best taken for height growing, any medicine at all? And does it do anything to you penis sizes?