"i used doxycycline and i really loved the results. the reason why i&#039;m writing here is that i see everyone&#039;s getting sore stomachs or discomfort, and i did get that too. i went to my beautician, and she said to take a prebiotic before you take doxycycline. i tried and it, and it really worked! my stomach pains where gone and my skin was clearing. no harm in trying, so go for it."