Hello Jayney8
I had really bad skin until I was 30, and  it really used to get me down. 
I have taken both oxytetracycline and erythromycin orally in the past.  Both quite effective. 
From memory the oxytetracycline was fine, I don't recall any ill effects but you have to take it on an empty tummy to get full effect which was a bit of a pain! 
RR xx