Androgens (male hormones found in male and female bodies) stimulate the sebaceous glands in
the skin. Bacteria on the skin feed off this excess
oil, called sebum, blocking the pores and leading to inflammed spots.
If oxytetracycline and doxycycline didn't work other antibiotics may help; lymecycline, erythromycin or minocycline. Alternatively, topical antibiotics (clindamycin, erythromycin) or topical retinoids (tretinoin, adapalene) may work.