Doxycycline is a broad-spectrum tetracycline antibiotic commonly prescribed to treat various infections including sexually transmitted infections such as Chlamydia. How effective is Doxycycline in treating Chlamydia? Doxycycline is a highly effective antibiotic for the treatment of Chlamydia. 95% of all cases of chlamydia are able to be treated with this antibiotic. This alongside Azithromycin are first line treatments for chlamydia. Azithromycin vs Doxycycline as Chlamydia Treatment Both medications are still used for treating uncomplicated chlamydia infection. Both these antibiotics work differently to attain the same outcome. Doxycycline is one of the  recommended first line treatments for this infection, whilst Azithromycin is a useful alternative for those individuals who cannot tolerate Doxycycline or other Tetracycline antibiotics.