Doxicon has been found clinically effective in the treatment of a variety of infections caused by susceptible strains of Gram-positive and Gram-negative bacteria. Doxicon Mg Capsule. Description: Each capsule contains: Doxycycline (as Hydrochloride) mg. Indications / Uses: For the treatment of respiratory. Doxicon(Doxycycline): Chlamydial non-gonococcal urethritis, uncomplicated urethral & endocervical infections, acne vulgaris; resp tract, ENT, GUT, &.