The main difference between doxycycline and minocycline is the composition, and the difference in antibacterial strength. 1. Different main components: the main component of doxycycline tablets is doxycycline, a semi-synthetic antibiotic obtained by deoxygenation of oxytetracycline at the 6α-position; the main component of minocycline tablets is minocycline, which is also a semi-synthetic tetracycline antibiotic. 2. Antibacterial strength and weakness: doxycycline and minocycline are tetracycline antibiotics, both drugs are long-lasting, highly effective antibacterial drugs, and antibacterial spectrum. In comparison, among tetracycline antibiotics, minocycline has high fat solubility and good permeability, so its antibacterial activity is the strongest. Both drugs have the common adverse reactions of tetracycline antibiotics, and must be used in strict accordance with medical advice.