Doxycycline tablets are tetracycline antibiotics and may be used and dosed differently depending on the therapeutic use, ranging from 50 to 200mg. It should be used under medical supervision. Doxycycline tablets are tetracycline antibiotics with broad-spectrum antibacterial effect, which can be used for the treatment of rickettsial diseases such as epidemic typhus, chlamydial infections such as psittacosis, cervicitis, etc., and also as an adjunctive treatment for acne. 1. Doxycycline tablets should be used under medical supervision. For antibacterial and antiparasitic infections, 100mg (1 tablet) every 12 hours on the first day; a total of 100~200mg (1~2 tablets) per day on the subsequent days, which can be used up at once or every 12 hours, i.e., 50~100mg (0.5~1 tablets)/times, 2 times/day. 2. When doxycycline is used for the treatment of Neisseria gonorrhea urethritis and cervicitis, 100mg (1 tablet) is used twice a day for 7 days. For the treatment of simple urethritis, cervicitis, and rectal infections not caused by Neisseria gonorrhea but by Chlamydia trachomatis and Ureaplasma urealyticum, 100 mg (1 tablet)/times, twice a day, for a total of at least 7 days. Doxycycline should not be used in persons with a history of hypersensitivity to this drug. Adverse reactions such as nausea, vomiting, diarrhea, dry mouth, pharyngitis may occur during use, and the drug should be used under the guidance of a doctor, following the doctor’s instructions, taking the medication on time, and seeking medical attention in case of discomfort.