Doxycycline is a semi-synthetic tetracycline, which belongs to the tetracycline class of drugs. Doxycycline also belongs to an antibacterial drug, a broad-spectrum antibacterial agent, mainly interfering with the protein synthesis of sensitive bacteria, can target high concentrations of various mycoplasma, chlamydia and mycobacterial infections, through doxycycline and get good inhibition. Doxycycline drug side effects are more, common side effects are gastrointestinal discomfort reactions, nausea, vomiting, etc. It is best not to drink on an empty stomach, after half an hour after the meal application will be less harmful to the gastrointestinal tract. Doxycycline is effective for Gram-positive cocci and negative bacilli, many Rickettsia spp, Mycoplasma spp, Chlamydia spp, Atypical Mycobacteria spp, Spirochetes are also sensitive to this product, others such as Actinomyces spp, Bacillus anthracis, Listeria monocytogenes, Clostridium difficile are also sensitive to this product, but Enterococcus spp are resistant to it.