Doxycycline is a broad-spectrum tetracycline class antibiotic used in the treatment of infections caused by bacteria and certain parasites. It is used to treat bacterial pneumonia, acne, chlamydia infections, Lyme disease, cholera, typhus, and syphilis. It is also used to prevent malaria in combination with quinine. Doxycycline may be taken by mouth or by injection into a vein.Common side effects include diarrhea, nausea, vomiting, abdominal pain, and an increased risk of sunburn. Use during pregnancy is not recommended. Like other agents of the tetracycline class, it either slows or kills bacteria by inhibiting protein production. It kills malaria by targeting a plastid organelle, the apicoplast.Doxycycline was patented in 1957 and came into commercial use in 1967. It is on the World Health Organizations List of Essential Medicines. Doxycycline is available as a generic medicine. In 2019, it was the 90th most commonly prescribed medication in the United States, with more than 8 million prescriptions. Medical use
In addition to the general indications for all members of the tetracycline antibiotics group, doxycycline is frequently used to treat Lyme disease, chronic prostatitis, sinusitis, pelvic inflammatory disease, acne, rosacea, and rickettsial infections.In Canada, in 2004, doxycycline was considered a first-line treatment for chlamydia and non-gonococcal urethritis and with cefixime for uncomplicated gonorrhea. Antibacterial
Moraxella catarrhalis, Brucella melitensis, Chlamydia pneumoniae, and Mycoplasma pneumoniae are generally susceptible to doxycycline, while some Haemophilus spp., Mycoplasma hominis, and Pseudomonas aeruginosa have developed resistance to varying degrees.It is used in the treatment and prophylaxis of anthrax and Leptospirosis.
Spectrum of susceptibility
Doxycycline has been used successfully to treat sexually transmitted, respiratory, and ophthalmic infections. Representative pathogenic genera include Chlamydia, Streptococcus, Ureaplasma, Mycoplasma, and others. The following represents MIC susceptibility data for a few medically significant microorganisms. Chlamydia psittaci: 0.03 μg/mL
Mycoplasma pneumoniae: 0.016 μg/mL—2 μg/mL
Streptococcus pneumoniae: 0.06 μg/mL—32 μg/mL

Sclerotherapy
Doxycycline is also used for sclerotherapy in slow-flow vascular malformations, namely venous and lymphatic malformations, as well as post-operative lymphoceles. Others
Subantimicrobial-dose doxycycline (SDD) is widely used as an adjunctive treatment to scaling and root planing for periodontitis. Significant differences were observed for all investigated clinical parameters of periodontitis in favor of the scaling and root planing + SDD group where SDD dosage regimens is 20 mg twice daily for three months in a meta-analysis published in 2011. Contraindications
Pregnancy and lactation
Doxycycline is categorized by the FDA as a class D drug in pregnancy. Doxycycline crosses into breastmilk. Other tetracycline antibiotics are contraindicated in pregnancy and up to eight years of age, due to the potential for disrupting bone and tooth development. They include a class warning about staining of teeth and decreased development of dental enamel in children exposed to tetracyclines in utero, during breastfeeding or during young childhood. However, the FDA has acknowledged that the actual risk of dental staining of primary teeth is undetermined for doxycycline specifically.