Azithromycin is an antibiotic medication used for the treatment of a number of bacterial infections. This includes middle ear infections, strep throat, pneumonia, travelers diarrhea, and certain other intestinal infections. Along with other medications, it may also be used for malaria. It can be taken by mouth or intravenously with doses once per day.Common side effects include nausea, vomiting, diarrhea and upset stomach. An allergic reaction, such as anaphylaxis, QT prolongation, or a type of diarrhea caused by Clostridium difficile is possible. No harm has been found with its use during pregnancy. Its safety during breastfeeding is not confirmed, but it is likely safe. Azithromycin is an azalide, a type of macrolide antibiotic. It works by decreasing the production of protein, thereby stopping bacterial growth.Azithromycin was discovered in 1980 by the Croatian pharmaceutical company Pliva and approved for medical use under the brand name Sumamed in 1988. It is on the World Health Organizations List of Essential Medicines. The World Health Organization classifies it as critically important for human medicine. It is available as a generic medication and is sold under many trade names worldwide. In 2019, it was the 48th most commonly prescribed medication in the United States, with more than 15 million prescriptions. Medical uses
Azithromycin is used to treat diverse infections, including:

Prevention and treatment of acute bacterial exacerbations of chronic obstructive pulmonary disease due to H. influenzae, M. catarrhalis, or S. pneumoniae. The benefits of long-term prophylaxis must be weighed on a patient-by-patient basis against the risk of cardiovascular and other adverse effects.
The concentration of azithromycin in the tissues can be over 50 times higher than in plasma due to ion trapping and its high lipid solubility. Azithromycins half-life allows a large single dose to be administered and yet maintain bacteriostatic levels in the infected tissue for several days.Following a single dose of 500 mg, the apparent terminal elimination half-life of azithromycin is 68 hours. Biliary excretion of azithromycin, predominantly unchanged, is a major route of elimination. Over the course of a week, about 6% of the administered dose appears as an unchanged drug in urine. History
A team of researchers at the pharmaceutical company Pliva in Zagreb, Croatia,—Gabrijela Kobrehel, Gorjana Radobolja-Lazarevski, and Zrinka Tamburašev, led by Slobodan Đokić—discovered azithromycin in 1980. The company Pliva patented it in 1981. In 1986, Pliva and Pfizer signed a licensing agreement, which gave Pfizer exclusive rights for the sale of azithromycin in Western Europe and the United States. Pliva put its azithromycin on the market in Central and Eastern Europe under the brand name Sumamed in 1988. Pfizer launched azithromycin under Plivas license in other markets under the brand name Zithromax in 1991. Patent protection ended in 2005. Society and culture
Available forms
Azithromycin is available as a generic medication. Azithromycin is commonly administered in film-coated tablet, capsule, oral suspension, intravenous injection, granules for suspension in sachet, and ophthalmic solution. Usage
In 2010, azithromycin was the most prescribed antibiotic for outpatients in the US, whereas in Sweden, where outpatient antibiotic use is a third as prevalent, macrolides are only on 3% of prescriptions.