Allergan plc is an American, Ireland-domiciled multinational pharmaceutical company with its headquarters in Dublin, Ireland. The company was called Allergan Pharmaceuticals Inc. at the time of its inception and was famous for its eye-drops and anti-allergy drug. After its split with SmithKline Beckman in 1989, it acquired the Botox manufacturing company. However, Allergan plc emerged as a giant due to the fusion of its predecessor companies, Actavis plc and Allergan, Inc. While Actavis plc was founded by Allen Chao and David Hsia in the year 1983 as Watson Pharmaceuticals, Allergan, Inc. was founded in 1948 by Gavin S. Herbert under the name Allergan Pharmaceuticals Inc. The former began as a generic drug making company and the latter specialized in ophthalmic and anti-wrinkle products with Botox being its best-selling formulation. The first drug produced by the company was named Allergan by its founder Gavin S. Herbert and Stanely Bly. It was an antihistamine.The US- based company Allergan, Inc. was acquired by the Ireland-based Actavis plc in the year 2015 and Actavis plc took the name of Allergan. The US-based company Pfizer, in a bid to escape the high rates of the US corporate tax, had made an attempt to merge with Allergan. However the deal could not be executed after tax inversions were banned as a part of the new rules made by the government. In the year 2019, Allergan was acquired by AbbVie, a drug company based in Chicago and headquartered in the United States.

The company specializes in the therapy areas of ophthalmology, gastrointestinal disorders, women’s health, anti-infective, medical aesthetics, immunology and the central nervous system disorders.

The company has four manufacturing plants located in Ireland including the one at Westport. It has also set up a unit at Waco in Texas. The company also has a number of research facilities in various parts of the world. Allergan has an international presence in countries like Australia, China, Japan, France, Germany, Mexico, Spain, Netherlands, Turkey, UK, USA, Canada, Argentina, Brazil, Austria, Switzerland and Chile.

Some of the top products of the company are REFRESH TEARS, COMBIGAN, REFRESH LIQUIGEL, LUMIGAN, OPTIVE, ALPHAGAN-Z, BOTOX, FML LIQUIFILM, GANFORT, PRED FORTE, AMPLINAK, TEARS PLUS, NOVORET, FLUR, ALPHAGAN-P, FML-T, OSMEGA, ZYLOPRED, L-PRED, GLUCOMOL, ZYMAR, ACUPAT, ACULAR LS, RESTASIS, ZYMAXID, KETOMAR, MYTICOM, BRINZAGAN, ALPHAGAN, OPSION HA, EXOCIN, JUVEDERM-VOLUMA, GENTICYN, KETOFLOX, BETAGAN, EYEBREX, FML-NEO, JUVEDERM, OPTIVE FUSION, ACUVAIL, ALBALON, JUVEDERM-VOLBELLA, CELLUVISC, REFRESH EZEE, RELIF, RELESTAT, PREDNISOLONE ACET., ALBUCID, GENTICYN-HC and GENTICYN-B.