GlaxoSmithKline plc (GSK) is a global pharmaceutical, biologics, vaccines and consumer healthcare company headquartered in London, United Kingdom. It is the world's third largest pharmaceutical company measured by revenues (after Johnson & Johnson and Pfizer). It has a portfolio of products for major disease areas including asthma, cancer, virus control, infections, mental health, diabetes and digestive conditions. It also has a large consumer healthcare division which produces and markets oral healthcare products, nutritional drinks and over-the-counter medicines, including Sensodyne, Horlicks and Gaviscon.
Its primary listing is on the London Stock Exchange and it is a constituent of the FTSE 100 Index. It has a secondary listing on the New York Stock Exchange.