Levothyroxine is the generic form of the brand-name medication Synthroid. It is used to treat low levels of thyroid hormones, also known as hypothyroidism.

Founded in 1901, Teva Pharmaceuticals is the world's largest generic manufacturer with a total of 550 drugs. Its largest markets are in the UK, Germany, and the U.S but is in a top three leadership position in over 25 markets. Teva has 70 manufacturing sites including the U.S. and Israel.