Hydrocodone or dihydrocodeinone is a synthetic opioid derived from either of two naturally occurring opiates: codeine and thebaine. It is an orally active narcotic analgesic (pain reliever) and antitussive (cough suppressant). It is available in tablet, capsule, and syrup form, and is often compounded with other, generally less effective non-opioid compounds such as paracetamol (also known as acetaminophen) or ibuprofen, both often added to discourage recreational use^{[citation needed]} (as paracetamol can cause potentially fatal liver toxicity at high doses), and to provide a possible synergy of analgesic effects between hydrocodone and the non-opioid compounds present. The particular niche in which hydrocodone is most commonly used is as an intermediate centrally acting analgesic. Abrupt discontinuation of hydrocodone (Vicodin, Vicodin ES, and Norco) may result in withdrawal symptoms.