Metamizole (INN), or dipyrone (BAN, USAN), is an ampyrone sulfonate analgesic (pain reliever), antispasmodic (spasm reliever) and antipyretic (fever reducer) similar to paracetamol in that it has minimal anti-inflammatory effects and which is most commonly given orally or parenterally (by injection) to prevent and treat pain related to surgery or for the treatment of acute pain. It was first introduced into clinical use in Germany in 1922 under the brandname "Novalgin" and for many years it was available over-the-counter in most countries, until its toxicities became apparent, although in some countries it is available over-the-counter, its use is usually restricted in developed countries, due to its potential for causing toxic reactions.