Diclofenac, sold under the trade names Voltaren among others, is a nonsteroidal anti-inflammatory drug (NSAID) used to treat pain and inflammatory diseases such as gout. It is taken by mouth or applied to the skin. Improvements in pain typically occur within half an hour and last for as much as eight hours. It is also available in combination with misoprostol in an effort to decrease stomach problems.Common side effects include abdominal pain, gastrointestinal bleeding, nausea, dizziness, headache, and swelling. Serious side effects may include heart disease, stroke, kidney problems, and stomach ulceration. Use is not recommended in the third trimester of pregnancy. It is likely safe during breastfeeding. It is believed to work by decreasing the production of prostaglandin. It blocks both cycloxygenase-1 (COX-1) and cycloxygenase-2 (COX-2).Diclofenac was patented in 1965 by Ciba-Geigy and came into medical use in the United States in 1988. It is available as a generic medication. In the United States the wholesale cost per dose is less than US$0.15 as of 2018. In 2016 it was the 78th most prescribed medication in the United States with more than 9 million prescriptions. It is available as both a sodium and a potassium salt.