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.

Diclofenac is used to treat pain, inflammatory disorders, and dysmenorrhea.