Dimethyl fumarate (DMF) is the methyl ester of fumaric acid. DMF was initially recognized as a very effective hypoxic cell radiosensitizer. Later, DMF combined with three other fumaric acid esters (FAE) was licensed in Germany as oral therapy for psoriasis (trade name Fumaderm). Phase III clinical trials found that DMF (BG-12) successfully reduced relapse rate and increased time to progression of disability in multiple sclerosis (trade name Tecfidera). DMF is thought to have immunomodulatory properties without significant immunosuppression. The mechanism of action of dimethyl fumarate in multiple sclerosis is not well understood. It is thought to involve dimethyl fumarate degradation to its active metabolite monomethyl fumarate (MMF) then MMF up-regulates the Nuclear factor (erythroid-derived 2)-like 2 (Nrf2) pathway that is activated in response to oxidative stress. Dimethyl fumarate is marketed under the brand name Tecfidera.