No Longer Accepting Cases

The FDA has ordered a label update for Tecfidera, a multiple sclerosis (MS) drug, to add new information about a patient who died of a rare brain infection known as progressive multifocal leukoencephalopathy (PML).

What is Tecfidera?

Tecfidera (dimethyl fumarate) is a prescription medication that is used to treat relapsing forms of multiple sclerosis (MS). It was approved by the FDA in March 2013. The original label carried warnings about PML.

FDA Safety Warning

November 25, 2014 — The FDA has issued a Safety Communication to report that a patient with MS who was taking Tecfidera developed a rare and serious brain infection known as PML, and later died.

The case was reported by Biogen, Inc., the manufacturer of Tecfidera. The patient had been taking Tecfidera for four years, but she was not taking any other drugs that affect the immune system.

She had low lymphocytes (white blood cells) in her bloodstream, which is a risk-factor for PML. This is the only confirmed case of PML in a patient on Tecfidera.

Similar drugs for MS, such as Gilenya and Tysabri, have been linked to hundreds of cases of PML.

FDA recommendation:

“Patients taking Tecfidera should contact their health care professionals right away if they experience symptoms that concern them, such as new or worsening weakness; trouble using their arms or legs; or changes to thinking, eyesight, strength or balance.”

What is PML?

Progressive multifocal leukoencephalopathy (PML) is a rare but serious infection of the brain. It is caused by the John Cunningham (JC) virus, which is a common virus that is normally harmless. The JC virus is more likely to activate and cause infections in people with weakened immune systems.


  • Progressive weakness on one side of the body
  • Clumsiness
  • Vision problems
  • Confusion
  • Changes in thinking, personality, memory, or orientation
  • Disability
  • Death