Understanding safety and potential side effects

It's important to talk to your healthcare provider if you've had an allergic reaction to Tecfidera® (dimethyl fumarate) or any of its ingredients. You should also discuss the serious side effects associated with TECFIDERA, including:

Allergic reactions

Allergic reactions (such as welts, hives, swelling of the face,
lips, mouth or tongue, or difficulty breathing).


PML, which is a rare brain infection that usually leads to
death or severe disability.

Decreases in your
white blood cell count

Your healthcare provider should check your white blood cell count before you take TECFIDERA, 6 months after starting treatment, and then every 6-12 months after and as they feel necessary.

Liver problems

Your healthcare provider should do blood tests to check your liver function before you start taking TECFIDERA and during treatment if needed. Tell your healthcare provider right away if you get any symptoms of a liver problem during treatment, including:

  • severe tiredness
  • loss of appetite
  • pain on the right side of your stomach
  • dark or brown (tea color) urine
  • yellowing of your skin or the white part of your eyes

Your healthcare provider should do a blood test before you start treatment with TECFIDERA and while you’re on therapy.

TECFIDERA Pregnancy Registry

You should always talk to your healthcare provider before taking TECFIDERA if you're pregnant, interested in becoming pregnant, breastfeeding or planning to breastfeed. That's because it isn't known how taking TECFIDERA would affect an unborn baby or if it passes into your breast milk. If you're pregnant while taking TECFIDERA, talk to your healthcare provider about enrolling in the TECFIDERA Pregnancy Registry to monitor your health and the health of your baby.

TECFIDERA Pregnancy Registry

Learn about common side effects of TECFIDERA and get tips to help manage them.