Tecfidera Uses, Dosage, How to Take, Side Effects and Warnings

Tecfidera warnings. Tecfidera may cause a viral infection in the brain called progressive multifocal leukoencephalopathy (PML), which could lead to serious injury or death. Call your doctor right away if you experience any of the following symptoms while taking this medicine:

  • decreased vision or vision problems
  • a change in mental state
  • weakness on one side of the body
  • trouble with speaking or walking