Tecfidera starts to work within 24 weeks; however, it may take up to two years for the full effects to be seen.

Studies report that after 2 years, people taking Tecfidera were:

• 44% to 53% less likely to relapse every year when taking Tecfidera compared with those taking placebo
• 21% to 28% less likely to have a progression of their disability while taking Tecfidera compared to those assigned to placebo
• 74% to 90% less likely to develop new or newly enlarging T2 lesions or have Gd lesions.

It took 24 weeks for a difference to be noted between Tecfidera 240mg twice daily and placebo for the time to 12 week confirmed progression of disability; 6% of people taking Tecfidera had a confirmed progression of disability vs 8% taking placebo after 24 weeks. After 2 years 16.4% taking Tecfidera had disability progression compared with 27.1% assigned to placebo which corresponded to a risk reduction of 38%. Another study reported a 21% risk reduction in disability progression.

Disability progression was defined as at least a 1 point increase on the EDSS (Expanded Disability Status Scale) from the baseline EDSS of >1, or a 1.5 increase on the EDSS from a baseline EDSS of 0 which was confirmed for at least 12 weeks.