Extensor hallucis Longus Tendonitis and Marathon

Searching this forum and the internet I found my diagnosis. R foot EHL tendonitis. I have pain and swelling on anterior part of the right foot halfway between big toe and ankle, not a fracture. Goes away if I don’t run for a few days. Returned yesterday after a 15km run at the 10k split. I tried Advil and icing and it helps but cutting down the running really helped last week after a 75km week which really flared it up. My problem is that my marathon is in 4 weeks. Is it reasonable to try and train or give up on the marathon ?
Should I try cortisone creme locally ?

Thanks

Cortisone cream won’t do anything, unless you slather it all over your body AND cover yourself with Saran Wrap, then you MIGHT, PERHAPS, MAYBE absorb enough to relieve inflammation somewhere in your body. It only works for skin problems.

almost always caused from shoes being too tight. Can also be caused by a dorsal exostosis (bone spur) off the great toe joint. Unusual “overuse” tendonitis injury in a pure runner (even during a marathon build). More common here in ballet and dancing.

Topical steroid cream probably won’t do much, but won’t hurt I suppose. Ice after running, loosen your laces, DON’T massage/stretch the area to let it calm down (usually responds quickly to rest - not something you are likely to do unfortunately). A corticosteroid injection to the tendon sheath can work wonders if it won’t respond or you ‘must’ race.