It takes a few days until the redness in my face disappears.
My face stays red for a few days sometimes.
この場合、次のように言うと良いでしょう。
ーIt takes a few days until the redness in my face disappears.
「顔の赤みが消えるまでに数日かかる」
ーMy face stays red for a few days sometimes.
「時々顔が数日赤いままだ」
例：
I'm allergic to peanuts and they make my face really red. It takes a few days for the redness in my face to disappear.
「ピーナッツアレルギーで顔がすごく赤くなり、顔から赤みが消えるのに数日かかる」
ご参考まで！
カナダ 
