Poison Ivy Rash After 3 Weeks. Cortisone type preparations taken by mouth are dramatically effective in treating Poison ivy dermatitis rash. I can't believe that I'm still "getting" new areas of rash!
Also apply calamine lotion as it has a soothing effect on the skin. A common cold'll fool ya And whooping cough can cool ya But poison ivy, Lord'll make you itch! A poison ivy rash will only develop on skin that comes into contact with the plant's oils.
Frequently, the rash takes a linear form (as in the top-left corner of the photo) due to the way the plant sweeps across the skin.
All these years later, many myths about poison ivy persist.
But seemed to still spread days after. You may take oral antihistaminics like benadryl or zyrtec. A poison ivy rash will only develop on skin that comes into contact with the plant's oils.