How long would poison ivy last if you start taking steroids?

Poison ivy rashes: Those are contact dermatitis rashes due to contact with the oil (urushiol) found in all parts of the plant. The more oil you come to contact with the more symptoms you get ranging from simple skin redness to blistering lesions. If untreated, it lasts anywhere from 10 days to 3 weeks. It would last longer if your skin is more severe e.g. Blister forming. Oral or topical steroid hasten the healing.