I get poison ivy every year. What works for me is to take a Reactine allergy pill, which controls hives as written on the label. Most allergy pills don't control hives. Calimine lotion will make you more sensitive to next time you get poison ivy. I recently read in a hunting magazine that PreperationH helps to tighten up the blisters and heal much faster. Haven't had the pleasure of trying the PreperationH yet. Note that the Reactine works good only once per season. If you get poison ivy a second time in a season you may have to triple dose.