Jewelweed is a wild Impatien. Touch-me-nots are tame Impatiens with similar sap with the same soothing quality on more managable plants. I get them at baker creek.

I've yet to meet any plant as good as a mudpack for poison oak or ivy after contact and in its early stages. Soothing emollients are nice for itchiness after a few days, but dessication is more important for shortening the course & severity of the skin outbreak, imo.

I'm not saying there aren't botanical remedies, just that a good clay is better than all of them and that it's almost always wrong to counteract urushiol with any oil-based solution -- if you can't wash it off quickly, then you want to chemically isolate the ivy's urushiol and keep that toxin's free alkyl groups from bonding with your skin, causing dermatitis. Oils won't do that, but soap, water, clays and certain organic molecules will.

Poison Ivy Wash is the best thing I have used for poison oak,poison Ivy or poison sumac.
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Safe for pregnant or nursing woman.
This is on the package.