grandma's poison ivy bar 2oz. (6) remwood jewelweed stops the itching of poison ivy, oak, and sumac almost immediately and clears up the rash in 2 to 3 days. for centuries, jewelweed, a rare plant, has been used as a natural preventative and treatment for poison ivy, oak, and sumac. contains natural impatiens capensis, an excellent substitute for corticorsteriods. 2 oz. bar.