Made from Rhus toxicodendron (poison ivy), this homeopathic remedy has been in use for 80 years. Also called Rhus tox, it's taken before or after exposure. A recent study found that Rhus tox reduced the severity of symptoms related to toxic-plant exposure. As a preventive, dissolve two pills on your tongue morning and evening for one week. Repeat in 30 days. If you've been exposed, dissolve two tablets on your tongue every two hours for a total of four doses, then every three or four hours. Take less frequently as symptoms abate.