Since I do not possess a medical degree and I know better than to play a doctor on the Internet these are merely suggestions and things I have heard along the way.
Calamine lotion (Granny recommended)
Cover the rash with a cotton cloth soaked in cool water and let a fan blow over it, according to The Doctors Book of Home Remedies.
Hydro cortisone cream
Topical antihistamines like lidocaine or benzocaine.
Oatmeal can dry up the oozing blisters.
Wear cotton it is easier on the irritated skin.
According to The Doctors Book of Home Remedies the most popular herbal treatment is jewelweed, also known as impatiens or touch me not, says Purdue University professor of pharmacognosy and author of The Honest Herbal
Use dish detergent and water within 30 minutes of contact to get the oil off your
your clothes, your dog and anything else that came in contact with the
plant. (This tip came from Healthwise Handbook - A Family Health Care
Manual distributed by Riddle Memorial Hospital). This may help prevent
or reduce the rash.