Any of the purified derivatives of the coca plant extract ... get an OTC spray of lidocaine or benzocaine meant for sunburn. Because no herbal anything can deal with urishiol.

She needs to wash carefully with mild soap to remove the oily irritant (anyone helping her should wear gloves and be careful), then apply the coca plant derivative spray as needed.

Keep the rashy area clean and dry, watch for secondary infections.

I am very sensitive to the stuff. If it gets too bad have her talk to her doctor about a high dose prednisone regimen. That will provide almost instant relief. I keep a large bottle of Tecnu in my bathroom and use liberally when I encounter it, can prevent rash if used in an hour or two.

If you can find jewelweed, I found it to be very effective in dealing with poison ivy. You have to find the plants fresh, because it is the juicy flesh and stems that provide the benefit.

Where I live jewelweed is often in cross proximity to poison ivy. When I have contact with poison ivy, I apply jewelweed juice from crushed stems immediately, and avoid developing a rash.

This worked for me - http://herbvive.com/product/hylands-poison-ivy-oak---50-tablets