Wearing gloves, long pants and sleeves can prevent contact with the plant, but if the allergen is present on your clothing, you can develop a rash from that contact. You can also come in contact with the allergen by petting a cat or dog who has walked through the weeds. Stokoguard is a barrier cream that can also protect your skin from coming in contact with the allergen. The allergen remains active for up to a year on clothing, tools and wood. The rash can be treated with topical cortisone preparation or cortisone pills.
Antihistamines can relieve some of the itching.
Contrary to popular beliefs, the fluid in the blister will not spread the rash. The allergen is not present in the blister fluid. The rash may appear to spread because areas with more allergen will develop a rash before other areas that have less allergen. You cannot develop poison ivy except by contact. This contact, however, may occur from smoke when the weed is burned.