How can i get rid of poison ivy, oak, sumac fast?

Poison Ivies: There are specific products that you can buy that will wash the Urushiol off. Some options of treating poison ivies include calamine lotion, oatmeal soaks, Hydrocortisone cream and antihistamines. Anything which has touched urushiol from the poison ivy needs to be cleaned (clothes, shoes, gear etc.) Oral steroids are sometimes indicated.

Systemic steroids: The urushiol of poison ivy soon penetrates the epithelium of the skin and covalently bonds to proteins and cannot be removed. Within 3-5 days, the allergic reaction peaks, lasting 3-6 weeks: itching, redness, swelling, blistering/bubbling, weeping all very characteristic and seen with most people who become exposed. Topical steroids, antihistamines, calamine help a little. Get seen.

Allergic Dermatitis: If you are referring to getting rid of a rash caused by these plants then the proper treatment is topical corticosteroids for mild/moderate cases. For severe, generalized cases oral prednisone is the best option.