Hello. I recently came in contact with poison ivy about a week ago. However, I went to urgent care and they thought it was shingles. I told the doctor I think it was poison ivy. I was in the yard pulling weeds and I ad short garden gloves and short sleeves. So I must have brushed up on it. However, I thought as soon as u touch it you immediately get the rash. I went to dermatology today. It is on my left lower arm area and around my lip area and upper righy cheek on my face. He gave me presodine to take for 12 days and benadryl cream and tablets for the itching. How soon should I see improvement on arm and especially face. Took the first tablets today. Is it true it takes 24 to 48 hours to actually see the rash. It did not show til about a day or 2 so that must be true.