Many people get a rash from poison ivy, poison oak, and poison sumac. The itchy, blistering rash often does not start until 12 to 72 hours after you come into contact with the oil. The rash is not contagious and does not spread. It might seem to spread, but this is a delayed reaction.
Moreover, how long can poison ivy stay on clothes?
It is not unusual for urushiol to stay active on any surface, including dead plants, for one to five years. It does not evaporate like a water-based substance, so it can stay active on things like clothes and tools; if you come in contact with any such item, you will be exposed to urushiol oil all over again.
How long does it take to show signs of poison ivy?
If you're allergic to poison oak, signs will begin to appear 1 to 6 days after exposure. Most of the time, you'll notice it within the first 24 to 48 hours. The most obvious evidence of an allergic reaction is skin rash, also called dermatitis.