One sign of poison oak rash is severe itching. Poison oak rash is a reaction to urushiol, an oil produced by the poison oak bush or plant. It is the same substance produced by poison ivy and poison sumac. Contact with urushiol causes a serious allergic reaction in 80% of people, but it usually does not affect animals.

What Does a Poison Oak Rash Look Like?
A poison oak rash is red, raised, swollen and blistering. Individual pustules will develop along red swollen lines where the plant brushed up against you. If you came in contact with urushiol from a pet or clothing, the rash may present in patches instead of lines. The rash will most likely itch maddeningly.

How Do You Know if It’s Poison Oak?
You can’t tell by looking at the rash if the reaction was caused by poison oak, poison ivy or poison sumac because all three rashes present the same symptoms. However, you can distinguish poison oak from bug bites and heat rashes by the fact that it will itch so much more than most any other rash and will most likely present in lines or patches. Bug bites are usually isolated and have one or two obvious bite entry points, whereas poison oak will look like a line or patch of pustules. Heat rashes may be raised, but the dots will be small in comparison with the larger blisters of poison oak.

How Soon After Contact Will a Posion Oak Rash Present?
Poison oak reactions can occur anywhere between an hour to a week after contact, but most reactions occur within four hours of contact. To prevent a poison oak rash, wear long sleeves and long pants, shower as soon as possible after possible contact using soap and hot water, and wash all clothing that may have come in contact with poison oak. Urushiol can remain active for up to year if left dry, so you’ll want to throw your gardening or lawn work clothes in the washer after every session of use in order to prevent repeated irritation.