Indirect contact via smoke or animals with the resin on their fur can also cause the rash to appear. Signs and Symptoms Poison oak causes significant itching. The rash depends on the extent of exposure. Mild exposures lead to erythema or mild redness. The face and genitals are frequently involved because thin skin is more susceptible to contact allergy.
More intense exposures result in small to large blisters and uncomfortable swelling or edema.
Linear blisters or bumps are highly suggestive of poison oak. Without treatment the rash usually builds to a maximum over a few days to a week. The fluid from a weeping poison oak rash cannot spread the rash and is not contagious. Treatment Prevention works best. A product called Ivy Block provides an effective barrier against urushiol if you are going hiking or doing yard work.