A picture gallery displaying graphic images of poison oak rash is available at Healthline. Poison oak rash presents itself with red streaks or patches, which further develops into bumps and oozing blisters.
Allergic reactions to poison oak are usually noticeable within the first 24 to 48 hours after exposure though it can take as long as six days for symptoms to display, according to Healthline. The rash is generally at its worst about a week after exposure, and often lasts up to 12 days, with rare cases persisting over a month. Severe reactions require immediate medical attention, as they can be life-threatening. Most of the time, however, a poison oak rash can be treated at home.