The best treatment for poison oak is to take short baths in lukewarm water and apply calamine lotion or hydrocortisone cream to the affected areas, advises the American Academy of Dermatology (AAD). Applying cool compresses to the skin and taking antihistamine medication helps to control itching.
Lukewarm baths using a colloidal oatmeal preparation can ease the itching of poison oak, according to the AAD. Adding a cup of baking soda to running bath water is also beneficial. Short showers in cool water ease the itch and discomfort of the rash.
Hydrocortisone creams and calamine lotion calm the skin following an outbreak of poison oak rash. A clean washcloth soaked in cold water is useful as a compress to soothe the itch brought on by the rash.
Once exposed to poison oak or other plants that contain urushiol, which is the oil that causes the rash associated with poison oak, poison sumac and poison ivy, it is important to wash the skin immediately using soapy water, explains AAD. This keeps the oil from spreading to other areas of the body or to other people. Wash clothing and anything that may have come into contact with the poison oak, such as gardening tools or pet fur.
A medical professional should evaluate a rash that does not improve within 10 days, warns the AAD. Immediate medical attention should be sought if the rash covers most of the body or the sufferer has trouble swallowing or breathing.