Urushiol, oil found on poison oak leaves, causes allergic contact dermatitis, which is not caused by allergic antibodies like true allergic reactions. Therefore, allergy shots do not work to prevent poison oak reactions, and there is no way to cure these types of reactions with pills or injections. Corticosteroids (especially oral or injected) taken prior to exposure to poison oak could prevent the reaction from occurring, but a person would have to take these medications each and every time they came into contact with poison oak. Unfortunately, corticosteroids have too many adverse side effects for a person to do such a thing.
If a person is planning on being in an area where contact with poison oak is likely, wearing pants, long-sleeved shirts, shoes and socks can prevent the plant oils from getting onto the skin. Applying Ivy Block to exposed skin, in much the same way that sunscreen is applied, may prevent the rash from occurring if used before contact with these plants. Lastly, washing with soap and water immediately after contact with poison oak may prevent or minimize that amount of rash that occurs.
Learn more about common causes of contact dermatitis.
Source:
Beltrani VS, Bernstein IL, Cohen DE, Fonacier L. Contact Dermatitis: A Practice Parameter. Ann Allergy Asthma Immunol. 2006;97:S1-38.
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