When a person comes into contact with poison ivy, they may experience an allergic reaction due to the presence of a resin called urushiol. While urushiol causes some form of allergic reaction in most people, only some of them will have a medical emergency. The allergic response as a result of contact with poison ivy is an IgE allergy. This means that it’s a ‘true’ allergy wherein immune cells create and spew out inflammatory mediators. Interestingly enough, poison ivy reactions may occur only after the second (or more) exposure to the poison ivy plant. Is is also possible to experience a mild reaction one year and a more sever reaction the following year. Recommendations for poison ivy are the same as with any other allergy. If you know you have a severe allergic response to an allergen (peanut, bee stings, poison ivy) then you have to avoid exposure to it. If needed, you should carry an epi-pen for medical emergencies.