Contact dermatitis is caused by an allergic reaction to a chemical present in leaves, flowers, plants, or chemicals in a product. Contact allergic reactions are different than acute reactions in their mechanism. Contact allergy causes skin rashes in about 48 to 72 hours after exposure. Migration of immune cells to the area of contact and release of products of inflammation lead to redness, itching, swelling, and at times pustules appear around the area of contact.
Poison ivy is one of the most common causes of allergic skin reaction in USA. The skin reaction due to poison ivy allergy is known as poison ivy dermatitis. People with allergic to poison ivy can also experience a reaction also to poison oak, mango, cashew, and Ginko. Poison ivy plant is identified by leaves being in groups of three or more leaves. It is important to be able to recognize the plant so that you can avoid exposure to them. The plant starts appearing in spring and continue to be there until late fall as wines climbing on trees.
Is poison skin rash contagious? This is a very common question asked especially from school teachers, to decide if the affected children need to stay home. Poison ivy rashes are not contagious. The symptoms develop only on those who are allergic to Urushiol present in the plant. The reaction to poison ivy start reaction within 2-4 days of exposure. The dermatitis can vary from a mild rash to a localized area of contact to formation of blisters affecting large areas of the body. Often the exposed areas such as face and arm are affected, and it may show a linear pattern of rash based on the contact. Very sensitive individuals can be affected by even burning of wood with poison ivy on them.