The symptoms of an allergic reaction to poison ivy usually appear 24 to 48 hours after contact with the sap. The first sign of an allergic reaction is a strong itching with redness at the site of contact.
Afterwards, lesions may appear and cause Inflammation, swelling, blistering and crusting when blisters burst and leak.
If your skin has come into contact with sap: Wash exposed areas with cold water as soon as possible, use a mild soap, make sure you remove all bits of the plant that could have been stuck under your nails and avoid rubbing your skin too hard.
For further information on allergic reactions to poison ivy, read Allergic Reactions caused by Poison Ivy. on the Portail santé mieux-être.