Contact dermatitis of the foot is an inflammation of the skin in response to an irritant. This irritant is something with which the foot has come into contact, such as materials and chemicals with which shoes are made, poison ivy or harsh chemicals. When the skin of the foot comes into contact with the substance, an allergic response is initiated. Symptoms, including redness, itchiness and small blisters, usually occur within 24 hours of exposure to the irritant. The symptoms should be evaluated by a foot and ankle surgeon for proper diagnosis and treatment.