Contact dermatitis involves an inflammation of the skin caused by contact with a foreign substance. Common triggers of contact dermatitis include poison ivy, certain foods, cleaning products, detergents, cosmetics and latex rubber. When a patient comes in contact with one of these triggers, he/she may experience a red rash, blistering, itchiness, dryness and more. Symptoms caused by contact dermatitis may a result of an immune system reaction or from an external allergic reaction to the specific trigger.

Chronic actinic dermatitis is a rare skin condition that mainly affects men over the age of 50 years. It is characterized by severely itchy, red, inflamed, and thickened dry skin, mainly in areas that have been exposed to sunlight or artificial light. The condition is also known as chronic photosensitivity dermatitis and actinic reticuloid (this name comes from the histological findings of skin biopsies which resemble a reticulosis or cutaneous T-cell lymphoma).

The rash may develop in all areas exposed to the sun, with the face, neck, upper chest in a V distribution and backs of hands most commonly affected. The lesions are usually red and inflamed with scaling and lichenification (thickened and hardened patches of skin). The rash can be very itchy. The rash may spread to other areas of the body where the skin is covered by clothing.

The rash can be provoked by as little as 30 seconds exposure to daylight. It is condition that is often present throughout the year. Patients are at risk even on dull days and through window glass. Some of them also react to artificial light sources, especially naked fluorescent lamps.