Allergic contact dermatitis is a sudden onset skin rash from skin exposure to substance the body has mounted an allergic response to over repeated exposures. The rash develops at the point of skin contact, and the rash will become worse with each future exposure. The skin rash can appear as redness, flakiness, blisters, or open weeping areas. Occasionally, pigmentation or brown discoloration can occur following skin healing from the initial dermatitis. Nickel (from jewelry, jean buttons), poison ivy (oak, and sumac), neomycin (in Neosporin® antibiotic ointment), fragrances & dyes (in perfume, cosmetics, and hair dyes), and formaldehyde (in acrylic nails and clothing) are just some of the causes of allergic contact dermatitis. Patients with eczema are at higher risk for developing allergic contact dermatitis. Patch testing is done on the skin to try and determine the cause of allergic contact dermatitis. Treatment consists of avoiding known causes of allergic contact dermatitis, as well as topical treatment, usually with coriticosteroids. Fragrance-,dye-, and chemical-free soaps and moisturizers are often used in combination with prescription medications to improve the skin barrier and repair the skin. Red diode light, called the Healite II, can be used in the days following contact dermatitis to decrease the redness and inflammation of the skin. A specific type of contact dermatitis related to plants is termed phytophotodermatits. Phyto- means plant, photo- means light, and dermatitis means inflammation of the skin. Therefore, this reaction occurs when the skin comes in contact with juices from certain fruits and plants, followed by exposure to sun or light, causing an inflammatory reaction on the skin. Lime (from fruit juices or margaritas) are a common culprit, although parsley, parsnip, fennel, mustard, fig leaves, and St. John's wort may also cause the reaction. The skin often exhibits redness and swelling, and sometimes a blistering reaction. Once this subsides, brown discoloration often appears, which may last for weeks to months. Beyond treatment of the skin eruption, sunscreen plays an important role in minimizing pigmentation following the rash.