<unk>  is a localized rash or irritation of the skin caused by<unk>  with a foreign substance. Only the superficial regions of the skin are affected in<unk> . Inflammation of the affected tissue is present in the epidermis (the outermost layer of skin) and the outer dermis (the layer beneath the epidermis).<unk>  results in large, burning, and itchy rashes. These can take anywhere from several days to weeks to heal. This differentiates it from<unk>  urticaria (hives), in which a rash appears within minutes of exposure and then fades away within minutes to hours. Even after days,<unk>  fades only if the skin no longer comes in<unk>  with the allergen or irritant. Chronic<unk>  can develop when the removal of the offending agent no longer provides expected relief. Irritant dermatitis is usually confined to the area where the trigger actually touched the skin, whereas allergic dermatitis may be more widespread on the skin. Irritant dermatitis usually found on hands whereas exposed areas of skin. Symptoms of both forms include the following: *Red rash. This is the usual reaction. The rash appears immediately in irritant<unk> ; in allergic<unk> , the rash sometimes does not appear until 24–72 hours after exposure to the allergen. *Blisters or wheals. Blisters, wheals (welts), and urticaria (hives) often form in a pattern where skin was directly exposed to the allergen or irritant. *Itchy, burning skin. Irritant<unk>  tends to be more painful than itchy, while allergic<unk>  often itches. *The surface appearance of skin is dry and fissured in the irritant<unk>  whereas vesicles and bullae are seen in allergic<unk> . *lichenified lesions. While either form of<unk>  can affect any part of the body, irritant<unk>  often affects the hands, which have been exposed by resting in or dipping into a container (sink, pail, tub, swimming pools with high chlorine) containing the irritant.
Contact dermatitis
Angioedema
Autosensitization dermatitis
Atrophic vaginitis
Phototoxic tar dermatitis
Allergic contact dermatitis
Drug eruption
Rodent mite dermatitis