MedlinePlus, an online medical encyclopedia sponsored by the U.S. National Library of Health, describes a skin rash as any condition in which the color or texture of the skin is altered. The unifying characteristic of all skin rashes is inflammation, which can cause skin redness and swelling. Doctors can often identify the cause of a rash based on its appearance and location. There are several different types of skin rashes, each of which have distinct causes.
Contact Dermatitis
One very common type of skin rash is contact dermatitis. The term "dermatitis" refers to inflammation of the skin, and "contact" refers to the fact that the rash is caused by an external substance that this skin touches. MedlinePlus notes that there are several types of contact dermatitis, which are caused either by irritation and/or an allergic reaction caused by the substance. These types include poison ivy, oak, and sumac; make-up, perfumes, detergent, and soap; various chemicals that come into contact with the skin, often through clothing; metals such as nickel; and latex and rubber.
The symptoms of contact dermatitis are skin redness, swelling, and tenderness; itching; lesions on the skin that may ooze or become crusty; and skin that becomes scaly or thick.
Seborrheic Dermatitis
Seborrheic dermatitis is a chronic skin rash characterized by inflammation that causes the skin to flake off, according to the Penn State Milton S. Hershey Medical Center. This type of skin rash commonly occurs on the face, scalp and behind the ears. Seborrheic dermatitis on the scalp is commonly known as dandruff. Though the specific cause of this rash is not yet known, though it does seem to be hereditary and children of parents with this type of skin rash are more likely to be affected. A fungus that infects the hair follicles may also have a role in causing this skin rash.
Autoimmune Rash
An autoimmune rash is caused by the immune system response that inappropriately attacks the skin, rather than invading microbes as intended with the immune system. Two common types of autoimmune rashes are psoriatic rash and a lupus rash. Psoriasis causes areas of pink raised areas covered by silver scaly skin, and surrounded by red borders, according to the University of Maryland Medical Center.
The Lupus Foundation of America describes lupus as another autoimmune disease that causes a skin rash. A common manifestation of this disease is a "butterfly rash." The butterfly rash is a raised or flat rash that covers the cheeks and extends over the bridge of the nose. The color of this rash ranges from bright red to mild pink.
