Rashes occur for a variety of reasons, some relatively benign, some extremely serious. Many rashes look similar to one another so their causes may be difficult to diagnose.
Contact dermatitis is caused by an irritating substance. In some cases, the substance is universally irritating, like certain chemicals. In others, the irritation is the result of an allergen, such as latex, perfume, dye, or animal dander, that irritates only individuals with particular sensitivities. Plants like poison ivy and insect bites cause rashes in some individuals.
Apart from contact dermatitis, patients may develop allergic rashes as a reaction to ingested allergens. Certain food stuffs and medications can trigger hives or other rashes in sensitive individuals.
Seborrheic dermatitis occurs when the skin forms red, scaly, flaking patches. Though most common on the face and on the head, where it is known as dandruff or cradle cap, the condition can also be evident in the outer ear, on the eyebrows or eyelashes, forehead, sides of the nose, or chest and upper back.
Viral Or Bacterial Skin Conditions
Other skin conditions, like eczema, psoriasis, impetigo, or pityriasis rosea, frequently cause rashes. Each may be diagnosed by its pattern, whether the rash is flat or pustular, and on what part of the body it occurs, although distinguishing the rashes may at times be difficult.
Many systemic diseases have rashes as one of their symptoms. These include disorders often characterized as childhood diseases, like measles, chicken pox, rubella and scarlet fever, shingles, a disease caused by the same virus that is responsible for chicken pox, autoimmune diseases such as rheumatoid arthritis and lupus, and some sexually transmitted diseases, such as syphilis.
Rashes Caused By Sun Or Heat
Heat rash is a common ailment in infants, but can occur in individuals of any age, causing small red spots or bumps which may be itchy. This rash develops when the sweat ducts in the skin are clogged, interfering with the normal process of perspiration. Too much exposure to the sun to the ultraviolet light of tanning salons may also cause a rash on affected areas. This type of rash is sometimes referred to as “sun poisoning” but the scientific name for it is polymorphous light eruption or PMLE.
Under certain circumstances, some individuals may develop rashes from stress alone, without another precipitating cause.