What Is a Rash?

Rash is a general, nonspecific term that describes any visible skin outbreak. Rashes are very common in all ages, from infants to seniors, and nearly everyone will have some type of rash at some point in their life. There are a wide variety of medical diagnoses for skin rashes and many different causes.


While there are many different types, rashes may basically be divided into two types: infectious or noninfectious.

  • Noninfectious rashes include contact dermatitis (caused by your skin coming into contact with poisonous plants, latex, soaps, cosmetics, lotions, etc.), eczema, hives, and dry skin
  • Infection-associated rashes may be caused by ringworm, scabies, herpes, chickenpox, and shingles. Infectious agents that can also cause a rash include viruses, bacteria, fungi, and parasites.


Most rashes tend to be itchy, although some, especially the most serious, may be painful or burning.


The need for medical treatment often depends on what other symptoms are present. A rash that occurs with other symptoms, such as shortness of breath or fever, may mean another problem, such as a serious allergic reaction or infection.

In general, most noninfectious rashes are usually treated symptomatically and often with cortisone creams and/or pills. Infection-associated rashes are frequently treated by addressing the underlying infection.

A very rare and serious type of generalized red rash is toxic epidermal necrolysis (TEN). This rash may cause the skin to peel away, leaving large areas of tissue that weep or ooze fluid like a severe burn. If this type of rash occurs, you need to see a doctor. TEN may occur after the use of some medicines.

Determining the specific cause of rash usually requires a description of the skin rash, including its shape, arrangement, distribution, duration, symptoms, and history. All of these factors are important in identifying the correct diagnosis. Accurate information about past treatments, successful and unsuccessful, is very important. Treatments that work may be a clue to the cause of the rash, may mask symptoms, or change the appearance, making a definite diagnosis harder. Sometimes good quality pictures of an earlier stage of the rash may aid diagnosis. There are many useful laboratory and special examinations that can be helpful in the diagnosis of rash as well.