A rash is a change of the skin which affects its color, appearance or texture. A rash may be localized in one part of the body, or affect all the skin. Rashes may cause the skin to change color, itch, become warm, bumpy, dry, cracked or blistered, swell and may be painful. The causes, and therefore treatments for rashes, vary widely. Diagnosis must take into account such things as the appearance of the rash, other symptoms, what the patient may have been exposed to, occupation, and occurrence in family members. The diagnosis may confirm any number of conditions.

The presence of a rash may aid associated signs and symptoms are diagnostic of certain diseases. For example, the rash in measles is an erythematous, maculopapular rash that begins a few days after the fever starts. It classically starts at the head and spreads downwards.

Common causes of rashes include:

• Anxiety
• Allergies, for example to foods, dyes, medicines, insect stings, metals such as zinc or nickel; such rashes are often called hives.
• Skin contact with an irritant
• Bacterial or viral infection, e.g., by the viruses that cause chickenpox, smallpox, cold sores and measles
• Fungal infection, such as ringworm
• Reaction to vaccination
• Skin diseases such as eczema or acne
• Exposure to sun (sunburn) or heat
• Friction due to chafing of the skin
• Irritation such as caused by abrasives impregnated in clothing rubbing the skin. The cloth itself may be abrasive enough for some people
• Menstruation

Did you know?

• Although rashes are seldom dangerous, self-diagnosis is not usually a good idea.
• The word "rash" does not have an exact meaning or refer to a specific disease or kind of disorder. It's a general term that means an outbreak of bumps on the body that changes the way the skin looks and feels.
• The rash of scarlet fever becomes confluent and forms bright red lines in the skin creases of the neck, armpits and groins.
• Typically, it is never a good habit for one to scratch a rash, as doing so may invigorate the rash and cause it to spread.
• Gently rubbing the rash may provide temporary relief, but it is more than likely better to avoid contact with the affected areas altogether.