Rashes involve changes in the color or texture of your skin.
Often, the cause of a rash can be determined from its visible characteristics and other symptoms.
A simple rash is called dermatitis, meaning inflammation of the skin. Contact dermatitis is caused by things your skin touches, such as:
Chemicals in elastic, latex, and rubber products
Cosmetics, soaps, and detergents
Dyes and other chemicals in clothing
Poison ivy, oak, or sumac
Seborrheic dermatitis is a rash that appears in patches of redness and scaling around the eyebrows, eyelids, mouth, nose, the trunk, and behind the ears. If it happens on your scalp, it is called dandruff in adults and cradle cap in infants.
Age, stress, fatigue, weather extremes, oily skin, infrequent shampooing, and alcohol-based lotions aggravate this harmless but bothersome condition.
Other common causes of a rash include:
Eczema (atopic dermatitis) – tends to happen in people with allergies or asthma. The rash is generally red, itchy, and scaly.
Psoriasis – tends to occur as red, scaly, itchy patches over joints and along the scalp. Fingernails may be affected.
Impetigo – common in children, this infection is from bacteria that live in the top layers of the skin. Appears as red sores that turn into blisters, ooze, then crust over.
Shingles – a painful blistered skin condition caused by the same virus as chickenpox. The virus can lie dormant in your body for many years and re-emerge as shingles.
Childhood illnesses such as chicken pox, measles, roseola, rubella, hand-foot-mouth disease, fifth disease, and scarlet fever.
Medications and insect bites or stings.
Many medical conditions can cause a rash as well. For example:
Rheumatoid arthritis, especially the juvenile type