You\u2019ve probably had a rash at some point or another, whether from poison ivy or the chickenpox or something more unusual. Why does your skin break out in red blotches like that? More important, is there anything you can do about it?<\/p>\n
We often think of the skin as a barrier\u2014it keeps the insides of our bodies in, and it keeps the outside world out. But our skin is also filled with special cells of the immune system. These cells protect the skin and body against viruses, bacteria and other threats. Whenever these cells detect a suspicious substance, they begin a chain reaction in the skin that leads to inflammation. The medical name for this reaction is dermatitis. But it\u2019s more commonly known as a rash.<\/p>\n
There are many different types of dermatitis, and each has a distinct set of treatments. Sometimes the skin\u2019s immune cells react to something that directly touches the skin. Other times, the immune system flares in the skin because of a whole-body infection or illness.<\/p>\n
Itching<\/strong><\/p>\n The symptoms of these different types of rashes often overlap. \u201cItching is a common symptom for all these problems,\u201d says Dr. Stephen I. Katz, director of NIH\u2019s National Institute of Arthritis and Musculoskeletal and Skin Diseases. Many rashes are red, painful, and irritated. Some types of rash can also lead to blisters or patches of raw skin. While most rashes clear up fairly quickly, others are long lasting and need to be cared for over long periods of time.<\/p>\n Eczema, and atopic dermatitis<\/strong><\/p>\n Eczema, or atopic dermatitis, is a dry, red, itchy rash that affects up to 1 in 5 infants and young children. It often improves over time, although it can last into adulthood or start later in life. In this condition, the water-tight barrier between skin cells gets weak, which lets moisture out and other things in. That\u2019s why people with atopic dermatitis have to moisturize their skin, and they\u2019re more susceptible to skin infections.<\/p>\n Researchers have recently identified specific genes that are involved in maintaining the skin barrier. People with certain versions of these genes are more likely to get atopic dermatitis.<\/p>\n Allergic contact dermatitis<\/strong><\/p>\n \u201cThe skin is the outermost sentinel for fighting off bacteria and noxious agents,\u201d says Katz. \u201cIf the barrier is broken somehow, you can become more allergic to things.\u201d<\/p>\n A skin allergy, or allergic contact dermatitis, produces a red, itchy rash that sometimes comes with small blisters or bumps. The rash arises when the skin comes in contact with an allergen, a usually harmless substance that the immune system attacks. Allergens trigger allergic reactions. Allergens can come from certain soaps, creams and even pets.<\/p>\n Your immune system might not react the first time you encounter an allergen. But over time, your immune system can become sensitive to the substance. As a result, your next contact may lead to inflammation and an allergic rash.<\/p>\n \u201cThe most common form of dermatitis that is seen anywhere is an allergic contact dermatitis to nickel,\u201d says Katz. \u201cWhy? Because of ear piercing.\u201d Many inexpensive earrings are made of nickel, and over time, wearing nickel earrings can cause an allergic reaction to the metal.<\/p>\n Other common causes of allergic dermatitis are poison oak and poison ivy. The stems and leaves of these plants produce a chemical that\u2019s likely to cause allergies. If you touch one of them, wash your skin as soon as possible. The chemical can also remain in clothing for a long time, so it\u2019s important to wash any clothes or shoes\u2014or even pets\u2014that come into contact with these plants.<\/p>\n Mild cases of allergic contact dermatitis usually disappear after a few days or weeks. But if the rash persists, is extremely uncomfortable or occurs on the face, it\u2019s important to see a physician. A doctor can prescribe medications that will tone down the immune reaction in the skin. This eases swelling and itching and will protect your eyes and face.<\/p>\n Shingles<\/strong><\/p>\n The immune cells of the skin can also produce rashes when they react to invading germs\u2014like bacteria, fungi and viruses. Bacterial and viral infections within your body can cause your skin to break out in spots as well. The chickenpox virus, for example, can cause itchy spots in children. Years later, in older adults, the same virus may reappear as shingles, bringing a painful rash and high fever. Vaccines can prevent several rash-causing diseases, including chickenpox, shingles and measles.<\/p>\n Drug allergy<\/strong><\/p>\n Certain drugs, including antibiotics like amoxicillin, may also cause itchy skin rashes. If you\u2019re allergic to a drug, a rash can be the first sign of a serious reaction. As with other allergies, a reaction to a drug may not occur the first time you take it. It could show up after several uses. Not all drug rashes are due to an allergy, however. If you break out in itchy spots after starting a new drug prescription, contact your doctor right away.<\/p>\n