A rash is a temporary eruption or discoloration of the skin and is often inflamed or swollen. Rashes come in many forms and levels of severity, and they last for different amounts of time. Some common causes of rashes include infections, which cover a wide range of illnesses. Skin rashes may be isolated to one area of the body as a reaction to something, such as a detergent or a piece of jewelry. Some conditions may create a skin rash no larger than a quarter, isolated to a single location, while other skin conditions create inflammation that can cover the entire body.

There are many skin rash causes, with the potential to contribute to chronic inflammation. Diseases linked to chronic inflammation include Alzheimer’s, cancer, anxiety, and depression. The rash associated with mycosis fungoides, a form of cutaneous T-cell lymphoma, is a mix of infiltrating cancer cells and the skin’s reaction to them. This condition can be slow-growing at first, lasting from months to years.

In the summer, common rashes like prickly heat can occur due to blocked sweat ducts, creating itchy bumps wherever the material blocks sweat escape. Cutaneous lupus has three types: Discoid lupus erythematosus (DLE), which causes a red rash that can leave scarring; Subacute cutaneous lupus erythematosus (SCLE), causing sores on sun-exposed skin; and Acute cutaneous lupus erythematosus (ACLE), which may also cause a widespread rash.

Autoimmune diseases occur when antibodies attack healthy tissues instead of harmful ones, affecting joints, internal organs, and skin. These include conditions like autoimmune skin disease and skin lupus.

Some rashes, like those caused by allergic reactions, can present as raised, red, pink, or flesh-colored welts that may hurt. Allergic reactions can be triggered by medicine, food, or environmental factors. Impetigo, appearing as rash and blisters often around the nose and mouth, is most common in babies and kids.

Understanding the various causes and treatments of skin rashes is crucial for proper care and management. For more information on rashes and their treatment, visit Harvard Health, Northwell Health, or Harvard Health’s guide on inflammation.