itchiness

Itchiness, or pruritus, is an unpleasant sensation that provokes the urge to scratch. It is a symptom, not a disease, and can affect any part of the body. It may be localized to a small area or generalized.

Itch is mediated by specialized nerve fibers in the skin called pruriceptors, which transmit signals to the spinal cord and brain. Various mediators, such as histamine, cytokines, and neuropeptides, can trigger itch. In some conditions, itch persists despite the absence of a clear external trigger, a form known as chronic itch.

Common causes include dry skin, eczema, psoriasis, hives, allergic reactions, insect bites, fungal infections, dermatitis, and irritants. Systemic causes include kidney or liver disease, thyroid disorders, iron deficiency, certain cancers, pregnancy, and medication side effects. Psychological factors and stress can also contribute.

Diagnosis starts with history and physical examination. If the itch is persistent or widespread, clinicians may order blood tests, liver and kidney function tests, a skin biopsy, allergy testing, or imaging to identify underlying conditions.

Treatment focuses on identifying and addressing the underlying cause, relieving itching, and protecting the skin. Common approaches include regular moisturizing, avoiding irritants, and topical steroids or calcineurin inhibitors for inflammation; antihistamines for itch with an allergic component; and non-sedating or sedating options as needed. For chronic widespread itch, gabapentinoids, certain antidepressants, and other systemic therapies may be used. Phototherapy can help some people.

Prevention involves proper skincare, humidified environments, and avoiding known triggers. Seek medical attention for severe, persistent, or widespread itch, itching with fever, weight loss, jaundice, or a new rash that spreads rapidly, especially in children or older adults.