What is itching?
Itching is elicited by the physical or chemical stimulation of nerve receptors in the skin. It can be caused by a wide variety of problems in a variety of different organ systems.
Nearly any skin lesion may itch. Skin-related causes include varied problems such as eczema, psoriasis, contact dermatitis, insect bites, bacterial infections, fungal infections, sunburn, and exposure to wool. Viral infections such as chickenpox can cause intense itching. Itching of the eyes and nose is commonly associated with allergies. Itching without a skin rash may be caused by a number of internal problems. Various endocrine problems in children associated with itching include liver disease, kidney failure, thyroid disease, and diabetes. Some malignancies, particularly lymphomas, may cause itching. Hookworms and pinworms are both internal causes of itching, as are certain drugs. Some women experience generalized itching during pregnancy.
Certain psychiatric problems are associated with itching. Patients may scratch hard enough to create deep ulcers. The intensity of the itching seems to be related to the degree of nervous tension. In addition, patients who suffer from certain psychotic states or those who abuse drugs such as cocaine may experience a deep itching sensation that they describe as bugs crawling beneath the skin.
Itching may rarely be associated with neurologic disease in which changes in sensation are interpreted by the patient as itching. Occasionally, circulatory problems will cause itching, primarily on the legs. Both of these conditions are more common in older adults than in children or young adults.
Treatment should be directed toward the cause of the itching. Hydration (bathing followed by moisturizing lotion) may be helpful in providing relief. When itching is the result of an allergen such as poison ivy, however, a drying agent should be used. Various medications (primarily antihistamines) may relieve itching, but most also cause significant sleepiness.
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