Itchy skin is at the very least a nuisance. When persistent and severe, this symptom can interfere with sleep and daily functioning. Itchiness is usually associated with skin disorders, but this symptom can also be caused by a wide variety of medical conditions. Infections, kidney and liver disease, hormonal disorders and certain cancers can cause itchy skin. A thorough medical history, physical examination and blood tests can help identify the cause, leading to appropriate treatment.
Many skin disorders can cause itchiness, known medically as pruritus. Eczema, a condition characterized by intense itchiness and dry, flaky skin, is one of the most common causes of itchy skin. Dry skin and psoriasis -- a skin disorder that leads to red, scaly patches -- are also frequent causes of pruritus. Contact dermatitis causes itchiness when the skin comes into contact with specific triggers, such as detergents, soaps, cosmetic products and plants, such as poison ivy and oak. An allergic response to certain foods or medications can also lead to itchy skin.
Many infections common during childhood -- including measles, rubella and chickenpox -- can cause itchy skin. These conditions are caused by viral infections and typically begin with flu-like symptoms accompanied by an itchy rash. Human immunodeficiency virus (HIV) is another viral infection linked to pruritus. HIV can lead to or aggravate itchy skin disorders, such as eczema. In some cases, however, itchiness may occur in people with HIV without an associated rash or obvious skin condition. Parasitic infestations, like scabies and lice, characteristically trigger localized, intense itchiness. Fungal infections, such as candida and ringworm, and bacterial skin infections due to staphylococcus or streptococcus can also cause itchy skin.
Cancer and Autoimmune Disorders
Itchy skin is sometimes a symptom of cancer. Cancerous tumors of the breast, ovaries and digestive tract have all been associated with itchiness. However, generalized itchiness is most commonly linked to leukemia and other blood cell cancers. In fact, pruritus may be the first symptom of Hodgkin lymphoma, a type of cancer involving blood cells called lymphocytes, report authors of an April 2013 article in "The New England Journal of Medicine." Autoimmune disorders cause the immune system to attack a person's own tissues. These disorders can lead to a number of symptoms, including itchiness. Lupus, rheumatoid arthritis and Sjogren syndrome are autoimmune conditions commonly associated with itchy skin.
Under normal circumstances, the kidneys filter a number of waste products from the blood. Kidney failure, which is most frequently caused by longstanding high blood pressure or diabetes, leads to accumulation of a metabolic waste product called urea. Urea and other substances that build up in the blood due to kidney failure often cause unrelenting itchiness. In addition, people with kidney failure often note itchiness following hemodialysis sessions used to treat kidney failure.
Liver disorders that significantly impair organ function frequently cause itchy skin. A buildup of bile -- a substance normally secreted by the liver into the intestines to help digest fatty foods -- is thought to trigger itchiness in people with liver disease. The autoimmune disorder primary biliary cirrhosis, gallstones that block bile flow from the liver and viral liver infections, such as hepatitis C, are commonly associated with pruritus. Certain antibiotics, steroids and birth control pills have also been linked to liver disease and itchy skin.
Hormonal conditions, including diabetes and thyroid disease, can result in itchiness. People with diabetes are prone to skin infections, and circulatory and nerve disorders that can cause itchiness. Disorders of the thyroid or parathyroid -- glands located in the neck that help regulate metabolism and calcium levels, respectively -- may also trigger intense itchiness. Pregnant women often report itchy skin as well. Normal weight gain during pregnancy can provoke skin itchiness, as can expected increases in estrogen levels. In rare cases, a pregnancy-related increase in estrogen can lead to bile accumulation and associated pruritus.
Neurologic disorders are often overlooked as possible causes of itchy skin. Irritation of the nerves that normally control the itch sensation can result in persistent itchiness. A pinched nerve due to arthritis or an injury, and nerve damage caused by multiple sclerosis or another neurologic inflammatory condition can lead to persistent pruritus. People who have experienced shingles, a painful rash caused by the virus responsible for chickenpox, can develop a condition called postherpetic neuralgia. Postherpetic neuralgia involves nerve damage that usually leads to pain but can also cause persistent itchiness. Brain tumors and stroke have also been linked to itchy skin.
Other Causes and Considerations
The list of medical conditions that can potentially provoke itchy skin is extensive. The reviewed examples cover the most likely causes, but there are many others. While itchy skin is often considered relatively inconsequential, anyone who has dealt with persistent or intense itchiness knows all too well how disruptive this symptom can be. See your doctor at your earliest convenience if you experience frequent, persistent, severe or disruptive itchiness. A variety of treatments are available, which vary depending on the underlying cause.
Reviewed and revised by: Tina M. St. John, M.D.