Reasons for Itching Under Skin

Itchiness, or pruritus, most commonly occurs due to a skin condition with visible signs such as a rash, dry patches, hives or blisters. In some cases, however, itching sensations occur without any skin abnormalities. Many people describe this as itchiness occurring under the skin as opposed to on the skin surface, but the sensation occurs within the skin in both cases. Itchiness under the skin occurs with a broad array of diseases and conditions, ranging from medication reactions to cancer.

Liver Disease

Widespread itchiness frequently occurs in people with liver disease, especially ailments that involve blockage of bile flow through the liver and gallbladder into the intestine. The mechanism by which liver disease leads to itchy skin remains incompletely understood but appears to involve a combination of biochemical derangements. Treatment leading to resolution of the underlying liver disease typically leads to disappearance of the related itchiness. In people with ongoing liver disease, however, treatment is directed at symptom relief.

Chronic Kidney Disease

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According to a July 2011 article published in "American Family Physician," more than half of people with chronic kidney disease experience persistent itchiness, including up to 80 percent on those on dialysis 3. The itchiness usually occurs all over but may be most intense on the back. This type of itchiness, known as uremic pruritus, is thought to occur due to the buildup of toxins in the skin caused by severely impaired kidney function.

Cancer and Blood Disorders

Generalized itchiness can occur with a variety of organ and blood cancers. This symptom occurs most frequently with non-Hodgkin lymphoma, sometimes preceding the diagnosis by a year or more. Itchy skin might also occur with leukemia, multiple myeloma, and cancer of the lung, prostate, colon, breast, brain, cervix, uterus or stomach. People with iron deficiency anemia and those who produce too many red blood cells also sometimes experience skin itchiness.

Nervous System Diseases and Conditions

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Itch sensations occur when nerves that carry these signals fire. Nervous system diseases and conditions that affect itch nerves can lead to misfiring and skin itchiness. Examples of these conditions include:

• Multiple sclerosis
  
• Peripheral neuropathy, such as frequently occurs with diabetes and HIV
• Nerve compression syndromes
• Nervous system tumors

Medication Side Effects

Certain medications can cause generalized itchiness as a side effect. Up to 10 percent of people taking oral opioid pain relievers develop this side effect, according to an October 2006 "American Family Physician" article 36. Examples of other medications that can potentially cause itchy skin include:

• Estrogen: used in hormonal contraceptives and hormone replacement therapy
• Angiotensin-converting enzyme (ACE) inhibitors: used to treat high blood pressure and heart failure
  
• Hydrochlorothiazide: a water pill used to treat high blood pressure and heart failure

Other Causes

A variety of other conditions and disorders might cause unexplained skin itchiness, including:

• Pregnancy
  
• Diabetes
• Overactive or underactive thyroid
• Celiac disease
• Certain parasitic infestations
• HIV/AIDS
• Depression, obsessive compulsive disorder, anxiety disorder or schizophrenia

Although not life threatening, persistent itchiness can significantly affect quality of life by disrupting your work, daily activities and sleep. As there are many possible causes, see your healthcare provider if you're experiencing this symptom. After determining the cause, your doctor will recommend a treatment plan. In most cases, this involves oral medication to interrupt or decrease the transmission of itch signals to and from the skin.

Reviewed and revised by: Tina M. St. John, M.D.