Some Causes and Features of Itching
Cause | Common Features* | Tests |
|---|---|---|
Skin causes | ||
Atopic dermatitis (sometimes called eczema) | Dryness, redness, and sometimes thickening and scaling, often in the folds of the elbows or behind the knees Usually a family history of allergies or rashes | A doctor's examination |
Redness and sometimes blisters in a shape or location corresponding to the substance causing the reaction (such as along the hairline when caused by hair dyes, on the wrist when caused by a watch, or on exposed skin when caused by poison ivy) | A doctor's examination | |
Dry, itchy, scaly skin, usually on the legs, that is worsened by dry heat and develops or becomes worse in winter, after a hot bath, or after prolonged exposure to water | A doctor's examination | |
Fungal skin infections, such as ringworm, jock itch, or athlete's foot | A circular rash with raised scaly borders In adults, usually on the feet or genital area In children, usually on the scalp or body | Sometimes examination of skin scales under a microscope |
Hives (urticaria) | Red, raised swellings that have sharp borders and are often pale in the center Hives go away within hours (usually less than 24 hours), but new hives continue to appear, sometimes for days to months | Usually only a doctor's examination |
Sudden appearance of one or a few bumps that are usually small, red, and raised | A doctor's examination | |
Lice infestation (pediculosis) | Areas of scratched, irritated skin and sometimes tiny, pinpoint bites Eggs (nits) and sometimes lice Usually in the scalp, armpits, or pubic area or on the waist or eyelashes | A doctor's examination |
Areas where repeatedly scratched skin has thickened Areas are red, scaly, raised, rough, and separated from surrounding skin | A doctor's examination | |
Raised red patches with silver scales Usually on the outer exposed surface of the elbows or knees or on the scalp or trunk | A doctor's examination | |
Burrows, which are small red or dark bumps, next to a fine, wavy, slightly scaly short line Usually in the web spaces between the fingers or toes, along the belt (waist) line, on the inner surfaces of the elbows, behind the knees, around the nipples (in women), or near the genitals (in men) | Sometimes examination of skin scales or debris under a microscope | |
Systemic causes (conditions that affect more of the body than just the skin) | ||
Allergic reactions that have skin and internal effects | Widespread itching Often a raised red rash and sometimes hives | Avoiding things one at a time to see what the cause is Sometimes skin testing |
Cancer, such as Hodgkin lymphoma, certain other lymphomas such as mycosis fungoides, and polycythemia vera | Itching sometimes as the first symptom of cancer With Hodgkin lymphoma, burning with itching, particularly in the legs With mycosis fungoides, various raised or flat skin patches or reddening of the skin With polycythemia vera, itching after bathing but without a rash | A complete blood count A chest x-ray A biopsy of lymph nodes for Hodgkin lymphoma, of skin for mycosis fungoides, or of bone marrow for polycythemia vera |
Widespread itching and no rash Sometimes worse during dialysis | Tests of kidney function | |
Frequent urination, thirst, and weight loss Itching usually occurring only after other symptoms have developed | Blood and urine tests for level of sugar (glucose) and glycosylated hemoglobin (which indicates the level of blood sugar over time) | |
Sometimes no rash | A doctor's examination | |
Gallbladder or liver disorders | Other symptoms of gallbladder or liver disorders, such as jaundice, fatigue, oily stools, and abdominal pain | Usually blood tests to measure liver enzymes and abdominal ultrasonography |
Intense itching that comes and goes Other symptoms of multiple sclerosis, such as numbness and tingling, weakness, loss of vision, vertigo, and clumsiness | Magnetic resonance imaging (MRI) of the brain, spinal cord, or both Sometimes a spinal tap Sometimes electroencephalography or electromyography | |
Pregnancy | Usually widespread itching without rash, developing sometimes in late pregnancy (called cholestasis of pregnancy) Sometimes resulting from mild liver problems | Sometimes blood tests to check for a liver disorder |
Psychologic factors (psychogenic itching) | Linear skin scratches and/or scabs in different stages of healing, and a psychologic disorder (such as depression or anxiety) | Tests to exclude other causes of itching, based on the person's symptoms |
Thyroid disorders | With hyperthyroidism (an overactive thyroid gland): Difficulty tolerating heat, sweating, weight loss, bulging eyes, shakiness (tremor), restlessness, and sometimes an enlarged thyroid gland (goiter) With hypothyroidism (an underactive thyroid gland): Difficulty tolerating cold, weight gain, dry skin and hair, and depression | Blood tests to evaluate thyroid function |
* Features include symptoms and results of the doctor's examination. Features mentioned are typical but not always present. | ||