Itching can be very uncomfortable. It is one of the most common reasons people see dermatologists. Itching can be triggered by wool fibers or irritants, such as solvents or cosmetics.

Itching can result from disorders that affect the skin, the nervous system (which senses itching), or other parts of the body (such as bile ducts or kidneys) or from drugs. Causes that affect more of the body than just the skin are called systemic causes.

Itching makes people want to scratch. Scratching temporarily relieves itching but can damage the skin, sometimes resulting in more itching or infection. Over time, the skin can become thick and scaly.

When the Skin Is Dry
Normal skin owes its soft, pliable texture to its water content. To help protect against water loss, the outer layer of skin contains oil, which slows evaporation and holds moisture in the deeper layers of skin. If the oil is depleted, the skin becomes dry. Dry skin (xerosis) is common, especially among people past middle age. Common causes are cold weather and frequent bathing. Bathing washes away surface oils, allowing the skin to dry out. Dry skin may become irritated and often itches—sometimes it sloughs off in small flakes and scales. Scaling most often affects the lower legs. Rubbing or scratching dry skin can lead to infection and scarring. Dry Skin A form of severe dry skin is called ichthyosis. Ichthyosis can be an inherited disorder or can result from a number of other disorders, such as an underactive thyroid gland (hypothyroidism), lymphoma, and AIDS. The key to treating simple dry skin is keeping the skin moist. Taking fewer baths allows protective oils to remain on the skin. Moisturizing ointments or creams containing petroleum jelly, mineral oil, or glycerin can also hold water in the skin. Harsh soaps, detergents, and the perfumes in some moisturizers irritate the skin and may further dry it. When scaling is a problem, solutions or creams containing salicylic or lactic acid or urea may help remove the scales. For some forms of severe ichthyosis, creams containing substances related to vitamin A, such as tretinoin, help the skin shed excessive scales.

Causes

The most common causes of itching are related to skin disorders:

• Dry skin
• Eczema (also called atopic dermatitis)
• Contact dermatitis (an allergic rash resulting from direct contact with a particular substance)
• Fungal skin infections

Systemic causes are less common but are more likely if there is no visible skin problem. Some of the more common systemic causes are

• Allergic reactions that have internal effects—for example, to foods, drugs, bites, or stings (internal allergic reactions)
• Disorders of the gallbladder or liver, such as gallstones
• Chronic kidney disease

Less common systemic causes include an overactive thyroid gland (hyperthyroidism), an underactive thyroid gland (hypothyroidism), diabetes, iron deficiency, and polycythemia vera (a cancerous overproduction of red blood cells). Drugs can cause itching by causing allergic reactions. Drugs can also cause itching without causing an allergic reaction. For example, morphine and some radiopaque dyes given by vein (intravenously) may cause itching.

Evaluation

Not every episode of itching requires immediate evaluation by a doctor. The following information can help people decide whether a doctor's evaluation is needed and help them know what to expect during the evaluation. Most conditions causing itching are not serious.

Warning signs: The following may indicate that the cause could be serious:

• Weight loss, fatigue, or night sweats—symptoms that may indicate a serious infection or a tumor
• Weakness, numbness, or tingling—symptoms that may indicate a nervous system disorder
• Abdominal pain or a yellowish discoloration of the skin and eyes (jaundice)—symptoms that may indicate a gallbladder or liver disorder
• Excessive thirst, abnormally frequent urination, and weight loss—symptoms that may indicate diabetes

When to see a doctor: People who have weight loss, fatigue, or night sweats should see a doctor as soon as convenient, probably within a week or so. People with any of the other warning signs or with severe itching should probably see a doctor immediately or as soon as possible.

What the doctor does: Doctors ask many questions and look at the skin. Often, a person needs to undress so that the entire skin surface can be checked. If no clear cause is found after checking the skin, doctors may do a complete physical examination to check for systemic causes. Testing may be necessary to diagnose certain systemic causes and sometimes skin disorders.

If itching is widespread and begins shortly after use of a drug, that drug is a likely cause. If itching (usually with a rash) is confined to an area in contact with a substance, particularly if the substance is known to cause contact dermatitis, that substance is a likely cause. However, allergic causes of widespread itching can be difficult to identify because affected people have usually eaten several different foods and have been exposed to many substances that could cause an allergic reaction before itching develops. Similarly, identifying a drug that is causing the reaction in a person taking several drugs may be difficult. Sometimes the person has been taking the drug causing the reaction for months or even years before a reaction occurs.

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Some Causes and Features of Itching Cause Common Features* Tests Skin causes Contact dermatitis 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 skin Dry, scaly skin, usually on the legs, that develops or becomes worse in winter, after a hot bath, or after prolonged exposure to water A doctor's examination Eczema (atopic dermatitis) 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 Fungal skin infections, such as ringworm, jock itch, or athlete's foot A circular rash with raised borders, scaling, and often hair loss 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 clear in the center Each hive resolving within hours, but new hives continuing to appear, sometimes repeatedly Usually only a doctor's examination Insect bite 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 Usually in the scalp, armpits, or pubic area or on the waist or eyelashes Sometimes examination of skin scales or debris under a microscope Lichen simplex chronicus Areas where repeatedly scratched skin has thickened Areas are red, scaly, raised, rough, and separated from surrounding skin A doctor's examination Psoriasis 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 Scabies 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 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 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 Chronic kidney disease Widespread itching and no rash Sometimes worse during dialysis and sometimes worse on the back Tests to exclude other causes of itching, based on the person's symptoms Diabetes Frequent urination, thirst, and weight loss Itching usually occurring only after other symptoms have developed Blood tests for level of sugar (glucose) and glycosylated hemoglobin (which indicates the level of blood sugar over time) Drugs, such as aspirin, barbiturates, cocaine, morphine, penicillin, and some antifungal and chemotherapy drugs 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 ultrasonography Iron deficiency anemia Tendency to tire easily Sometimes paleness, weakness, or difficulty breathing Blood tests for anemia and iron deficiency Multiple sclerosis 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 Sometimes resulting from mild liver problems Sometimes blood tests to check for a liver disorder Psychologic factors Linear skin scratches and/or scabs in different stages of healing, and psychologic symptoms 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, coarse and thick skin, and sluggishness Blood tests to evaluate thyroid function *Features include symptoms and results of the doctor's examination. Features mentioned are typical but not always present. Some Causes and Features of Itching Cause Common Features* Tests Skin causes Contact dermatitis 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 skin Dry, scaly skin, usually on the legs, that develops or becomes worse in winter, after a hot bath, or after prolonged exposure to water A doctor's examination Eczema (atopic dermatitis) 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 Fungal skin infections, such as ringworm, jock itch, or athlete's foot A circular rash with raised borders, scaling, and often hair loss 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 clear in the center Each hive resolving within hours, but new hives continuing to appear, sometimes repeatedly Usually only a doctor's examination Insect bite 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 Usually in the scalp, armpits, or pubic area or on the waist or eyelashes Sometimes examination of skin scales or debris under a microscope Lichen simplex chronicus Areas where repeatedly scratched skin has thickened Areas are red, scaly, raised, rough, and separated from surrounding skin A doctor's examination Psoriasis 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 Scabies 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 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 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 Chronic kidney disease Widespread itching and no rash Sometimes worse during dialysis and sometimes worse on the back Tests to exclude other causes of itching, based on the person's symptoms Diabetes Frequent urination, thirst, and weight loss Itching usually occurring only after other symptoms have developed Blood tests for level of sugar (glucose) and glycosylated hemoglobin (which indicates the level of blood sugar over time) Drugs, such as aspirin, barbiturates, cocaine, morphine, penicillin, and some antifungal and chemotherapy drugs 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 ultrasonography Iron deficiency anemia Tendency to tire easily Sometimes paleness, weakness, or difficulty breathing Blood tests for anemia and iron deficiency Multiple sclerosis 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 Sometimes resulting from mild liver problems Sometimes blood tests to check for a liver disorder Psychologic factors Linear skin scratches and/or scabs in different stages of healing, and psychologic symptoms 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, coarse and thick skin, and sluggishness Blood tests to evaluate thyroid function *Features include symptoms and results of the doctor's examination. Features mentioned are typical but not always present.

Testing: Most causes of itching can be diagnosed without testing. If the diagnosis of a skin abnormality is not clear from its appearance and the person's history, removal (biopsy) of a skin sample may be necessary so that it can be analyzed. If the cause of itching seems to be an allergic reaction but the substance causing the allergic reaction is not evident, skin testing may be necessary. In skin testing, substances that can cause allergic reactions on contact are applied to the skin, either in a patch (called patch testing) or with a small needle (called prick testing).

If the cause seems not be an allergic reaction or skin disorder, testing is done based on the person's other symptoms. For example, tests may done for gallbladder or liver disorders, chronic kidney disease, thyroid disorders, diabetes, or cancer.

Treatment

Disorders that cause itching are treated. Sometimes other measures can also help relieve itching.

Skin care: Skin care measures can help relieve itching regardless of cause. Baths or showers should be short, no more frequent than necessary, and taken with cool or lukewarm (not hot) water. Using moisturizing soap and skin lubricants can also help, as can humidifying dry air (for example, in winter) and not wearing tight or wool clothing.

Topical treatments: Topical treatments can be applied to the skin if only a specific area is affected. To be effective, capsaicin cream should be used for at least 2 weeks. It tends to burn, but the burning decreases over time. Menthol and camphor creams have strong odors but can be used, as can tacrolimus or pimecrolimus creams.

Corticosteroid creams can help relieve itching and often clear up the rash and other skin abnormalities in disorders such as eczema, contact dermatitis, psoriasis, and lichen simplex chronicus. Corticosteroids should usually not be used when the skin is infected, when an infestation is present, when no rash or skin abnormalities are present, and when the cause is systemic.

Type B ultraviolet light can relieve itching but can cause sunburn-like effects and increases the risk of skin cancers.

Systemic treatments: Systemic treatments are drugs that are taken internally, usually by mouth. They are used if itching is widespread or if topical treatments are ineffective.

Antihistamines, particularly hydroxyzine, are used most often. Some antihistamines, such as cyproheptadine, diphenhydramine, and hydroxyzine, cause drowsiness. They help relieve itching and, when used before bedtime, aid in sleep. However, these drugs are usually not given during the day to elderly people, who are at higher risk of falling because of drowsiness. Cetirizine and loratadine cause less drowsiness but rarely can have this effect in older people. Fexofenadine causes less drowsiness but sometimes causes a headache. Doxepin makes people very drowsy and is effective, so it can be taken at bedtime if itching is severe.

Cholestyramine is used to treat itching caused by gallbladder or liver disorders, chronic kidney disease, or polycythemia vera. However, cholestyramine has an unpleasant taste, causes constipation, and can decrease absorption of other drugs. Naltrexone can be used to treat itching caused by gallbladder or liver disorders but may increase pain if pain is present. Gabapentin can help relieve itching caused by chronic kidney disease but can cause drowsiness.

Key Points

• Itching usually results from dry skin, a skin disorder, or an allergic reaction.
• If the person has no rash or skin abnormalities, the cause may be a drug, an allergic reaction that has internal effects, or a systemic disorder.
• Skin care measures (such as limiting bathing, moisturizing the skin, and humidifying the air) can usually help relieve itching.
• Itching can usually be relieved by topical or systemic treatments.

Last full review/revision December 2006 by Karen McKoy