What Causes Itchy Skin or Pruritus?

Causes of Chronic Itch

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Pruritus refers to an unpleasant sensation that causes the need to scratch, commonly called itching by most people. Itching may be localized to a certain area of the body, or can be all over, or generalized. When there is a rash that goes along with the pruritus, the cause is usually easily determined and treated. However, the most difficult cases of pruritus are those without an associated rash.

Learn more about the most common causes of allergic rashes that cause itching.

What Causes Itching?

Pruritus and pain are closely related sensations since the same nerves transmit both signals to the brain. When the area of skin is scratched, that same area may become even itchier, leading to more scratching. This is called the itch-scratch cycle. In general, pruritus can be related to a problem with the skin or another underlying disease of the body (systemic disease). When itching is localized to a particular area of skin, it usually is not caused by a systemic disease.

Localized Pruritus

Areas of itching that are only on one part of the body are more likely caused by a problem of the skin. The area of the body that itches may give a clue as to the cause of the itch.

Scalp. Common causes of itching of the scalp include psoriasis, head lice, seborrheic dermatitis (dandruff) and contact dermatitis.

Eyelids. Common causes of eyelid itching include contact dermatitis, atopic dermatitis, and allergic conjunctivitis.

Nose. The most common cause of nasal itching is allergic rhinitis.

Ears. Itching of the ear canal has been associated with allergic rhinitis, contact dermatitis and otitis externa (swimmer's ear).

Chest/Abdomen/Back. Common causes of itching of the skin on the main part of the body may include contact dermatitis, atopic dermatitis, scabies infection, psoriasis, and folliculitis.

Arms. Itching of the arms, especially the area at the bend of the elbow, can be due to atopic dermatitis. Other causes include xerosis (dry skin) and brachioradialis pruritus (itching along the upper arms, neck and shoulder blades related to sun exposure and nerve damage of the upper spine).

Legs. Itching of the legs is caused by many of the same diseases that cause itching of the arms, and atopic dermatitis is a very common cause of itching behind the knees. Pruritic rashes of the knees (and elbows) is commonly caused by psoriasis and dermatitis herpetiformis.

Hands and Feet. Itching of the hands and feet may be due to contact dermatitis, atopic dermatitis, pompholyx (dyshidrotic eczema), tinea (“ringworm”) and scabies.

Groin/Armpits. Common causes of itching of the groin and armpits include tinea (“jock itch”), contact dermatitis, scabies and candida (yeast) infections.

Anus. The most common cause of itching of the anus region is pruritus ani, caused by an intestinal infection by pinworms.

Generalized Pruritus

In those with generalized pruritus or itching all over, a systemic disease may be the cause in about 50 percent of people. Symptoms also may be caused by medication use, various infections (including parasitic infections of the intestines), iron deficiency, liver disease, kidney disease, high or low thyroid function, as well as certain cancers such as lymphoma.

Chronic urticaria (hives), especially dermatographism, and systemic forms of contact dermatitis are also common causes of generalized pruritus, even if no visible rash is present.

Medications that are well known to cause itching include opiates, such as Vicodin (acetaminophen/hydrocodone), morphine and codeine. Other groups of medications causing itching include Plaquenil (hydroxychloroquine), aspirin, NSAIDs, and any of a large number of medications that cause itching by affecting the liver.

Tests for generalized pruritus, especially when no rash is present, may include a complete blood count, kidney function, liver function, thyroid function, iron level, stool studies for parasites, and a chest x-ray (looking for evidence of lymphoma).

How is Itching Treated?

The best treatment of pruritus is to fix the underlying cause of the itching, as well as treatment of the specific skin condition. Non-specific treatments for pruritus, such as topical steroid creams and oral antihistamines, as well as good skin care and moisturizing, can provide much relief for people with generalized pruritus.

It is recommended that people with symptoms of itching, especially generalized pruritus, see their doctor for appropriate evaluation and treatment.

If this article has been useful, you may also like one or more of the following articles:


Puchner TC, Fink JN. A Case of Generalized Pruritus Without Rash. Ann Allergy Asthma Immunol. 2000;85:450-456.

Yosipovitch G, David M. The Diagnostic and Therapeutic Approach to Idiopathic Generalized Pruritus. International J of Dermatology. 1999;38:881-887.

Moses S. Pruritus. American Family Physician. 2003;68:1135-42.

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