What Is Pruritus?

"Pruritus" is the clinical name for the symptom of itching. There are many causes of pruritus. They include dry skin (xerosis) and skin conditions such as eczema (an inflammatory skin disease also called atopic dermatitis), allergic skin reactions (contact dermatitis), and systemic conditions, such as diabetes and blood cancers.

This article will discuss what causes pruritus, symptoms, diagnosis, treatment, and prevention.

Pruritus Causes

There are many causes of pruritus. A common cause of pruritus is xerosis, especially in older adults and in people who live in colder climates. Other causes include:

• Skin conditions such as eczema and psoriasis (an autoimmune skin disorder)
• Allergic contact dermatitis from exposure to nickel, poison ivy, latex, laundry detergents/soaps, and other irritants
• Viral infections such as human immunodeficiency virus (HIV), herpes zoster (shingles), viral hepatitis
• Bacterial infections such as folliculitis (infection of the hair follicles)
• Parasitic infestation such as scabies
• Insect bites
• Diabetes
• Blood cell cancer and other blood disorders, such as Hodgkin's lymphoma (a cancer of the lymphatic system) and polycythemia vera (a blood disorder with overproduction of red blood cells)
• Systemic conditions such as urticaria (hives), hyperthyroidism (overactive thyroid), iron deficiency anemia, uremia (high levels of waste products in the blood, seen in kidney failure), and cholestasis (impaired bile flow)
• Medications such as opioids, antimalarial drugs
• Allergic food triggers, including reactions to shellfish, nuts, and nitrates
• Heat exposure 
• Pregnancy
• Neurological causes such as notalgia paresthetica (a sensory disorder causing an itch below the left shoulder blade)

Pruritus can occur as a localized or systemic symptom based on the underlying cause. The underlying mechanism of your pruritus depends on the precipitating cause, and no single mechanism explains all forms of pruritus.

In allergic reactions, the chemical histamine is released by mast cells and triggers itchiness. But in nonallergic causes of pruritus, it may be due to other chemicals. For example, serotonin appears to be a key component of pruritus in systemic conditions such as polycythemia vera, uremia, cholestasis, and lymphoma.

Pruritus Symptoms

Pruritus is a symptom in and of itself and may be accompanied by other symptoms, including:

• Warmth
• Swelling (angioedema) around the affected area
• Fever
• Redness
• Bumps, spots, or blisters
• Dry or cracked skin
• Leathery or scaly skin
• Fatigue (sometimes due to difficulty sleeping)

Your accompanying symptoms are largely dependent on the underlying conditions that are causing your pruritus. 

Risk Factors 

Some of the groups at higher risk of developing pruritus include: 

• Older adults
• People with asthma, eczema, or seasonal allergies 
• People with diabetes
• People who are immunocompromised (have a weakened immune system)
• Pregnant people
• People with end-stage kidney disease
• People with certain cancers

Diagnosis

A thorough history and a complete physical examination must be performed to determine the underlying cause of your pruritus. A proper diagnosis is key, as treating the underlying condition is the most effective treatment for pruritus.

Some questions you might be asked by a healthcare provider include:

• How long have you experienced this itch?
• Have you had recent contact with or exposure to a new, toxic, foreign, or unknown substance?
• Describe your symptoms. Have you experienced these symptoms in the past?
• Do other members of your household exhibit the same symptoms?
• Does your itching wake you up at night?
• Do you have any underlying medical conditions?
• Do you have allergies? 
• What medications are you currently taking?

A careful skin exam will be performed to look at the characteristics of any skin rash or lesions and signs of infection or allergic reaction. Suspicious skin lesions may be biopsied (a sample of skin is removed to be examined under a microscope).

If your symptoms do not resolve after two weeks of treatment your symptoms, your healthcare provider may order a series of labs and refer you to a specialist to determine the cause of your pruritus symptoms. 

Treatment

When you're trying to pacify a nagging itch, using a moisturizer (preferably one approved by a healthcare provider), calamine lotion, or even a cool compress can be incredibly soothing. Some lifestyle modifications like wearing loose, light clothing and using unscented aloe-based lotions may also be helpful.

But these anti-itch methods usually only provide temporary relief. Treating the underlying condition at the root of your pruritus is the most definitive way to get rid of your itch.

If your itch is due to an allergic reaction, using an antihistamine is a mainstay treatment that has proven to be effective. For local pruritus, a corticosteroid cream might help.

If you have systemic pruritus from conditions such as polycythemia vera, uremia, cholestasis, and lymphoma, serotonin inhibitors such as Periactin (cyproheptadine), Paxil (paroxetine), and Zofran (ondansetron) are proven anti-itch treatments.

Phototherapy uses natural or artificial light to treat itchy skin conditions, including eczema and psoriasis.

Prevention

Sometimes pruritus is simply unavoidable, especially if the cause of your itch is due to a systemic condition, meaning one that affects your entire body. Fortunately, most cases of pruritus are benign (noncancerous), localized (staying in a single spot), and can be prevented. The following tip may help you prevent pruritus:

• Avoid foreign substances that trigger your pruritus.
• Shower in lukewarm water. 
• Moisturize your skin after showering (preferably daily).
• Use mild bath soaps that won’t irritate the skin.
• Reduce stress and anxiety whenever possible and as much as you can. 
• Try over-the-counter (OTC) oral allergy medicine like antihistamines (remember to consult a healthcare professional before you do so).  
• Use a humidifier.
• Use creams, lotions, or gels that soothe and cool your skin (preferably unscented).
• Avoid scratching.
• Use sunscreen regularly. 
• Wear loose clothing.

Summary

Pruritus, known simply as itching, can be caused by many conditions ranging from dry skin (xerosis) and infections to dermatologic skin conditions such as eczema (atopic dermatitis), infections, allergic reactions, and systemic conditions such as diabetes. 

A Word From Verywell

Localized itching is usually benign and can be well managed with the use of lotions. Oftentimes, these mild cases resolve on their own without the need for any treatment at all.

Still, widespread pruritus that lasts for more than a few days should not be ignored. Itching that occurs all over your body may be a sign of an underlying condition. If you experience itching that does not resolve with symptomatic treatment within two weeks, check in with your healthcare provider,