Pruritus (itching) can be a symptom of primary skin diseases or of systemic disease. Skin diseases notorious for causing intense pruritus include scabies, pediculosis, insect bites, urticaria, atopic and contact dermatitis, lichen planus, miliaria, and dermatitis herpetiformis.

When pruritus is prominent without any identifiable skin lesions, dry skin (especially in elderly people), systemic disease, and drugs should be considered

Systemic diseases that cause generalized pruritus include

• Cholestatic diseases
• Uremia
• Polycythemia Vera
• Hematologic malignancies
• Hyper- and hypothyroidism
• Diabetes
• Iron deficiency
• Internal cancers
• Pruritus is rarely psychogenic

Drugs that cause generalized pruritus

• Barbiturates
• Salicylates 
• Morphine
• Cocaine

Evaluation

History:  Key elements of the history include drug exposures and an occupational/hobby history

Physical examination: Examination should focus on identification of an underlying skin disease. Identification of lesions may be complicated by redness, papules, excoriation, fissures, lichenification, and hyper pigmentation that all may be a result of persistent scratching

Testing: complete blood count, liver function test, renal function test, thyroid function test, and biopsy testing

Treatment

Any underlying cause is treated

Supportive treatment involves proper skin care and use of topical, systemic, and/or physical agents

Skin care

• Skin care involves use of cool or lukewarm (but not hot) water when bathing
• Limitations on use of soap, bathing duration, and bathing frequency
• Liberal use of emollients such as white petrolatum or other oil-based products
• Avoidance of irritating or tight clothing

 

Topical agents may help localized pruritus, includes camphor/menthol lotions or creams containing 0.125 to 0.25% menthol, corticosteroids, Diphenhydramine etc

Systemic agents are indicated for generalized pruritus or local pruritus resistant to topical agents. Antihistamines like Cetrizine, Loratidine, hydroxyzine, fexofenadine, cholestyramine

Physical agents that may be effective for pruritus include ultraviolet (UV) phototherapy, transcutaneous electrical nerve stimulation (TENS), and acupuncture.