II. Causes: Dermatologic Conditions
- Dry Skin or Xerosis (most common cause)
- Atopic Dermatitis
- Allergic Contact Dermatitis
- Bullous Pemphigoid
- Dermatitis Herpetiformis
- Superficial Folliculitis
- Psoriasis
- Lichen Planus
- Chronic Urticaria
-
Cutaneous T-Cell Lymphoma (Mycosis Fungoides)
- Pruritus suggests worse prognosis
- Sunburn
- Local Infection or bites
- Dermatophyte Infection (e.g. Tinea Corporis, Tinea Capitis, Tinea Pedis)
- Scabies
- Pediculosis corporis (lice)
- Bed Bugs
- Other Insect Bites (e.g. Mosquitoes, fire ants, gnats, fleas, Chiggers)
- Complications of excessive scratching
III. Causes: Systemic
- Autoimmune Causes
- Dermatitis Herpetiformis
- Dermatomyostitis
- Linear Immunoglobulin A Disease
- Sjogren Syndrome
- Scleroderma
- Hematologic Causes
- Hemochromatosis
- Iron Deficiency Anemia
- Mastocytosis
- Monoclonal Gammopathy (Plasma Cell Disorder)
- Polycythemia Rubra Vera (Pruritus in 30-50% of cases)
- Provoked by hot shower or bath
- Pricking type itch may persist for hours
- Malignancy
- Leukemia
- Multiple Myeloma
- Hodgkin's Lymphoma
- Malignant Carcinoid
- Paraneoplastic Syndrome (solid malignancy)
- Hepatobiliary Disease
- Biliary Cirrhosis
- Cholestasis (bile salt protease release in skin)
- Hepatitis (esp. Hepatitis C)
- Sclerosing Cholangitis
- Biliary duct obstruction
- Endocrine Conditions
- Carcinoid Syndrome
- Hyperthyroidism (4-11% long-standing Grave's Disease)
- Hyperparathyroidism
- Diabetic Neuropathy
- Neurologic Causes
- Systemic infection
- HIV Infection (see Pruritus in HIV)
- Parvovirus B19
- Parasitic Infections
- Filariasis
- Schistosomiasis
- Onchocerciasis (river blindness)
- Ascariasis
- Hookworm
- Trichinosis
- Miscellaneous Causes
- See Pruritus in Pregnancy
- See Exposures below (includes medications, pregnancy)
- Severe Chronic Renal Failure (Uremic Pruritus)
- Neurodermatitis or Delusions of Parasitosis
- Rapid weight loss (e.g. Anorexia Nervosa)
- Chronic Urticaria
IV. Causes: Localized
- Eye
- Ear
- Scalp
- Back
- Notalgia Paresthetica
- Xerotic Eczema
- Psoriasis
- Folliculitis
- Cholestasis (Butterfly rash)
- Arm
- Brachioradial Pruritus
- Xerotic Eczema
- Eczematous Dermatitis (antecubital fossa)
- Hands
- Dyshidrotic Eczema
- Eczematous Dermatitis
- Contact Dermatitis
- Scabies (interdigital web space involvement)
- Groin or inguinal area
- See Pruritus Vulvae
- Candidiasis
- Tinea Cruris
- Erythrasma
- Contact Dermatitis
- Extramammary Paget's Disease
- Intertrigo
- Lichen Sclerosis et Atrophicus (LS&A)
- Pediculosis
- Scabies
-
Rectum
- Pruritus Ani
- Anal Fissure
- Condylomata acuminata
- Pinworm
- Legs
- Xerotic Eczema (shin)
- Neurodermatitis
- Stasis Dermatitis
- Atopic Dermatitis (popliteal fossa)
- Lichen Simplex (lateral malleolus)
- Dermatitis Herpetiformis (knee)
- Cutaneous T-Cell Lymphoma (buttocks and thighs)
- Feet
- Tinea Pedis
- Eczematous Dermatitis
- Contact Dermatitis
- Scabies (interdigital web space involvement)
V. Causes: Exposure-Related Pruritus
- Water
- Aquagenic Pruritus
- Intense distressing itch after water contact
- CholinergicUrticaria
- Polycythemia Vera (follows warm bath)
- Swimmer's Itch
- Aquagenic Pruritus
- Pregnancy (See Pruritus in Pregnancy)
- Medications
- Allergen or irritant exposure (e.g. Contact Dermatitis)
- See Allergic Contact Dermatitis
- See Occupational Contact Dermatitis
- See Irritant Contact Dermatitis
- Heat exposure: Miliaria Rubra (Prickly Heat)
- Cat exposure
- Fiberglass exposure (Fiberglass Dermatitis)