Pruritus

Background

Normal dermal anatomy.

• Pruritus (itchiness) is a common ED complaint that may represent a benign dermatologic condition or a systemic disease
• Can be localized or generalized
• Generalized pruritus without rash warrants consideration of systemic causes (renal, hepatic, hematologic, endocrine, malignancy)
• Most common ED presentations are allergic/contact dermatitis, urticaria, drug reactions, and infestations

Clinical Features

History

• Onset, duration, distribution (localized vs. generalized)
• Relationship to exposures: new medications, soaps, detergents, plants, animals, occupational
• Timing: worse at night (scabies, eczema), seasonal (allergic)
• Associated rash: urticarial, vesicular, papular, or no visible skin changes
• Constitutional symptoms: weight loss, night sweats, fatigue (consider malignancy, systemic disease)
• Medical history: liver disease, kidney disease, thyroid disease, diabetes, HIV, lymphoma

Physical Exam

• Excoriations, lichenification (chronic scratching)
• Primary lesion identification: wheals (urticaria), vesicles (contact dermatitis), burrows (scabies), dermatomes (varicella-zoster)
• Distribution pattern may suggest etiology
• Jaundice, hepatomegaly (cholestasis)
• Lymphadenopathy (lymphoma)
• Thyromegaly (hyperthyroidism)

Red Flags

• Generalized pruritus without rash (consider systemic cause)
• Associated with urticaria + dyspnea/hypotension → anaphylaxis
• Unintentional weight loss (malignancy screen)
• Jaundice (biliary obstruction)
• Nighttime pruritus with household contacts affected (scabies)

Differential Diagnosis

Pruritus

Dermatologic/Immunologic Disorders

• Xerosis
• Atopic dermatitis
• Allergic reaction
  • Contact dermatitis
  • Poison Oak, Ivy, Sumac dermatitis
  • Allergic conjunctivitis
• Bullous pemphigoid
• Exfoliative erythroderma
• Miliaria (Heat Rash)
• Lichen sclerosus
• Blister chemical agents

Infection, Infection-associated, and Other Critters

• Varicella
• Pityriasis rosea, Erythema infectiosum
• Pruritic papular eruption of HIV
• Candida vulvovaginitis, Candida dermatitis
• Tinea
• Cercarial dermatitis
• Scabies, Lice, Bed bugs
• Herpes simplex
• Condyloma acuminata
• Strongyloides stercoralis, Enterobius, Fasciola hepatica, Loa loa, Dracunculiasis
  • Hymenoptera stings

Systemic Conditions

• Uremia
• Hyperbilirubinemia/cholestasis
• Hepatitis C
• Leukemia, Lymphoma
• Polycythemia vera
• Medication or drug of abuse adverse effect
• Psychiatric/psychogenic

Dermatologic (With Rash)

• Urticaria / allergic reaction
• Contact dermatitis
• Atopic dermatitis (eczema)
• Scabies, pediculosis (lice)
• Varicella-zoster / herpes simplex
• Drug eruptions
• Fungal infections (Tinea, candidiasis)
• Psoriasis

Systemic (Without Primary Rash)

• Chronic kidney disease (uremic pruritus)
• Cholestasis / liver disease
• Hyperthyroidism or hypothyroidism
• Iron deficiency anemia, polycythemia vera
• Lymphoma (Hodgkin's), other malignancy
• HIV
• Pregnancy (intrahepatic cholestasis of pregnancy)

Evaluation

Localized Pruritus with Obvious Dermatologic Cause

• Clinical diagnosis usually sufficient
• No laboratory workup necessary

Generalized Pruritus Without Clear Cause

• CBC with differential (eosinophilia, polycythemia, anemia)
• BMP (renal function — uremia)
• Liver function tests, bilirubin (cholestasis)
• TSH (thyroid disease)
• Glucose (diabetes)
• Consider CXR if concern for lymphoma (mediastinal mass)
• Consider iron studies, HIV testing, hepatitis serologies based on clinical context

Management

General

• Treat underlying condition when identified
• Avoid hot water, harsh soaps, known irritants
• Emollients for dry skin

Symptomatic Relief

• Antihistamines: diphenhydramine, hydroxyzine, or non-sedating (cetirizine, loratadine)
• Topical steroids: for localized inflammatory dermatoses (avoid on face/groin long-term)
• Calamine lotion or cool compresses for temporary relief
• Oatmeal baths for generalized pruritus

Condition-Specific

• Urticaria: H1 blocker (diphenhydramine or cetirizine); add H2 blocker (famotidine) for refractory; short course prednisone for severe
• Scabies: permethrin 5% cream (applied neck down, left on 8-14 hours); treat all household contacts simultaneously
• Contact dermatitis: remove exposure, topical steroids, oral steroids for severe/widespread
• Uremic pruritus: nephrology consultation, gabapentin may help
• Cholestatic pruritus: cholestyramine, refer for biliary evaluation

Disposition

Discharge (Most Patients)

• Most patients with pruritus can be safely discharged
• Outpatient follow-up with primary care or dermatology for persistent or unexplained pruritus
• Return precautions: spreading rash, difficulty breathing, swelling, fever, worsening symptoms

Admit

• Associated anaphylaxis
• Severe drug reaction (consider Stevens-Johnson syndrome, DRESS syndrome)
• Symptomatic systemic disease requiring inpatient workup (new renal failure, obstructive jaundice)

See Also

• Rash
• Urticaria
• Allergic reaction
• Anaphylaxis
• Scabies
• Contact dermatitis