What is the recommended treatment for a scabies rash?

Scabies Treatment

Permethrin 5% cream applied to all areas of the body from the neck down and washed off after 8-14 hours is the first-line treatment for scabies, with oral ivermectin 200 μg/kg (repeated in 2 weeks) as an equally effective first-line alternative. 1, 2, 3

First-Line Treatment Options

Topical Permethrin 5% Cream

• Apply to entire body surface from neck down and wash off after 8-14 hours 1, 4
• Infants and young children require application to scalp, temple, and forehead as well, since scabies commonly infests these areas in this age group 4
• One application is generally curative 4
• Permethrin is the preferred agent for pregnant/lactating women and children under 10 years 1, 2, 3
• Use approximately 30 grams for an average adult 4
• More effective when applied as cold cream (stored in refrigerator) for two consecutive days rather than single application, with cure rates of 87.2% vs 61.8% 5

Oral Ivermectin

• Dose: 200 μg/kg body weight, repeated after 2 weeks 1, 2, 3
• Must be taken with food to increase bioavailability and epidermal penetration 1, 3
• The second dose at 2 weeks is essential because ivermectin has limited ovicidal activity 1
• No dosage adjustment needed for renal impairment 1, 3
• Safety of multiple doses in severe liver disease is unknown 1
• Particularly useful for institutional outbreaks, immunocompromised patients, and crusted scabies 6

Alternative Treatment Options (When First-Line Fails or Cannot Be Used)

Lindane 1%

• Apply thinly from neck down and wash off after 8 hours 1, 2, 3
• Should only be used if recommended therapies fail or cannot be tolerated 1
• Absolute contraindications: children <10 years, pregnant/lactating women, persons with extensive dermatitis 1, 2, 3
• Never apply after bathing or showering due to increased absorption and seizure risk 1, 2, 3
• Resistance reported in some U.S. regions 1

Sulfur 6% Ointment

• Apply nightly for 3 consecutive nights 1, 2
• Wash off previous application before reapplying 1, 2
• Thoroughly wash off 24 hours after final application 1

Special Population Management

Crusted (Norwegian) Scabies

• Requires combination therapy: 2, 3
  • Permethrin 5% cream applied daily for 7 days, then twice weekly until cure
  • PLUS oral ivermectin 200 μg/kg on days 1,2,8,9, and 15
• This aggressive regimen is necessary due to massive mite burden 2, 3

Immunocompromised Patients

• Higher risk for crusted scabies and treatment failure 2, 3
• Consider combination therapy even for non-crusted presentations 6

Environmental and Contact Management

Decontamination Requirements

• Machine wash and dry bedding/clothing using hot cycle, OR dry clean, OR remove from body contact for at least 72 hours 1, 2, 3
• Fumigation of living areas is unnecessary 1, 2, 3
• Keep fingernails closely trimmed to reduce injury from scratching 2, 3

Contact Tracing and Treatment

• Examine and treat all persons with sexual, close personal, or household contact within the preceding month 1, 2, 3
• All contacts must be treated simultaneously to prevent reinfection 2, 3
• For institutional outbreaks, treat the entire at-risk population 2

Follow-Up and Management of Persistent Symptoms

Expected Post-Treatment Course

• Pruritus may persist for up to 2 weeks after successful treatment 2, 3
• Approximately 75% of patients with pruritus at 2 weeks will have resolution by 4 weeks 4
• Persistent itching is rarely a sign of treatment failure 4

Indications for Retreatment

• Demonstrable living mites after 14 days 4
• Symptoms persisting beyond 2 weeks with clinical evidence of active infestation 2, 3
• New lesions appearing after initial improvement 2, 3

Common Causes of Treatment Failure

• Failure to treat all close contacts simultaneously 2, 3
• Inadequate application of topical treatments 2, 3
• Reinfection from untreated contacts or contaminated fomites 2, 3
• Not repeating ivermectin dose after 2 weeks 2, 3
• Medication resistance (particularly with lindane) 1

Critical Pitfalls to Avoid

• Do not use lindane after bathing - increases absorption and seizure risk 1, 2, 3
• Do not use lindane in children <10 years, pregnant/lactating women, or persons with extensive dermatitis - risk of neurotoxicity 1, 2, 3
• Do not expect immediate symptom resolution - pruritus commonly persists 1-2 weeks post-treatment 2, 3, 4
• Do not forget the second ivermectin dose at 2 weeks - essential for eradicating eggs 1, 2, 3
• Do not treat the patient without simultaneously treating all household and close contacts - leads to reinfection 2, 3
• Do not apply permethrin to eyes - flush immediately with water if contact occurs 4