What is the recommended treatment for a typical case of scabies?

Scabies Treatment

First-Line Treatment Recommendation

Permethrin 5% cream is the preferred first-line treatment for typical scabies, applied from the neck down to all body areas and washed off after 8-14 hours, with a second application recommended 1 week later. 1, 2

Treatment Algorithm

Standard Adult Treatment

• Apply permethrin 5% cream to the entire body from the neck down, including all skin folds, creases, under fingernails, and between fingers and toes 1, 2
• Leave the cream on for 8-14 hours (typically overnight), then wash off thoroughly 1, 2
• Repeat the application exactly 1 week later to kill newly hatched mites, as permethrin has limited ovicidal activity 1
• Permethrin is more effective, safer, and less expensive than ivermectin for standard scabies 1

Alternative: Oral Ivermectin

• Ivermectin 200 μg/kg orally is an acceptable first-line alternative, particularly useful for patients who cannot apply topical treatments properly or in institutional outbreaks 1, 2, 3
• Must be taken with food to increase bioavailability and epidermal penetration 1, 3
• The second dose at 2 weeks is mandatory, not optional—ivermectin has limited ovicidal activity and does not kill eggs present at initial treatment 1, 3
• For a 56-kg patient, this equals four 3-mg tablets (12 mg total) as a single dose, repeated in 14 days 3

Special Population Modifications

Infants and Young Children

• Use permethrin 5% cream as first-line treatment 1, 2
• Apply scalp-to-toes, including hairline, neck, temple, and forehead—not just neck down as in adults 1
• Avoid ivermectin in children <10 years or weighing <15 kg due to potential neurotoxicity from blood-brain barrier penetration 3
• Permethrin is safe in infants ≥2 months of age 4

Pregnant and Lactating Women

• Permethrin 5% cream is the preferred treatment 1, 2
• Ivermectin is classified as "human data suggest low risk" in pregnancy and probably compatible with breastfeeding, but permethrin remains preferred 1, 3

Elderly and Immunocompromised Patients

• Apply permethrin scalp-to-toes, including hairline, neck, temple, and forehead 1
• Monitor more closely for treatment failure, as immunocompromised patients are at higher risk for crusted scabies 2

Critical Management Steps

Contact Treatment (Essential to Prevent Reinfection)

• Treat all household members, sexual partners, and close personal contacts simultaneously, even if asymptomatic 1, 2
• All contacts within the preceding month must be treated 1, 2
• Failure to treat contacts simultaneously is the most common cause of treatment failure 1

Environmental Decontamination

• Machine wash and dry all bedding, clothing, and towels using hot cycle 1, 2
• Alternatively, dry clean items or remove from body contact for at least 72 hours (mites cannot survive off the body beyond this period) 1, 2
• Fumigation of living areas is unnecessary 1, 2
• Vacuum furniture and carpets 5

Application Technique (Critical for Success)

• Apply to completely dry skin—do not apply immediately after bathing, as this increases absorption and potential toxicity 1
• Trim fingernails short and apply medication under nails using a toothbrush or similar applicator 1, 6
• Ensure complete coverage of all skin folds, between toes and fingers, umbilicus, and genital area 1

Follow-Up and Retreatment Criteria

Expected Post-Treatment Course

• Pruritus and rash may persist for up to 2 weeks after successful treatment due to allergic/sensitization reaction to dead mites 1, 2, 3
• Persistent itching alone is NOT an indication for retreatment 1
• Treat symptomatic pruritus with topical corticosteroids and oral antihistamines 3

When to Retreat

• Consider retreatment if symptoms persist beyond 2 weeks AND live mites are observed 1, 2
• Evaluate at 1-2 weeks if symptoms are severe or worsening 2
• New burrows or lesions appearing after 2 weeks suggest treatment failure or reinfection 1

Common Reasons for Treatment Failure

• Inadequate application of topical treatment (most common)—missing areas like scalp, face, or under nails 1, 5
• Failure to treat all close contacts simultaneously 1, 5
• Reinfection from untreated contacts or inadequately decontaminated fomites 1, 5
• Not repeating the second application/dose as directed 1, 3
• Medication resistance (rare but emerging concern) 1

Alternative Treatments (When First-Line Options Unavailable)

Second-Line Topical Agents

• Lindane 1%: Apply thinly from neck down, wash off after 8 hours 1

  • Contraindicated in children <10 years, pregnant/lactating women, and persons with extensive dermatitis due to neurotoxicity risk (seizures, aplastic anemia) 1, 2, 3
  • Never use after bathing, as this increases absorption and seizure risk 1

• Sulfur 6% ointment: Apply nightly for 3 consecutive nights 1

  • Safe in pregnancy and young infants when other options are contraindicated 1

• Crotamiton 10%: Apply nightly for 2 consecutive nights, wash off 24 hours after second application 1, 6

  • Less effective than permethrin but may be useful when other options fail 1

• Benzyl benzoate 25%: 87% cure rate but causes burning sensation in 43% of patients 1

Crusted (Norwegian) Scabies

This severe form requires aggressive combination therapy and specialist consultation 1, 2:

• Permethrin 5% cream applied daily for 7 days, then twice weekly until cure 1, 2
• PLUS oral ivermectin 200 μg/kg on days 1,2,8,9, and 15 1, 2, 3
• Single-application permethrin or single-dose ivermectin will fail in crusted scabies 2
• Occurs in immunocompromised, debilitated, or malnourished patients 2
• Far more contagious than typical scabies, with thousands to millions of mites present 2

Key Pitfalls to Avoid

• Not treating the scalp and face in infants, elderly, and immunocompromised patients 1
• Forgetting the second application/dose—this is mandatory, not optional 1, 3
• Using lindane in contraindicated populations (children, pregnancy, extensive dermatitis) 1, 2
• Applying permethrin immediately after a hot bath—increases systemic absorption 1
• Not taking ivermectin with food—significantly reduces efficacy 1, 3
• Retreating based on persistent itching alone before 2 weeks—this represents normal post-treatment reaction 1, 2
• Treating the patient but not household contacts—guarantees reinfection 1, 5