What is the recommended treatment for scabies in an otherwise healthy individual?

Treatment for Scabies

First-Line Treatment Recommendation

Permethrin 5% cream applied from the neck down (or scalp-to-toes in infants, elderly, and immunocompromised patients) and washed off after 8-14 hours is the preferred first-line treatment for scabies in otherwise healthy individuals. 1, 2, 3, 4

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Primary Treatment Options

Permethrin 5% Cream (Preferred)

• Apply to all body areas from neck down and wash off after 8-14 hours 1, 4
• One application is generally curative in uncomplicated cases 4
• Approximately 30 grams is sufficient for an average adult 4
• More effective, safer, and less expensive than ivermectin for standard scabies 1
• Cure rate of 96.9% with two applications one week apart 5

Special application considerations:

• Infants, elderly, and immunocompromised patients require scalp-to-toes application including hairline, neck, temple, and forehead 1, 4, 6
• Apply under fingernails after trimming them short 7, 8
• The scalp is rarely infested in healthy adults but commonly affected in vulnerable populations 4, 6

Oral Ivermectin (Alternative First-Line)

• Dosage: 200 μg/kg body weight, repeated in 2 weeks 1, 2, 3
• Must be taken with food to increase bioavailability and epidermal penetration 1, 3
• Single dose provides 62.4% cure rate; two doses at 2-week interval increases efficacy to 92.8% 5
• The second dose is essential because ivermectin has limited ovicidal activity and does not kill eggs present at initial treatment 1, 3
• No dosage adjustments needed for renal impairment, but safety uncertain in severe liver disease 1

Preferred situations for ivermectin:

• Crusted (Norwegian) scabies 1, 3, 9
• Immunocompromised patients 2, 9
• Institutional outbreaks 2, 8
• Bedridden patients 8

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Alternative Treatment Options (When First-Line Fails or Unavailable)

Lindane 1% (Use Only as Last Resort)

• Apply thin layer from neck down, wash off after 8 hours 1, 2
• Should only be used if patient cannot tolerate recommended therapies or these have failed 1
• Contraindicated in: children <10 years, pregnant/lactating women, persons with extensive dermatitis 1, 2, 3
• Never apply after bathing as this increases absorption and seizure risk 1, 2, 3
• Risk of neurotoxicity, seizures, and aplastic anemia 1, 3
• Resistance reported in some U.S. regions 1

Other Alternatives

• Sulfur 6% ointment: Apply nightly for 3 nights, washing off previous applications before reapplying 2
• Crotamiton 10%: Apply nightly for 2 consecutive nights, wash off 24 hours after second application 2, 7
• Benzyl benzoate 25%: 87% cure rate but causes burning sensation in 43% of patients; used internationally when permethrin unavailable 2, 10

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Special Populations

Pregnant and Lactating Women

• Permethrin 5% cream is the preferred treatment 1, 2, 3, 10
• Ivermectin classified as "human data suggest low risk" in pregnancy and probably compatible with breastfeeding 1
• Avoid lindane due to association with neural tube defects, mental retardation, and accumulation in placenta/breast milk 1

Infants and Young Children

• Permethrin is recommended 1, 2, 3
• Must include scalp, temple, and forehead in application 1, 4
• Never use lindane in children <10 years due to neurotoxicity risk 1, 2, 3

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Crusted (Norwegian) Scabies

Requires aggressive combination therapy due to massive mite burden (thousands to millions of mites) 2, 3:

• Permethrin 5% cream applied daily for 7 days, then twice weekly until cure 2, 3
• PLUS oral ivermectin 200 μg/kg on days 1,2,8,9, and 15 2, 3
• The multiple-dose ivermectin schedule addresses limited ovicidal activity and massive mite burden 3
• Single-application permethrin or single-dose ivermectin will fail 3
• Most common in immunodeficient, debilitated, or malnourished persons 3

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Environmental and Contact Management

Decontamination (Critical to Prevent Reinfection)

• Machine wash and dry bedding/clothing using hot cycle, dry clean, or remove from body contact for at least 72 hours 1, 2, 3, 10
• Vacuum furniture and carpets 8
• Isolate non-launderable items for minimum 2 days (or 3 weeks for rigorous approach) 8
• Fumigation of living areas is unnecessary 1, 2, 3
• Keep fingernails closely trimmed to reduce injury from scratching 1, 2

Contact Treatment

• Examine and treat all persons with sexual, close personal, or household contact within the preceding month 1, 2, 3, 10
• All contacts must be treated simultaneously to prevent reinfection 1, 8
• For institutional outbreaks, treat entire at-risk population and consult expert 2
• Avoid sexual contact until patients and partners treated, bedding decontaminated, and reevaluation completed 1

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Follow-Up and Retreatment

Expected Post-Treatment Course

• Pruritus may persist for up to 2 weeks after successful treatment and is rarely a sign of treatment failure 2, 3, 10, 4
• This persistent itching represents sensitization reaction, not active infestation 1, 4
• Persistent pruritus alone is NOT an indication for retreatment 4

Retreatment Criteria

• Retreatment indicated if live mites observed after 14 days 4
• Evaluate after 1 week if symptoms persist 1, 3
• Consider retreatment after 2 weeks if: symptoms persist beyond 2 weeks, live mites observed, or other signs of treatment failure present 2, 3
• If no response to one regimen, switch to alternative regimen 1

Common Reasons for Treatment Failure

• Failure to treat all close contacts simultaneously 2, 3
• Inadequate application of topical treatments (missing body areas, especially scalp in vulnerable populations) 2, 3, 8
• Not repeating ivermectin dose after 2 weeks 2, 3
• Reinfection from untreated contacts or fomites 2, 3, 8
• Medication resistance 1, 8
• Application errors (failure to treat face/scalp, failure to reapply medication) 8

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Critical Pitfalls to Avoid

• Do not use lindane after bathing or showering (increases absorption and seizure risk) 1, 2, 3
• Do not use lindane in contraindicated populations (children <10 years, pregnant/lactating women, extensive dermatitis) 1, 2, 3
• Do not skip scalp/face application in infants, elderly, or immunocompromised patients 1, 4, 6
• Do not forget the second ivermectin dose at 2 weeks 1, 2, 3
• Do not retreat based solely on persistent itching within 2 weeks 2, 3, 10, 4
• Do not fail to treat all household and close contacts simultaneously 1, 2, 3, 8

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Secondary Bacterial Infection

• Staphylococcus aureus is the most common secondary bacterial pathogen in impetiginized scabies 11
• Streptococcus pyogenes also commonly causes secondary infection 11
• Combination of permethrin 5% and fusidic acid 2% cream is more effective than permethrin alone for impetiginized scabies (95% vs 35% efficacy at day 14) 11