Management of Scabies in Adults
Treat with permethrin 5% cream applied to all areas of the body from the neck down and washed off after 8-14 hours, or oral ivermectin 200 μg/kg taken with food and repeated in 2 weeks. 1, 2, 3
First-Line Treatment Options
Permethrin 5% cream is the preferred topical treatment for uncomplicated scabies in adults. 1, 2 Apply thoroughly to all skin surfaces from the neck down, ensuring coverage of all body folds and creases. 3 The cream should remain on the skin for 8-14 hours before washing off. 4, 1, 3 Usually 30 grams is sufficient for an average adult. 3 One application is generally curative. 3
Oral ivermectin 200 μg/kg is equally effective as first-line therapy. 1, 2 Take with food to increase bioavailability and penetration into the epidermis. 1, 2 A second dose must be administered after 2 weeks. 1, 2 No dosage adjustments are required for patients with renal impairment. 2
Alternative Treatment Options
If permethrin or ivermectin are unavailable or contraindicated:
- Lindane 1% (1 oz lotion or 30g cream) applied thinly from neck down and washed off after 8 hours. 4 However, lindane resistance has been reported in some areas of the United States. 4
- Sulfur 6% ointment applied nightly for 3 consecutive nights, washing off previous applications before reapplying, then thoroughly washing off 24 hours after the last application. 4, 1
- Crotamiton 10% applied to entire body from neck down nightly for 2 consecutive nights, washed off 24 hours after the second application. 4, 5
Critical Application Details
Apply topical treatments to specific high-risk areas: finger webs, wrists, axillary folds, abdomen, buttocks, inframammary folds, and in men, the genitalia. 6
For elderly patients or those with atypical presentations, consider scalp-to-toes application rather than neck-down only, as head involvement can occur in geriatric patients. 1, 7 The hairline, neck, temple, and forehead may be infested in these populations. 3, 7
Trim fingernails short and apply medication under nails, as scabies mites are likely to remain there. 1, 5
Crusted (Norwegian) Scabies
Immunocompromised patients require aggressive combination therapy: 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. 1, 2
Environmental Management
Decontaminate all bedding and clothing by machine washing and drying using the hot cycle, dry cleaning, or removing from body contact for at least 72 hours. 4, 1, 2 Fumigation of living areas is unnecessary. 4, 1, 2
Contact Management
Examine and treat ALL sexual, close personal, and household contacts within the preceding month simultaneously, even if asymptomatic. 4, 1, 2 Failure to treat contacts simultaneously is a major cause of treatment failure and reinfection. 1, 2
Follow-Up and Expected Course
Pruritus may persist for up to 2 weeks after successful treatment and is rarely a sign of treatment failure. 4, 1, 2, 3 This is not an indication for retreatment. 3
Consider retreatment only if: symptoms persist beyond 2 weeks, live mites are observed after 14 days, or other signs of treatment failure are present. 4, 1, 2, 3
Critical Pitfalls to Avoid
- Never use lindane after bathing or in patients with extensive dermatitis (increased absorption and seizure risk). 4, 1, 2
- Never use lindane in pregnant or lactating women, or children under 10 years due to neurotoxicity risk. 4, 1, 2
- Do not forget the second dose of ivermectin at 2 weeks - this is essential for eradication. 1, 2
- Inadequate application of topical treatments (missing body folds, under nails) leads to treatment failure. 1, 2
- Treating the patient without treating contacts guarantees reinfection. 1, 2