What is the recommended dosage of permethrin (or alternative treatments like ivermectin) for a female patient weighing 211lbs with scabies?

Scabies Treatment Dosing for 211 lb Female

For a 211 lb (96 kg) female patient with scabies, use permethrin 5% cream applied to the entire body from neck to soles of feet for 8-14 hours, OR oral ivermectin 19.2 mg (200 μg/kg) taken with food and repeated in 2 weeks. 1, 2

First-Line Treatment Options

Permethrin 5% Cream (Preferred)

• Apply approximately 30 grams to the entire body from neck down to soles of feet 2
• Massage thoroughly into skin, including between fingers/toes, under nails, wrists, elbows, armpits, genitals, and buttocks 3
• Leave on for 8-14 hours, then wash off completely with soap and water 1, 2
• One application is generally curative 2
• Permethrin is effective, safe, and less expensive than ivermectin 1

Oral Ivermectin (Alternative First-Line)

• Dose: 200 μg/kg = approximately 19.2 mg for 96 kg patient 1
• Must repeat the dose in exactly 2 weeks (ivermectin has limited ovicidal activity and doesn't kill eggs) 1
• Take with food to increase bioavailability and epidermal penetration 1, 4
• No dosage adjustment needed for renal impairment 1

Critical Application Details for Permethrin

Ensure skin is completely dry before application 3

• Apply to often-missed areas: hairline/neck/temple/forehead (especially if elderly), between all digits, under all nails, wrists, elbows, axillae, genitals, buttocks 3, 2
• Do not skip any body surface area from neck down 3

Expected Timeline and Follow-Up

Itching will persist for up to 2 weeks after successful treatment—this is NOT treatment failure 1, 3, 4, 5

• This represents an allergic reaction to dead mites, not ongoing infestation 3
• Only retreat if living mites are visible after 14 days 3, 2
• If symptoms persist beyond 2 weeks with evidence of active infestation, consider retreatment 1, 4, 5

Mandatory Contact and Environmental Management

All household members and sexual partners from the past month MUST be treated simultaneously, even if asymptomatic 3, 4, 5

• This is non-negotiable to prevent reinfection 3

On the same day as treatment:

• Machine wash and dry all bedding, clothing, and towels using hot cycle 1, 3, 4, 5
• OR dry clean these items 1, 3, 4
• OR seal in plastic bags and remove from body contact for at least 72 hours 1, 3, 4, 5
• Fumigation is unnecessary 1, 3, 4, 5

Comparative Efficacy Evidence

While both treatments are CDC-recommended first-line options, permethrin demonstrates faster symptom relief 6:

• Permethrin: 92.5-94.2% cure rate at 2-4 weeks 7
• Single-dose ivermectin: 85.9% cure rate at 2 weeks, requiring second dose 7
• Permethrin-treated patients recover earlier with more rapid improvement in lesions and pruritus 7, 6

Common Pitfalls to Avoid

Treatment failures occur due to:

• Inadequate application of topical treatment (missing body areas) 1, 4, 5
• Failure to treat all close contacts simultaneously 4, 5
• Not repeating ivermectin dose at 2 weeks 4, 5
• Premature retreatment due to persistent itching (which is normal for 2 weeks) 3, 4, 5
• Reinfection from untreated contacts or contaminated fomites 4, 5

Alternative Regimen (Only if First-Line Fails or Cannot Be Tolerated)

Lindane 1% should be avoided in this patient unless absolutely necessary 1:

• Apply 1 oz lotion or 30 g cream thinly from neck down, wash off after 8 hours 1
• Risk of neurotoxicity including seizures and aplastic anemia 1
• Do NOT use after bathing or if extensive dermatitis present 1
• Resistance reported in some U.S. regions 1