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
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
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
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
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
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-launderables for minimum 2 days (or 3 weeks for rigorous approach) 8
- Fumigation of living areas is unnecessary 1, 2, 3
Contact Treatment
- Examine and treat all sexual, close personal, and household contacts within the preceding month 1, 2, 3, 10
- All contacts must be treated simultaneously to prevent reinfection 2, 3, 8
- For institutional outbreaks, treat entire at-risk population 2
- Avoid sexual contact until patients and partners treated and reevaluation confirms no persistent infection 1
Follow-Up and Management of Persistent Symptoms
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 does not indicate need for retreatment 4
When to Retreat
- Retreatment indicated only 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 or live mites present 2, 3
Common Reasons for Treatment Failure
- Failure to treat all close contacts simultaneously 2, 3
- Inadequate application of topical treatments (missing scalp/face, under fingernails) 2, 3, 8
- Not repeating ivermectin dose after 2 weeks 2, 3
- Reinfection from untreated contacts or contaminated fomites 2, 3
- Medication resistance 1, 8
- Using lindane after bathing or in contraindicated populations 2, 3
Critical Pitfalls to Avoid
- Do not expect immediate symptom resolution—itching can persist 2 weeks post-treatment 2, 3, 4
- Do not skip scalp/face application in infants, elderly, or immunocompromised patients 1, 4, 6
- Do not forget to apply medication under fingernails 7, 8
- Do not use single-dose therapy for crusted scabies—combination therapy is mandatory 3
- Do not fail to treat contacts simultaneously—this is the most common cause of treatment failure 2, 3, 8
- Do not use lindane as first-line or in contraindicated populations 1, 2, 3
- Do not forget the second ivermectin dose at 2 weeks 1, 2, 3