Permethrin 5% Lotion: Indications and Side Effects
Permethrin 5% cream is FDA-approved exclusively for the treatment of scabies (Sarcoptes scabiei infestation), applied overnight for infants as young as 2 months of age 1.
Primary Indication
- Scabies treatment: The only FDA-approved indication for 5% permethrin 1
- Applied to entire skin surface from neck down
- Safe for infants ≥2 months of age 2
Off-Label Use (Not FDA-Approved)
Permethrin 5% has been used anecdotally for treatment-resistant head lice, but this is NOT FDA-approved 2. Evidence suggests that lice resistant to 1% permethrin will not respond to higher 5% concentrations 2, making this approach questionable.
Side Effects
Common (Mild and Transient)
- Burning and stinging (10% of patients) - severity correlates with infestation burden 1
- Pruritus/itching (7% of patients) - can occur at various times post-application 1
- Erythema (1-2% or less) 1
- Numbness and tingling (1-2% or less) 1
- Rash (1-2% or less) 1
Post-Marketing Reports (Rare)
- Headache
- Fever
- Dizziness
- Abdominal pain
- Diarrhea
- Nausea/vomiting 1
Extremely Rare
- Seizures: Reported but extremely uncommon when used as directed; none medically confirmed as directly associated with permethrin 5% 1
Important Clinical Considerations
Contraindications: Known hypersensitivity to permethrin, synthetic pyrethroids, or pyrethrins 1
Post-treatment itching: Itching or mild burning from skin inflammation can persist for many days after mites are killed and is NOT a reason for retreatment. Manage with topical corticosteroids and oral antihistamines 2
Application technique: Rinse over a sink (not shower/bath) with warm (not hot) water to minimize systemic absorption 2
Emerging resistance: Recent high-quality evidence from 2024 shows only 27% cure rate with permethrin 5% versus 87% with benzyl benzoate, suggesting significant resistance development 3. A 2026 meta-analysis confirms permethrin demonstrates modest superiority over ivermectin but emphasizes the need for optimized treatment strategies 4.