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malathion

P03AX03

Forms & Strengths

Lotion: 0.5% (in isopropanol base)

Adult Dosing

Pediculosis capitis: Apply lotion to dry hair in an amount sufficient to thoroughly wet hair and scalp, rub gently, allow to dry naturally without a hair dryer, wash thoroughly with shampoo after 8-12 hours, rinse, and use a fine-toothed comb to remove nits. Repeat in 7-9 days only if live lice are still observed.

Pediatric Dosing

Pediculosis capitis (Ages 2 years and older): Same as adult dosing. Safety and efficacy have not been established in pediatric patients under 2 years of age.

Indications

Treatment of head lice (Pediculosis capitis) and their ova

Mechanism of Action

Organophosphate insecticide that inhibits cholinesterase in both adult lice and ova, causing paralysis and death of the parasite.

Contraindications

Hypersensitivity to malathion or any of its formulation components
Neonates and infants under 2 years of age (due to potential increased permeability of the scalp and risk of systemic toxicity/CNS depression)
Use near an open flame or electric heat source (due to flammable isopropanol vehicle)

Adverse Reactions

Chemical burn
Scalp irritation
Erythema
Stinging
Contact dermatitis
Temporary hair loss

Drug Interactions

Cholinesterase inhibitors (systemic toxicity risk may be theoretically increased if absorbed)
None significantly documented with topical application when used as directed due to minimal systemic absorption, though caution is advised with other topical scalp treatments

Curated Content: Needs Vetting Before Put to Clinical Use