- No studies of the passage of malathion or permethrin into human breast milk following topical application have been located.
- Percutaneous absorption of malathion is about 4%. Malathion is rapidly destroyed by plasma cholinesterases.
- Percutaneous absorption of permethrin is less than 2%. Permethrin is rapidly metabolised by serum and tissue enzymes to inactive metabolites and rapidly excreted in the urine.
- Theoretical considerations would indicate that the amount of drug passing into milk after topical application would be too low to present a hazard to the breastfeeding infant.
- Either malathion or permethrin topical preparations may be used to treat pubic lice infestations in breastfeeding mothers of full term, healthy infants.
Acting Co-Director, West Midlands Medicines Information Service & UK Drugs in Lactation Advisory Service