Johnson's Herbal flea Drops for dogs consists of two vials containing 0.75ml of a mixture of natural plant oils & extracts. Contains 0.5% w/w margosa extract, micro-encapsulated citronella, peppermint and eucalyptus oils in an aqueous base. New water based non-greasy formulation, protects for up to 4 weeks. Advanced micro-encapsulated formula, requiring a small dose and giving improved efficacy. When applied, the drops migrate naturally through the coat but may take a few days to be fully effective. This product does not contain an insecticide but clinical trials have proved it to be effective. It also contains a bitter solution to deter dogs from licking their fur after treatment.