Insect growth regulators
Also appears on labels as: pyriproxyfen, (s)-methoprene, s-methoprene, methoprene
Insect hormone mimics, pyriproxyfen and methoprene, that act on flea eggs and larvae rather than on adult fleas.
Watched ingredients get highlighted on every product panel you open.
- Where it comes from
- Chemical synthesis.
- Why it's in the product
- Paired with an insecticide that acts on adult fleas.
- Safety and toxicity
- The Merck Veterinary Manual notes pyriproxyfen's low toxicity to mammals. It is flagged all the same, as a pesticide active, like every active in this aisle.
We make the longer argument about this one on the pesticide actives evidence page.
General reference, not veterinary advice. Dose, breed, and existing conditions change the answer, so talk to your vet before changing what your pet eats. Think we got this wrong? Tell us and we log it publicly.
Found in 6 scored products
Lowest scores first. Its presence here is not what drove those scores.
