Our dogs have never had fleas before. I decided to get this in a quick attempt to make sure our first dog didn’t get fleas from our second dog that we got at the Humane Society. We noticed our first flea about 24 hours after applying. About seventy-two hours after application we had more fleas then I thought we’d be able to treat. My male dog never had fleas before and he was miserable. Unfortunately we are unable to treat them with any other flea medication for up to 30 days. This was almost like using sugar water to fight mosquitoes off. When dog ended up with worms. Both dogs ended up with fleas and scabs from the fleas. Luckily after the 30 days we were able to get their regular flea medication and both were cleared of fleas after 12 hours. I would not recommend this product to anyone and this company should not be allowed to produce any products for the animal.