The insect growth regulator, which is known as pyriproxyfen, was added to the formula to make it a more complete flea and tick killing solution. The IGR ingredient makes it possible to kill fleas and ticks in all of their life stages. This is the main difference between regular K9 Advantix and K9 Advantix II.

Side Effects: Monitor your dog after application. Side effects, although very rare, may include signs of skin irritation such as redness, scratching, or other signs of discomfort. Gastrointestinal signs such as vomiting or diarrhea have also been reported.

Advantage II is available in a feline formula as well, while K9 Advantix II is made only for dogs. Advantage II contains Pyriproxyfen and Imidacloprid. K9 Advantix II combines the active ingredients of Pyriproxyfen, Imidacloprid, and Permethrin.

Starts to kill fleas, ticks and mosquitoes within 12 hours - half the time of other leading brands. No prescription needed. Effective on dogs and puppies 7 weeks of age and older that weigh 4 or more pounds.

The biggest difference between these medications is that K9 Advantix II kills AND repels fleas, ticks, mosquitoes, and chewing lice, but Frontline Plus kills these pests AND prevents fleas from laying new eggs. Pregnant dogs are also approved to use Frontline Plus, and vets must be consulted to use K9 Advantix II.

You'll want to opt for Seresto. If you would rather apply a topical product each month, K9 Advantix II is the way to go. If your dog is pregnant, breeding, or lactating, K9 Advantix II is the safest choice.

Allergic reactions and sensitivity While K9 Advantix II for dogs is safe when used as directed, it can be fatal for cats. Permethrin, one of the active ingredients in K9 Advantix II, is toxic to cats. Pet parents of cats and dogs must isolate their cats for at least 24 hours following treatment.

However, it is possible that some dogs may experience mild lethargy or fatigue as a side effect of K9 Advantix or other flea and tick medications. This is generally a temporary effect and should resolve on its own within a few days.

Allergic reactions and sensitivity While K9 Advantix II for dogs is safe when used as directed, it can be fatal for cats. Permethrin, one of the active ingredients in K9 Advantix II, is toxic to cats. Pet parents of cats and dogs must isolate their cats for at least 24 hours following treatment.

Advantage has formulations approved for both dogs and cats, while Advantix is intended for use in dogs only. Advantix causes permethrin toxicity in cats, which is a common emergency, especially during the spring and summer months when fleas are at their peak of peskiness.

Can I touch my dog after applying Advantix? Once the Advantix Plus has been fully absorbed by your dog's skin and coat and the treated area is dry, it is generally safe for other people and animals to touch your dog.

Advantix remains effective following shampooing with a soap-free shampoo, swimming or exposure to rain. Bathing your pet is not required prior to applying Advantix however your pet should not be allowed to swim or be shampooed within 48 hours after treatment. Avoid applying Advantix while the animal is wet.