Advantage vs Advantage II

Advantage II for cats

Differences Between Advantage I & Advantage II For Cats


There is one key difference between Advantage I (also known as Advantage 18) and Advantage II The Advantage I formula was not designed to kill fleas at all life stages. Advantage I only killed adult fleas. Advantage II is formulated to kill the flea eggs and larvae also, effectively destroying the flea life cycle. There are also modifications to the chemicals contained in Advantage II, as the fleas naturally develop a resistance to old formulas. The slight changes in the Advantage II formula bypass the flea’s natural resistance. There are three key ingredients in Advantage II for cats that are not contained in Advantage I- pyriproxyfen, imidacloprid and pyriproxyfen. These ingredients are insect growth regulators and the chemical for stopping the growth of new flea larvae & flea eggs.

Because of these formula differences, Advantage II is much more effective than Advantage ! for total flea control on your cats. You may be able to find some left over stock of the original Advantage for cheaper, but it will not work as well and will likely not fully take care of your flea problems.

Always be sure to buy the real Advantage II medication and avoid knock offs or “kits” being sold as the real thing. These can be dangerous for your cat’s health and may result in an emergency trip to the vet.

Here are some links to cheap Advantage II for cats, This is where I buy my Advantage II and its the cheapest I’ve been able to find anywhere.

The different colors are related to the size of the cat. Advantage II Orange is for smaller cats and Advantage II Purple is for large cats.

For large cats that are 9 pounds or more: Bayer Advantage II Purple 6-Month Flea Control for Cats 9+ lbs. – this includes 6 doses for a great price

The 6 dose pack is the best deal, but for cheaper there’s the 4 dose pack: Bayer Advantage II Purple 4-Month supply

For small cats 9 pounds or under, there’s: Bayer Advantage II Orange 4-Month Flea Control for Cats 5-9 lbs.

Source: Differences between Advantage Advantage II



I have recently started ordering Advantage II kits from and I really recommend these kits! They are way cheaper than buying retail packs, and a great way to save money on your kitty’s flea meds. These kits are used by breeders and rescue shelters, and contain the same Advantage II medication, just in larger sized doses that are measured down to a cat sized dose.