Be your dogs hero with fast-acting Advantus. Fleas not only cause discomfort. They may also transmit disease-causing organisms to your dog. These (imidacloprid) soft chews are available without a prescription and are indicated for the treatment of flea infestations on dogs and puppies 10 weeks of age and older and weighing 4 pounds or greater. Once your dog ingests the savory soft chew, the active ingredient, imidacloprid, spreads throughout your dogs body. When fleas feed, imidacloprid over-stimulates the fleas nervous systems, resulting in the fleas death. Advantus starts to kill fleas within 1 hour and achieves greater than 96 percent effectiveness in just 4 hours. Because Advantus does not have an effect on fleas in the environment, you must also address your pets surroundings. Should your dog may become re-infested. You can safely repeat treatment as often as once a day. 37.5 mg Soft Chews for Large Dogs 23-110 lbs. 7 count.