5 Medications Known to Treat Canine Fleas

May 7th 2016

Because some chemicals kill fleas only in certain stages of growth, medications may have several active ingredients that work together to completely eliminate fleas. Discuss treatment options with your veterinarian to determine the proper course of action for your dog. With careful consideration and responsible use, these potent medications help keep your dog comfortable and safe from irritating flea infestation.


Nitenpyram, an active ingredient in the over-the-counter medication Capstar, begins killing fleas within six hours of ingestion. Owners may use this daily-dose medication on dogs as young as 4 weeks old. This medication is available as a flavored chewable tablet or as a pill to be swallowed whole. Some side effects include lethargy, hyperactivity, diarrhea or vomiting.


Veterinarians must prescribe spinosad. A popularly prescribed brand is Comfortis. This oral medicine, made from a substance produced by bacteria that grow naturally in soil, comes in chewable, beef-flavored tablets. Spinosad kills fleas and flea eggs as quickly as 30 minutes after ingestion and can be given to dogs 14 weeks of age or older. The most common side effect is vomiting.


Pyriproxyfen, the active ingredient in over-the-counter Advantage II products, prevents insects from hatching by killing flea eggs. This topical medicine lasts for 30 days and becomes waterproof just one hour after application on dogs 7 weeks of age and older. Use this medication exactly as directed to avoid negative side effects. Be alert for skin irritation.


Fipronil is the active ingredient in the over-the-counter medication Frontline Plus. It starts working within 12 hours of application on dogs 8 weeks of age and older. Similar to pyriproxyfen, this topical medication lasts 30 days per dose and is waterproof. This powerful treatment kills fleas by disrupting their nervous systems. Read instructions thoroughly and follow them exactly. Possible side effects include excessive drooling, diarrhea and loss of appetite.


Imidacloprid is an active ingredient in over-the-counter flea collars and K9 Advantix II topical products. This chemical works within 12 hours of application and lasts up to 30 days in liquid form. On flea collars, imidacloprid may last up to eight months. Similar to fipronil, this medicine disrupts the function of an insect

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