By Rania Gollakner, BS, DVM, MPH

What is fipronil?

Fipronil (brand names: Frontline®, Barricade®, Easyspot®, Effipro®, Sentry Fiproguard®, Parastar®, PetArmor®, Pronyl OTC®, Spectra Sure®, and many others) is a topical medication used to treat fleas, ticks, and chewing lice infestations in dogs and cats. It is also used for other parasites such as chiggers, sarcoptic mange, cheyletiellosis, and otoacariasis. Fipronil is frequently found in combination with other medications to treat a wide variety of topical parasites.

Its use in cats and dogs to treat certain parasites is ‘off label’ or ‘extra label’. Many drugs are commonly prescribed for off label use in veterinary medicine. In these instances, follow your veterinarian’s directions and cautions very carefully as their direction may be significantly different from those on the label.

How quickly does it kill fleas and ticks?

Fleas will start to die between 4 to 8 hours after application. Ticks may take 12 hours or longer to die and fall off and improvement in clinical signs should follow.

How is fipronil given?

Fipronil is applied topically to the skin or haircoat. Apply the drops directly to the skin by parting your pet’s hair between the shoulder blades and at the base of the neck, applying the applicator tip directly to the skin, and squeezing the application to empty the contents. Apply the spray by ruffling your pet’s coat with one hand while spraying the skin and coat with the other hand. Do not spray directly onto the head or face; spray on a gloved hand and then gently rub into the hair on the head. Do not get in your pet’s mouth or eyes, and do not apply to irritated skin.

Avoid human contact with skin, eyes, or clothing; wear gloves when applying, and avoid contact with your pet until dry. If the medication gets on your skin, wash well with soap and water. When using the spray form, use in a well-ventilated area. Do not bathe with shampoo within 48 hours of application. Twenty-four hours after application, exposure to water or sunlight should not affect the effectiveness of this medication.

What if I forget to give my dog/cat/pet the medication, or my shipment is late?

Apply the missed dose as soon as you remember, and then wait the recommended amount of time between doses. Never give your pet two doses at once or give extra doses.

If prescribed for monthly application, give the dose as soon as you remember and start a new monthly dosing schedule. For example, if you forgot to give your pet his/her dose on June 1 and remember on June 18, give the dose on June 18 and start a new monthly schedule. The next dose your pet will receive would be on July 18. Do not give your pet two doses at once. Contact your veterinarian if you are concerned about a missed dose.

Are there any potential side effects?

Side effects are uncommon. Temporary irritation at the application site may occur, and rarely an allergic reaction of the skin may occur. This long-acting medication lasts for at least 4 – 6 weeks, and may last longer in pets with kidney or liver disease.

Are there any risk factors for this medication?

Do not use fipronil on pets that are allergic to fipronil, on puppies or kittens younger than 8 weeks of age, or on rabbits. Fipronil should be used cautiously on pets that are old, sick, or frail.

Are there any drug interactions I should be aware of?

There are no specific drug interactions with fipronil. Be sure to tell your veterinarian about any medications (including vitamins, supplements, or herbal therapies) that your pet is taking.

Is there any monitoring that needs to be done with this medication?

There is no specific monitoring that needs to be done while your pet is taking this medication. Your veterinarian may monitor your pet to be sure that the medication is working.

How do I store fipronil?

Store this medication away from heat or an open flame.

What should I do in case of emergency?

If you suspect an overdose or an adverse reaction to the medication, call your veterinary office immediately. If they are not available, follow their directions in contacting an emergency facility.

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