Fipronil for Cats - Dosage, Uses and Side Effects

Laura García Ortiz
By Laura García Ortiz, Veterinarian specialized in feline medicine. June 6, 2022
Fipronil for Cats - Dosage, Uses and Side Effects

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Fipronil (brand names: Frontline®, Barricade®, Easyspot® and many others) is a broad-spectrum insecticide used to control insects such as fleas, lice, ticks, cockroaches, and mites. Cats can be treated with it for external parasites and for allergic dermatitis after flea bites starting at the age of two months, when they weigh more than 2 pounds (0.91 kilogram).

In this AnimalWised article, we explain what Fipronil is in cats, what it is used for, how it is dosed, and its side effects.

  1. What is Fipronil?
  2. What is Fipronil used for in cats?
  3. How to apply Fipronil in cats
  4. Side Effects of Fipronil in Cats
  5. Contraindications of Fipronil in cats

What is Fipronil?

Fipronil is an active ingredient of the phenylpyrazole group, a broad-spectrum insecticide that acts by contact and has a large residual effect after application.

Fipronil disrupts the central nervous system of certain parasites such as fleas, ticks, and lice and causes hyperexcitation of the nerves and muscles of the infested insects. It does not have this effect in vertebrates, such as cats or dogs, making it a safe medication for these animals.

Fipronil is often used in combination with other drugs to treat a variety of topical parasites.

Because of its effectiveness against a wide range of pests, Fipronil is used as an active ingredient in flea control products for pets and in cockroach traps for household use. It is also used for pest control in fields, golf courses and commercial lawns.

What is Fipronil used for in cats?

Fipronil is used in cats as an external antiparasitic to treat and prevent infestation by ectoparasites or external parasites such as fleas, lice, and ticks. It is sometimes used in conjunction with flea development inhibitors such as pyriproxyfen or metroprene to increase efficacy against fleas in immature stages.

It is intended for domestic animals such as cats, dogs, and cattle. In cats, it is always applied topically in the form of a pipette or spray to kill and prevent external parasites, but not internal parasites. So, to cover the entire antiparasitic spectrum, you must also deworm your cat internally.

Fleas begin to die between 4 and 8 hours after application. It may take 12 hours or longer for ticks to die and fall off and clinical signs to improve.

How to apply Fipronil in cats

Fipronil is applied topically to the skin or coat. Fipronil for cats is available in two formats: Spray and spot-on (pipettes).


When using the spray, apply it by ruffling your pet's fur with one hand and spraying the skin and fur with the other. Do not spray the spray directly on the head or face. Spray it on a gloved hand and then gently rub it into the hair on the head. Do not get the product in your pet's mouth or eyes, and do not use on irritated skin.

This product eliminates fleas with a single contact and protects against fleas for 2 months and ticks and lice for 4 weeks. Each spray of this spray delivers 0.5 ml of product. Approximately 3 ml/kg is needed for short-haired cats, and up to twice that amount, 6 ml/kg, for long-haired cats.

The entire surface of the cat should be sprayed evenly, keeping the bottle at a distance of 10-20 cm from the animal. After application, it must be rubbed in so that the drug can penetrate the skin and exert its effect. Let it dry naturally without using a hair dryer or towel. You should apply it in a well-ventilated area.


When using a pipette, spread the drops directly onto the skin by parting the hair between your pet's shoulder blades and at the base of the neck. Then, place the applicator tip directly on the skin, and squeezing to release the contents. Typically, the dose of Fipronil in pipettes that have a concentration of 10% or 25% is 1 pipette of 0.5 ml per cat.

Avoid contact with skin, eyes, or clothing. Wear gloves when applying and avoid contact with your pet until it is dry. If the medicine gets on your skin, wash it off well with soap and water. Do not bathe your pet with a shampoo within 48 hours after application.

Side Effects of Fipronil in Cats

The use of Fipronil in cats is safe and effective, but side effects such as the following may occur very sporadically:

  • Hypersalivation (if ingested)

  • Vomiting

  • Dandruff, itching, alopecia, or erythema at the application site.

  • Neurologic signs (ataxia, tremors, lethargy, seizures, hyperesthesia).

  • Respiratory signs after inhalation of the product.

Fipronil overdose in cats

Safety studies have evaluated the use of doses up to five times the indicated dose in cats over a 6-month period. No adverse reactions were observed in cats older than 9 weeks and weighing 1 kg. However, the adverse reactions listed above may be more likely. Fipronil poisoning in cats can be dangerous at higher doses and needs veterinary treatment in order to remove or neutralize the toxin from the body.

External parasites are one of the most problematic issues that can affect a cat's well-being. Not only can they cause superficial problems in the form of hair loss and itching, but they can also transmit life-threatening diseases. Read the following article to learn more about the most common external parasites in cats.

Contraindications of Fipronil in cats

Contraindications to the use of Fipronil in cats are as follows:

  • Pipettes with a 10% concentration should not be administered to cats less than 8 months old or weighing less than 1 kg.

  • Pipettes containing 25% should not be given to cats under 9 months of age or weighing less than 1 kg.

  • Do not use in sick animals with systemic disease, weakness, or fever.

  • Do not use in rabbits because serious adverse effects, including death, may occur.

  • Do not spray Fipronil Spray on injured skin or wounds.

  • Do not use the product if you are hypersensitive to any of the recipients in the product.

External and internal deworming is incredibly important to the health of our pets. However, many pet owners are still unaware of the importance of antiparasitic. Owners who do not deworm their pets are exposing them to infection that can lead to discomfort, illness, and even death. Read the following article if you want to learn more about the importance of deworming your pet.

This article is purely informative. AnimalWised does not have the authority to prescribe any veterinary treatment or create a diagnosis. We invite you to take your pet to the veterinarian if they are suffering from any condition or pain.

If you want to read similar articles to Fipronil for Cats - Dosage, Uses and Side Effects, we recommend you visit our Medicine category.

  • Spanish Agency for Medicines and Medical Devices. Frontline prospect spot-on cat 10%.
  • Spanish Agency for Medicines and Medical Devices. Frontline prospect spot-on cat 25%. Available at:
  • Spanish Agency for Medicines and Medical Devices. Leaflet Frontline Spray 100 ml . Available at:
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Fipronil for Cats - Dosage, Uses and Side Effects