Frontline Plus is a globally recognized veterinary brand of topical parasite prevention products designed for dogs and cats. It is primarily used to kill and prevent fleas, ticks, and chewing lice, while also interrupting the flea life cycle by preventing flea eggs and larvae from developing. The product is widely used by veterinarians and pet owners and is sold in more than 100 countries.

Originally developed by Merial, the Frontline brand later became part of Boehringer Ingelheim Animal Health following the acquisition of Merial in 2017. Today, Frontline Plus remains one of the company’s flagship companion animal healthcare brands. 1

Frontline was first introduced during the 1990s as one of the earliest modern flea and tick control products based on fipronil, a broad-spectrum insecticide.

To improve effectiveness against flea infestations, Merial later launched Frontline Plus, which added (S)-methoprene, an insect growth regulator (IGR). This combination allowed the product not only to kill adult fleas and ticks but also to prevent flea eggs and larvae from developing, reducing reinfestation in the pet’s environment. 2

In 2017, Merial merged into Boehringer Ingelheim Animal Health, making Frontline one of its leading companion animal brands. 3

Fipronil

Fipronil is an insecticide and acaricide that targets the nervous system of parasites.

It is effective against:

• Fleas
• Ticks
• Chewing lice

Unlike systemic medications, fipronil spreads across the pet’s skin and hair coat after application rather than entering the bloodstream. Parasites are generally affected through contact with treated skin and coat. 1

(S)-Methoprene

(S)-Methoprene is an insect growth regulator (IGR).

Instead of killing adult parasites directly, it prevents flea eggs and larvae from developing into adult fleas.

This helps break the flea life cycle and reduces environmental infestations. 4

After being applied to the skin:

1. The solution spreads through the oils on the skin.
2. It accumulates in sebaceous (oil) glands.
3. These glands gradually release the medication over approximately one month.
4. Fleas and ticks contacting the treated coat are killed.
5. Flea eggs and larvae are prevented from maturing due to (S)-methoprene. 1

Frontline Plus provides:

• Flea treatment
• Flea prevention
• Tick control
• Chewing lice control
• Prevention of flea egg development
• Monthly protection
• Waterproof protection after the product has dried (following label directions) 1

Frontline Plus is sold in different dosage sizes based on animal species and body weight.

Dogs

Available for:

• Small dogs
• Medium dogs
• Large dogs
• Extra-large dogs

Each weight range has a different pipette size containing the appropriate dose.

Cats

Available as a dedicated feline formulation.

The cat product is specifically formulated for cats and should not be substituted with the dog version. Veterinary product registrations in multiple countries list distinct formulations for dogs and cats.

Frontline Plus is supplied in single-use pipettes.

General application steps:

1. Remove the pipette.
2. Part the hair between the shoulder blades.
3. Apply directly to the skin.
4. Empty the entire contents.
5. Allow the application site to dry naturally.

The product is generally intended for monthly application according to the label.

Common advantages include:

• Long-established brand with decades of use.
• Dual-action formula against adult fleas and immature flea stages.
• Non-oral administration.
• Suitable for dogs and cats (using the correct species-specific formulation).
• Widely available through veterinarians, pet retailers, and pharmacies in many countries. 2

Frontline Plus is intended for:

• Dogs (dog formulation)
• Cats (cat formulation)

Users should:

• Follow species-specific instructions.
• Avoid applying dog formulations to cats unless explicitly indicated by the manufacturer.
• Prevent pets from licking the application site until it is dry.
• Use only the dose appropriate for the pet’s weight and age as indicated on the product label. 1

Frontline Plus is marketed internationally and is registered with veterinary regulatory authorities in many countries, including Europe, North America, Asia, and Australia. Country-specific registrations may differ in packaging, dosage strengths, and labeling requirements.

Frontline Plus has been one of the best-known flea and tick treatment brands for more than two decades and has extensive real-world use.

At the same time, veterinary guidance has evolved, and newer topical and oral parasite preventives have become available. Some veterinarians and pet owners report excellent results with Frontline Plus, while others—particularly in areas with heavy flea pressure—may prefer newer alternatives. Product choice often depends on the local parasite species, resistance patterns, the pet’s health, and veterinary advice. 2

The Frontline product family includes:

• Frontline Spot On
• Frontline Plus
• Frontline Gold (available in some markets)
• Frontline Spray
• Frontline Tri-Act (dogs only in selected regions) 3

Frontline Plus is a long-established veterinary parasite prevention brand that combines fipronil and (S)-methoprene to control fleas, ticks, and chewing lice while disrupting the flea life cycle. Its topical, monthly application and broad international availability have made it one of the most recognized flea and tick products for companion animals, although veterinarians may recommend different preventive options depending on regional parasite risks and the individual pet’s needs. 2

1. IN PARTNERSHIP WITH ROYAL CANIN
2. Tackling fleas and ticks – FRONTLINE PLUS®
3. FDA Verification Portal
4. Products | Square Pharmaceuticals PLC.