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Frontline Plus

Written By Mel Lee-Smith
Published: 09/15/2020Updated: 08/30/2021
Frontline Plus for Dogs | Wag!

Frontline Plus for dogs is a topical flea and tick treatment. It also protects dogs from other parasites, including mites and chewing lice. Keep reading to discover dosage strengths, efficacy, side effects, and frequently asked questions about using Frontline Plus.


Frontline Plus for dogs comes in the following dosage strengths based on your dog’s weight:

  • 5 to 22 lbs. — 0.67 ml

  • 23 to 44 lbs. — 1.34 ml

  • 45 to 88 lbs. — 2.68 ml

  • 89 to 132 lbs. — 4.02 ml

Each dosage strength comes in a different colored package. Dogs must be 8 weeks of age or older to use Frontline Plus. They must also weigh at least 5 lbs.

Application instructions

Applying Frontline Plus for dogs only takes a few minutes. First, take off your dog’s collar. Remove all product packaging and snap the cap off the applicator.

Gently brush the fur between the shoulder blades to create a parting exposing the skin. Apply the full dose directly to your dog’s skin in a single spot. Avoid touching the medication once applied, and wash your hands well with soap and warm water afterward.

Your dog shouldn’t be able to lick the area between their shoulder blades, but supervise them until the medication dries just in case. Avoid letting your dog swim or bathe for 24 hours after applying. You’ll need to apply this topical treatment once every 30 days.


One study found that Frontline Plus is 100% effective in treating all life stages of fleas and ticks within 12 to 24 hours following treatment. Frontline Plus works by translocation. This is the process by which the medication spreads all over your dog’s body through the oil glands.

Active ingredients in Frontline Plus for Dogs

Fipronil (9.8%) and (S)-methoprene (8.8%) are the active ingredients in Frontline Plus for dogs.

As well as treating fleas, ticks, lice, and mites, fipronil also kills chiggers and treats sarcoptic mange. This fast-acting ingredient starts working as soon as it’s applied. The first parasites will begin to die off in as little as 4 hours.

S-methoprene is a form of methoprene, a common pesticide used against beetles, flies, and other insects in addition to parasites that prey on dogs. Methoprene works by inhibiting an insect’s growth. This is why it’s so effective in preventing eggs and larvae from maturing into adults. It also prevents reproduction in adult parasites.

Side effects

Frontline Plus for dogs is generally safe to use and causes few side effects. Mild skin irritation may occur but should clear up quickly. Additional side effects may include vomiting, diarrhea, and seizure. However, these side effects are extremely rare and tend to affect smaller dogs. If you have any questions or concerns about potential side effects, contact your veterinarian.


Drug interactions

To date, no drug interactions with Frontline Plus have been recorded. However, be sure to discuss your dog’s current medications, prescribed or otherwise, with your vet prior to applying.

Allergic reactions and sensitivity

Some pets are allergic to fipronil, one of the active ingredients in Frontline Plus. If you notice any adverse reactions after applying, consult your vet before applying the next dose.

Frequently asked questions

What’s the difference between Frontline and Frontline Plus?

Frontline only protects dogs from adult fleas. Frontline Plus protects against a wide range of parasites, including all life stages of fleas and ticks, as well as certain species of lice and mites.

Do I need a prescription for Frontline Plus?

No. Frontline Plus is available over-the-counter. Read the package carefully to ensure you purchase the correct dosage strength for your dog.

What should I do if I miss a dose?

Reapply it as soon as you remember, and wait a full 30 days before applying the next dose. Consider setting a reminder on your phone or calendar.

Is it safe to apply more than one dose within 30 days?

No. The recommended dosage protects dogs for a full 30-day period.

Can I treat puppies and pregnant dogs with Frontline Plus?

Frontline Plus is safe for puppies over 8 weeks of age and 5 lbs., as well as pregnant and lactating dogs.

What should I do if my dog licks the medicine?

Contact your veterinarian immediately. Although serious side effects are rare, ingestion of any poison can cause adverse symptoms 

I applied Frontline Plus, but now my dog has more fleas. Why?

It may appear that your dog has more fleas following treatment, but this likely isn’t the case. Frontline Plus draws parasites to the surface of your dog’s coat, increasing their visibility. They should start to die off within 18 hours.

I still see fleas in my home and yard even after using Frontline Plus. What should I do?

When using any topical flea treatment, you must also treat the environment. Insect control products, specifically those containing nematodes, are effective in killing fleas living in your yard. Nematodes are a type of roundworm that lives in soil. These roundworms won’t affect your pet, although you should ensure your dog doesn’t consume any pest control products.

To get rid of fleas inside your home, you’ll want to wash all your bedding (including your own as well as your dog’s) in hot water. Powerful vacuums, steam cleaners, and pest control products are also effective.

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© 2024 Wag Labs, Inc. All rights reserved.

© 2024 Wag Labs, Inc. All rights reserved.