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answers to how, when & why
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answers to how, when & why

FRONTLINE® Plus FAQs answered here.

Find out what you need to know about slaying fleas and ticks with the power of FRONTLINE Plus.

Just click on one of the frequently asked questions below.

dog laying

Q. How does FRONTLINE Plus kill fleas and ticks?

A. FRONTLINE Plus has 2 secret weapons: fipronil and (S)-methoprene. Once FRONTLINE Plus is applied, this combo stores itself in the oil glands in your pet's skin. It then self-distributes continuously for 1 month to your pet's hair and skin through the hair follicles. Fleas or ticks that come in contact with your pet are dead meat.

Q. How long does it take for FRONTLINE Plus to kill fleas?

A. In a study, FRONTLINE Plus began killing fleas 4 hours after application.1 Another study showed that within 12 hours, Frontline Plus killed 100% of fleas.2

Q. Do fleas and ticks have to bite my pet for FRONTLINE Plus to work?

A. No. FRONTLINE Plus kills fleas and ticks through contact with your pet's haircoat. No biting necessary.

Q. Why am I seeing more fleas on my pet after applying FRONTLINE Plus?

A. Fleas rise to the top of your pet's haircoat as they die. So if you start seeing more fleas after treating your pet, consider it a victory for the killing force.

Q. After using FRONTLINE Plus, I still see fleas in my home. Why?

A. The fleas you see most likely started as flea eggs that were deposited in the environment before you began using FRONTLINE Plus. Consecutive monthly applications of FRONTLINE Plus will assist with the elimination of an indoor flea life cycle. In some geographical regions in the United States, it may be required to use the product year-round.

Q. Does FRONTLINE Plus have an expiration date?

A. No. As long as you keep it at room temperature and sealed in its original packaging, FRONTLINE Plus will remain ready for battle.

Q. How long after application can my pet be bathed or go swimming?

A. FRONTLINE Plus remains effective for 30 days, even if your pet swims or is bathed. After application, keep your pet from getting wet for 24 hours. If FRONTLINE Plus is to be applied after a bath, make sure your pet is completely dry before application.

Q. Can I use it if my pet is on medication?

A. Before using FRONTLINE Plus, ask your vet about possible interactions with any medications your dog is taking.

Q. Can I use FRONTLINE Plus if I have already applied another flea and tick control product?

A. Before using, consult your veterinarian.

Q. Does FRONTLINE Plus kill anything else besides fleas and ticks?

A. You bet. FRONTLINE Plus also kills chewing lice.

Q. Can FRONTLINE Plus be used on pets other than dogs and cats?

A. No. FRONTLINE Plus should be used on dogs and cats only. There are specific products based on what kind of pet you have and how much it weighs. Be sure to use the right product for your pet.

Q. Can I apply it more than once a month?

A. Don't reapply FRONTLINE Plus before the month is through. It keeps working for a full 30 days.

Q. Where can I get FRONTLINE Plus?

A. Your vet's office is command central. Only there can you get expert advice, personal application instructions and special savings.

Q. How old does my pet need to be in order to have FRONTLINE Plus applied?

A. At 8 weeks your pet can start benefiting from the power of FRONTLINE Plus.


Questions to ask your vet
about FRONTLINE Plus.

See below for some questions to ask your vet before using FRONTLINE Plus on your pet for the first time:

Before using FRONTLINE Plus on your pet for the first time, make sure you speak with your vet. After all, your veterinarian is the most qualified professional to advise you on the health of your dog or cat.

Simply jot down these questions to ask him or her prior to your next visit.

  • I understand that fleas may seem like a nuisance. But do they really pose a serious health threat to my pet?
  • If I see a flea bite on my pet’s skin, how should I treat it?
  • What’s the likelihood that fleas and ticks could transmit diseases to my pet?
  • If I notice a tick on my pet, what’s the best course of action?
  • Should I use FRONTLINE Plus on my pet all year round? Or just during flea and tick season?


To learn more about FRONTLINE® or other MERIAL® products and services, write or call us. Thanks.

Merial Inc.
3239 Satellite Blvd., Building 500
Duluth, GA 30096-4640

Merial Customer Service
Monday–Friday, 8 AM–7 PM (ET)

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