Frontline® for Dogs and Cats: Uses, Directions and Side Effects
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Frontline® products are topical flea and tick preventives for dogs and cats that help protect against fleas, ticks, and, in some formulations, additional parasites.
Each product contains different active ingredients and is designed for specific species and parasite protection.
Here’s how Frontline®, Frontline® Plus, Frontline® Gold, and Frontline® Shield work, how to apply them correctly, potential side effects, and important safety information.
Key Takeaways
- Frontline® products kill fleas and help protect dogs and cats from ticks, with parasite coverage varying by product.
- Always use the Frontline® product labeled for your pet's species and weight.
- Most Frontline® products are applied to the skin once a month for continuous protection.
- Side effects are uncommon but may include mild skin irritation at the application site.
- Frontline Shield® is for dogs only and should never be used on cats because it contains permethrin.
What Is Frontline® Used for in Dogs and Cats?
Frontline® products are topical parasite preventives that kill adult fleas and help prevent flea infestations in dogs and cats. Depending on the product, they also protect against ticks and certain other parasites.
Because Frontline® products are formulated by species and body weight, it's important to use the correct product for your pet.
Never use cat flea and tick products on a dog or dog flea and tick products on a cat, as this can lead to ineffective treatment or an overdose.
| Product | Species | Fleas | Ticks | Chewing Lice | Mosquitoes/Stable Flies |
| Frontline® Plus | Dogs | ✓ | ✓ | ✓ | — |
| Frontline® Plus | Cats | ✓ | ✓ | ✓ | — |
| Frontline® Gold | Dogs | ✓ | ✓ | ✓ | — |
| Frontline® Gold | Cats | ✓ | ✓ | — | — |
| Frontline® Shield | Dogs | ✓ | ✓ | ✓ | ✓ |
Frontline® Plus
Frontline® Plus for dogs helps protect against:
- Fleas
- Brown dog ticks
- American dog ticks
- Lone Star ticks
- Deer ticks
- May also help control chewing lice and sarcoptic mange
Approved for puppies and dogs 8 weeks of age and older weighing at least 5 pounds.
Frontline® Plus for cats helps protect against:
- Fleas
- Brown dog ticks
- American dog ticks
- Lone Star ticks
- Deer ticks
- May also help control chewing lice
Approved for kittens and cats 8 weeks of age and older weighing at least 1.5 pounds.
Frontline® Shield (Dogs Only)
Frontline® Shield for dogs helps protect against:
- Fleas
- Ticks
- May also help control chewing lice
- May also help control sarcoptic mites
- Repels mosquitoes and stable flies
Approved for puppies and dogs 9 weeks of age and older weighing at least 5 pounds. Do not use on cats.
Frontline® Gold
Frontline® Gold for dogs helps protect against:
- Fleas
- Ticks
- May also help control chewing lice
Approved for puppies and dogs 8 weeks of age and older weighing at least 5 pounds.
Frontline® Gold for cats helps protect against:
- Fleas
- Ticks
Approved for kittens and cats 8 weeks of age and older weighing at least 1.5 pounds.
Safety Considerations for Frontline® Products
Frontline® products are safe for most dogs and cats when used as directed, but some pets may require additional precautions.
Talk with your veterinarian before using Frontline® if your pet has skin disease, is debilitated, is a senior pet, or is taking other medications.
Frontline® Plus and Frontline® Gold for Cats: Approved for use in breeding, pregnant, and nursing cats.
Frontline® Plus and Frontline® Gold for Dogs: Approved for use in breeding, pregnant, and nursing dogs.
Frontline® Shield for Dogs: At the time of publication, safety studies had not been performed in breeding, pregnant, or nursing dogs. However, the manufacturer considers its use acceptable in many cases.
Talk with your veterinarian before using Frontline® Shield in breeding, pregnant, or nursing dogs.
How Frontline® Products Work
Frontline® products work by spreading through your pet's skin oils, where the active ingredients kill fleas, ticks, and other parasites through contact with the skin and coat.
Most Frontline® products provide protection for 30 days.
Active ingredients by product:
- Frontline® Plus: Contains fipronil and (S)-methoprene.
- Frontline® Gold: Contains fipronil, (S)-methoprene, and pyriproxyfen.
- Frontline® Shield (dogs only): Contains fipronil, pyriproxyfen, and permethrin.
How the active ingredients work:
- Fipronil: Kills adult fleas and ticks by disrupting normal signaling in the parasites' nervous system.
- (S)-methoprene and pyriproxyfen: Insect growth regulators that help prevent flea eggs and larvae from developing into adults.
- Permethrin: Kills and repels certain parasites but is not safe for cats, which is why Frontline® Shield should never be used in cats.
How To Apply Frontline® Products
Frontline® products are topical medications that should be applied directly to your pet's skin once a month. Always follow the product label or your veterinarian's instructions.
When applying Frontline®:
- Part your pet's fur and apply the entire contents of the applicator directly to the skin.
- For dogs, apply the medication between the shoulder blades.
- For cats, apply the medication at the base of the neck.
- Do not allow your pet to ingest the medication.
Bathing instructions:
- Wait 24 hours after applying Frontline® Shield before bathing your pet.
- Wait 48 hours after applying Frontline® Plus or Frontline® Gold before bathing your pet.
- If bathing before application, wait until your pet is completely dry before applying a Frontline® product.
Apply Frontline® Plus, Frontline® Gold, or Frontline® Shield every 30 days for continuous parasite protection.
What Happens If You Miss a Dose of Frontline®?
If you miss a dose of Frontline® Plus, Frontline® Gold, or Frontline® Shield, apply it as soon as you remember, then resume your pet's regular monthly dosing schedule.
For continuous parasite protection, apply Frontline® products every 30 days.
Do not apply extra or double doses.
Frontline® Side Effects
Frontline® products are well tolerated by most dogs and cats, but mild side effects can occur after application.
Possible side effects include:
- Itching, redness, or irritation at the application site
- Drooling
- Vomiting
- Diarrhea
If your pet develops skin irritation, bathe them with mild soap and plenty of water. Contact your veterinarian if the irritation is severe or does not improve.
Human Side Effects
Frontline® products are not intended for human use and can be harmful if swallowed.
When handling Frontline®:
- Avoid touching the treated area until it is completely dry.
- Wash your hands thoroughly with soap and water after applying the product.
If you accidentally ingest Frontline® or get it in your eyes, seek medical attention or call Poison Control at 800-222-1222.
Monitoring Your Pet
No specific monitoring is required while your pet is using Frontline®, although your veterinarian may recommend routine parasite screening during annual wellness exams or additional monitoring based on your pet's individual health needs.
When Should You Call Your Veterinarian?
Contact your veterinarian if:
- Your pet develops severe side effects.
- Your pet's condition worsens or does not improve.
- You suspect your pet has received an overdose.
- You have additional questions or concerns about using Frontline® products.
Frontline® Overdose
An overdose of Frontline® products can cause different symptoms depending on which product was used and whether it was applied to the skin or ingested.
If you suspect your pet has received too much Frontline®, seek veterinary care immediately.
Topical overdose symptoms may include:
- Scratching
- Rolling
- Itchiness
- Agitation
- Crying or whimpering
If a pet ingests Frontline®, symptoms may include:
If you suspect an overdose, seek emergency veterinary care or contact an animal poison control center. Consultation fees may apply.
- Pet Poison Helpline: (855) 764-7661
- ASPCA Animal Poison Control: (888) 426-4435
How To Store Frontline® Products
Store Frontline® products according to the label instructions to help maintain their safety and effectiveness.
Storage instructions:
- Store at controlled room temperature.
- Keep away from heat and open flames.
- Keep the medication in its original container until you're ready to use it to protect it from moisture and light.
- Keep out of reach of children and pets.
Frontline® for Dogs and Cats FAQs
How long does Frontline® take to work?
Frontline® starts working within a few hours of application and reaches full effectiveness after about 24 hours.
Does Frontline® kill all flea life stages?
No. Frontline® kills adult fleas on your pet and helps prevent flea eggs and larvae from developing.
However, it does not kill flea eggs, larvae, pupae, or adult fleas that are already present in your home or yard.
Can I bathe my pet after applying Frontline®?
No. Your pet should remain dry for at least 24 hours after applying Frontline®.
If you need to bathe your pet before application, wait until they are completely dry before applying the medication.
What if my pet licks Frontline®?
If your pet licks Frontline® shortly after application, they may drool excessively because of the medication's bitter taste.
This is usually temporary. However, if your pet develops persistent drooling, tremors, loss of coordination, seizures, lethargy, vomiting, or loss of appetite, contact your veterinarian immediately, seek emergency veterinary care, or call an animal poison control center.
Can I use Frontline® Shield on cats?
No. Frontline® Shield should never be used on cats.
It contains permethrin, which is highly toxic to cats and can cause severe illness or death. Frontline® Shield is formulated for dogs only.
Do I need a prescription for Frontline®?
No. Frontline® products are available over the counter.
What is the difference between Frontline® Plus and Frontline® Gold?
Frontline® Gold contains an additional insect growth regulator (pyriproxyfen) that helps prevent flea infestations by stopping immature flea stages from developing.
How often should I apply Frontline®?
Frontline® Plus, Frontline® Gold, and Frontline® Shield should be applied once every 30 days for continuous flea and tick protection.
No vet writer or qualified reviewer has received any compensation from the manufacturer of the medication as part of creating this article. All content is sourced from public references or the manufacturer.
