Frontline Products for Fleas and Ticks in Dogs and Cats

Medically Reviewed by Joshua Conrad, PharmD on October 21, 2024
Written by Kathleen Claussen, DVM
7 min read

The Frontline line of products (manufactured by Boehringer Ingelheim) includes topical products (products that are applied to the skin) for treating fleas, ticks, and chewing lice and repelling ticks and mosquitoes. Frontline products are approved by the Environmental Protection Agency (EPA) for the treatment and control of external parasites in dogs and cats depending on which product is being used.

All Frontline products for fleas and ticks contain fipronil. Fipronil is a phenylpyrazole antiparasitic agent indicated for the treatment of fleas, ticks, and chewing lice infestations in both dogs and cats. All Frontline products for fleas and ticks also contain other ingredients. These products include Frontline Plus, Frontline Gold, and Frontline Shield.

Frontline Plus for Dogs and Frontline Plus for Cats both contain fipronil and methoprene. Methoprene is an insect growth regulator that prevents immature fleas and mosquito eggs and larvae from growing into adults. Frontline Plus for Dogs is labeled for dogs at least 8 weeks old and weighing at least 5 pounds (2.2 kilograms). Frontline Plus for Cats is labeled for cats at least 8 weeks old and weighing at least 1.5 pounds (0.7 kilograms). 

Frontline Gold for Dogs and Frontline Gold for Cats both add pyriproxyfen to the fipronil/methoprene combination. Pyriproxyfen is a second-generation insect growth regulator that helps extend the activity to include flea eggs and larvae. This additional ingredient helps to prevent fleas from returning after they’ve been eliminated. Frontline Gold for Dogs is labeled for dogs at least 8 weeks old and weighing at least 5 pounds (2.2 kilograms). Frontline Gold for Cats is labeled for cats at least 8 weeks old and weighing at least 3 pounds (1.3 kilograms).

Frontline Shield is only for use in dogs. In addition to fipronil, it contains pyriproxyfen (described above) and permethrin. Permethrin is a synthetic neurotoxic pyrethroid that has activity against fleas, ticks, lice, and some mites. Permethrin cannot be used in cats since it can be lethal to them. Frontline Shield for Dogs treats fleas, ticks and chewing lice, as well as controls existing infestations and prevents fleas, ticks, and chewing lice from returning. Frontline Shield also aids in the control of certain mite infestations. Dogs and puppies need to be at least 9 weeks old and weigh at least 5 pounds (2.2 kilograms) to use Frontline Shield for Dogs.

Frontline products are usually well tolerated in animals. There is minimal risk for overdose, side effects, or drug interactions if used as labeled or as directed by your veterinarian.

Frontline products are available without a prescription. 

Most Frontline products are liquids that you apply to your pet’s skin between the shoulder blades once a month (every 30 days). Frontline Gold for Dogs is applied to the skin in a straight line from the base of the neck to the tip of the tail.

To apply Frontline Gold products to your pet, make sure the skin at the base of the pet’s head is dry and healthy. Using the appropriate tube of Frontline Gold, hold the tube upright and twist the applicator tip about one-half turn while pressing down to break the seal. For a dog, apply the contents of the tube in a straight line onto the skin along the back starting from the base of the neck to the tip of the tail. If you are treating a cat, part the hair and squeeze the entire contents of the tube directly onto the skin at the base of the neck in one spot. Do not touch that area until it is completely dry. Do not allow your cat or other pets in the household to groom (rub or lick) the application site for 24 hours. You may bathe your pet 48 hours after application.

To apply all other Frontline topical solutions (Frontline Plus and Frontline Shield products), remove one applicator tube that is the appropriate dose for the weight and animal type (dog or cat). Hold the tube upright with the foil side toward you and snap the tip (Frontline Plus) or cut along the marked line (Frontline Shield). Then part the pet’s hair till you can see the skin and squeeze the contents onto the skin in one spot between the shoulder blades. Do not touch that area until it is completely dry. Do not allow your pet or other pets in the household to groom (rub or lick) the application site until it dries.

Always follow your veterinarian’s directions for giving medicines to animals. Remember to tell your veterinarian about any medicines, vitamins, supplements, or herbal therapies that you are giving your pet. Talk to your veterinarian before stopping any pet medicines. 

  • Frontline products do not require a veterinary prescription to purchase.
  • Fipronil, methoprene, and pyriproxyfen are EPA-licensed to use in dogs and cats.
  • Frontline products remain effective even after swimming or bathing. Pets need to wait for 24 hours after Frontline product application to get wet.
  • All Frontline products kill fleas, flea eggs, flea larva, ticks, and chewing lice.
  • Frontline products do not expire.

You and your veterinarian should monitor your pet for signs that the medicine is working (for example, absence of live fleas and ticks), as well as for side effects of the medicine. There is no routine lab monitoring needed with Frontline products.

If Frontline Shield for Dogs is used for skin mite treatment, your veterinarian will monitor for improvement of symptoms (like hair loss and itching) and perform periodic skin tests. 

Do not use a Frontline product in an animal that is allergic to its ingredients. Do not use Frontline products in dogs or cats below the minimum age or weight on the product label. Do not allow your pet to ingest the medicine. Do not use cat products on dogs and do not use dog products on cats. Do not use Frontline products on rabbits or other small mammals. Use them with caution in medicated, frail, or older dogs and cats. Do not allow your pet or their housemates to lick the application site. Keep cats separated from dogs treated with Frontline products for 24 hours. Use Frontline products with caution in pregnant, nursing, or breeding animals.

Your pet should not be able to lick the site of application if using any of the Frontline topical solution products. Other pets may try to groom or lick at the application site, especially cats that clean each other. Try to prevent this from happening. If your pet ingests the medicine, they will usually have excessive salivation (drooling) and may even foam at the mouth. If your pet starts acting strangely, seek veterinary care.

Side effects are uncommon with Frontline products if they are used as directed on the label. Your pet may experience redness, itching, or other signs of discomfort at the application site. If any of these symptoms occur, bathe your pet with mild soap and rinse with large amounts of water. 

Other side effects with Frontline products may include vomiting or diarrhea (loose stool).

If you suspect that your pet is having a serious side effect or may have been overdosed, call your veterinary clinic immediately. If it is outside of regular office hours, you may contact a local emergency veterinary hospital or an animal poison control center. 

You can reach the ASPCA Animal Poison Control Center at 888-426-4435 or the Pet Poison Helpline at 855-764-7661.

Using multiple medicines can sometimes change how your pet’s medicines work or increase your pet’s risk for serious side effects. Always tell your veterinarian about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements that your pet is using.

There are no specific drug interactions noted with fipronil. It is unknown if there are drug interactions with the other medicines in Frontline products.

  • Keep Frontline products out of the reach of children.
  • Wash your hands with soap after handling Frontline products.
  • Do not handle Frontline products if you are allergic to any of the ingredients.
  • Avoid getting Frontline topical liquid in your eyes or on your skin and clothing.
  • Avoid contact with the area of application of the Frontline product on your pet until it is dry.

Frontline products are very well tolerated by animals and the risk of an overdose is low. If you are concerned your pet is having an adverse reaction or if you think your pet has gotten more medicine than intended, call your veterinarian or veterinary emergency clinic immediately.

If your pet misses a dose, give the dose when you remember and then restart the dosing interval from that date. Do not double the dose of the medicine. 

Store Frontline products in the original packaging in a cool, dry place. Do not use Frontline products near heat or an open flame. Do not contaminate food, feed, or water with Frontline products.