Picking the Best Flea and Tick Pill for Your Dog

Scritch, scritch, scritch. Your dog is scratching at himself—again. You thought you found and killed all those fleas and ticks that were biting him. But his scratching tells you otherwise.

We love our dogs. But we don’t love the hitchhikers they may bring into our homes. Fleas and ticks are more than just a nuisance. They carry diseases that can affect not only dogs, but humans and other pets in the family.

Thankfully, we have a lot of options when it comes to preventing infestations with these pesky pests. Flea pills, flea and tick pills, and topically applied repellents to keep our canine companions pest-free are readily available. In this article, we will cover the pills and chewables you can give your dog to treat and prevent flea and tick infestations.

Flea Pills for Dogs

There are three types of flea pills currently available for dogs. Two types quickly kill adult fleas and one type prevents flea larvae from developing into adult fleas.

Flea pills that quickly kill adult fleas are known as “quick kill” products. They work by binding to a neurotransmitter within the flea, leading to paralysis and death. Quick kill products begin killing fleas within 30 minutes of administering the pill to your dog. The active ingredients in these products include nitenpyram, imidacloprid, and spinosad.

Nitenpyram and imidacloprid are short duration products that only last 24 hours. They kill fleas that are actively biting your dog. Both products may be paired with a product that prevents flea infestations.

Nitenpyram

Nitenpyram is the active ingredient in Capstar and generic products like PetArmor CapAction. It is available for purchase without a prescription. Nitenpyram should not be used in puppies less than four weeks old or weighing less than two pounds.

Side effects of nitenpyram are rare but may include lethargy, vomiting, decreased appetite, diarrhea, or hyperactivity. Extremely rare side effects may include incoordination, seizures, excessive panting, hives, or hypersalivation. While these side effects are extremely rare, they may occur more often in puppies less than eight weeks old or in dogs that are unthrifty or in ill health.

Imidacloprid

Imidacloprid is the active ingredient in Advantus. It is available for purchase without a prescription. Imidacloprid should not be used in puppies less than ten weeks old. It should not be given to dogs or puppies weighing less than four pounds.

Side effects of imidacloprid are typically mild and may include vomiting, decreased appetite, soft stools, or a temporary change in gait. Rare but serious side effects include labored breathing, collapse, and pale gums. These three side effects are consistent with an allergic reaction to imidacloprid. Seek veterinary attention immediately if your dog experiences these side effects.

Spinosad

Spinosad is a quick kill, long duration product that lasts 30 days. Like nitenpyram and imidacloprid, it kills fleas that are actively biting your dog. Spinosad can also treat and prevent flea infestations because of its long duration of action. It kills newly hatched fleas that feed on your dog before they have a chance to lay eggs.

Spinosad is the active ingredient in Comfortis and Trifexis. A prescription from your veterinarian is required to purchase products containing spinosad. Dogs and puppies should weigh at least five pounds to receive Comfortis or Trifexis.

Comfortis contains only spinosad. It should not be used in puppies less than 14 weeks old. Trifexis contains spinosad and milbemycin oxime. Milbemycin oxime is a medication used to prevent heartworm disease and treat dogs infected with the intestinal parasites roundworm, hookworm, or whipworm. Trifexis should not be used in puppies less than 8 weeks old.

Lufenuron

Lufenuron is an insect growth regulator (IGR) that interferes with the development of flea larvae. Female fleas lay eggs in your dog’s fur after mating with male fleas. Most of these eggs will fall from your dog’s fur and land in the places your dog spends most of his time. This may include his bed, the couch, a favorite chair, or your bed.

Larvae hatch from eggs and begin the first of three molts before they pupate. Each molt requires building a new exoskeleton. A key component of this exoskeleton is chitin. Lufenuron inhibits chitin formation and prevents the development of a strong exoskeleton. Flea larvae that have an exoskeleton weakened by lufenuron die.

It is important to note that lufenuron does not kill adult fleas. It only prevents the development of flea larvae into adults. Lufenuron is often paired with a flea adulticide taken orally or applied topically to your dog to completely break the flea life cycle.

Lufenuron is one of the active ingredients in Sentinel and Sentinel Spectrum. Both products also contain milbemycin oxime. Sentinel Spectrum contains praziquantel for the treatment of tapeworm infections. A prescription from your veterinarian is required for the purchase of both products.

Dogs and puppies should weigh at least two pounds to receive Sentinel or Sentinel Spectrum. Sentinel should not be used in puppies less than four weeks old. Puppies should be at least six weeks old to receive Sentinel Spectrum.

Side effects of lufenuron are rare but may include vomiting, decreased appetite, or lethargy. Allergic reactions to lufenuron are extremely rare. If your dog experiences labored breathing or hives after receiving a product containing lufenuron, seek veterinary attention immediately.

Flea and Tick Pills for Dogs

There is one type of flea and tick pill currently available on the market. This type is known as an isoxazoline (pronounced eye-sock-SAH-zuh-leen) drug. Isoxazolines bind to a neuroreceptor in fleas, ticks, and mites, causing paralysis followed by death of these insects and acarids.

There are currently four products available in the isoxazoline drug class. These products include afoxolaner, sarolaner, fluralaner, and lotilaner. All of these products begin killing fleas and ticks that are actively biting your dog within several hours. They achieve a nearly 100% flea kill rate within 12 hours of administration and a nearly 100% tick kill rate within 24-48 hours of administration.

There are two primary goals of these products. The first is to kill adult fleas before they can lay eggs in your dog’s environment. The second is to kill ticks before they have an opportunity to transmit bacteria to your dog that can cause tick-borne diseases. These diseases include Lyme disease, anaplasmosis, ehrlichiosis, and Rocky Mountain Spotted Fever.

Afoxolaner is the active ingredient in Nexgard and Nexgard Plus. Fluralaner is the active ingredient in Bravecto chews and Bravecto 1-month chews. Simparica and Simparica Trio contain sarolaner. Lotilaner is the active ingredient in Credelio and Credelio Quattro.

All four products require a veterinary prescription. Not all of these products kill all species of ticks or last the same amount of time. See the table below for more on the differences between these products and to determine which one is best for your dog based on age, weight, disease risk and where you live.

The Best Flea and Tick Pills for Dogs

Potential Side Effects of Isoxazolines

Side effects of isoxazolines are rare but may include vomiting, diarrhea, lethargy, or decreased appetite.

The Food and Drug Administration (FDA) issued an alert in 2018 that isoxazolines have the potential to cause muscle tremors, ataxia (wobbly gait), or seizures in dogs and cats. Talk to your veterinarian about alternative flea/tick preventatives if your dog has a history of seizures or has had a seizure following administration of an isoxazoline.

Natural Products That Repel Fleas and Ticks

A simple internet search for natural flea and tick pills that repel these pests will return an abundance of solutions, including brewer’s yeast, garlic, apple cider vinegar, and coconut oil. The thought is that these compounds will cause an odor to emanate from your dog that fleas and ticks find undesirable. But do these natural remedies actually work?

The short answer is no, these compounds and the products that contain them will not repel fleas or ticks. Fleas and ticks seek out a host by sensing vibration and movement, body heat, and exhaled carbon dioxide. Ticks are also able to detect moisture emanating from a host. Clearly, fleas and ticks have a sophisticated sensory system. But appreciating odors is not a tool in their tool box.

Giving your dog garlic, apple cider vinegar, or coconut oil could potentially harm your dog. Garlic contains organosulfur compounds that may cause oxidative damage to red blood cells. Red blood cells that have undergone oxidative damage become fragile and burst. This results in a condition called hemolytic anemia. Symptoms of hemolytic anemia include sudden onset of lethargy, weakness, difficulty breathing, and pale gums.

Apple cider vinegar is acidic with a pH of 3.0-5.5. This acidity can cause gastrointestinal upset, including vomiting and decreased appetite. Coconut oil is high in saturated fat and can increase the risk of developing pancreatitis and diarrhea. Rapid weight gain is another potential side effect of giving your dog too much coconut oil.

The Importance of Flea and Tick Prevention

Preventing flea and tick infestations is a key part of keeping your dog comfortable and at his best. It is also important for the prevention of flea- and tick-borne disease, not just for your dog but for all members of your family. Talk to your veterinarian about which high-quality, proven flea pill or flea and tick pill is right for your dog.