NexGard for Dogs: Uses, Cost & Side Effects

This information is for educational purposes only. Never give your pet any medication without your veterinarian's guidance. Dosing, frequency, and safety depend on your pet's specific health profile.

NexGard is a prescription monthly chewable for dogs that contains afoxolaner, an isoxazoline parasite-control medication. It is designed to kill adult fleas and control several tick species for one month at a time. In the United States, it is labeled for dogs and puppies 8 weeks of age and older that weigh at least 4 pounds.

Because it is a flavored oral chew, many pet parents find it easier than a topical product. It can be given with or without food, but your vet may suggest giving it with a meal if your dog has a sensitive stomach. NexGard is for dogs only. Even though the skeleton includes cats in the species list, the standard NexGard chewable discussed in this article should not be shared across species.

NexGard is different from combination products such as NexGard PLUS or NexGard Spectra. Standard NexGard focuses on fleas and ticks. It does not provide heartworm prevention or intestinal parasite coverage, so some dogs need a separate medication plan depending on lifestyle, region, and parasite risk.

NexGard is FDA-approved for the treatment and prevention of flea infestations and for the treatment and control of ticks for one month. Current US labeling includes black-legged ticks, American dog ticks, lone star ticks, brown dog ticks, and longhorned ticks. The label also notes prevention of Borrelia burgdorferi infection as a direct result of killing black-legged ticks, which helps lower Lyme disease risk.

In practice, your vet may recommend NexGard when a dog needs reliable monthly flea and tick control, especially if topical products are hard to apply or wash off too easily. It may also help dogs with flea allergy dermatitis because removing fleas can improve itching, redness, crusting, and hair loss tied to flea exposure.

Some veterinarians also use afoxolaner extra-label for conditions such as demodectic mange, sarcoptic mange, or occasionally ear mites. Extra-label use is common in veterinary medicine, but it should always be guided by your vet because the dosing plan, follow-up, and expected response can differ from routine flea-and-tick prevention.

NexGard is given by mouth once every 30 days. The labeled minimum dose is 2.5 mg/kg (1.14 mg/lb) of afoxolaner. The chew size is chosen by your dog's body weight, and the FDA dosing schedule includes: 4 to 10 pounds = 11.3 mg, 10.1 to 24 pounds = 28.3 mg, 24.1 to 60 pounds = 68 mg, and 60.1 to 121 pounds = 136 mg. Dogs over 121 pounds are typically given the appropriate combination of chew sizes as directed by your vet.

It is important to use the correct weight range and make sure your dog eats the full chew. If part of the dose is lost, spit out, or vomited soon after dosing, call your vet for guidance before repeating it. If you miss a monthly dose, give it when you remember and then resume the regular monthly schedule.

Do not split chews unless your vet specifically instructs you to do so. Puppies grow quickly, and adult dogs can move between weight boxes over time, so it is smart to confirm your dog's current weight before refills. If your dog has a history of seizures, neurologic disease, or takes several medications, ask your vet whether this is the right parasite-control option for your household.

Many dogs take NexGard without major problems, but side effects can happen. Commonly reported effects include vomiting, diarrhea, dry or flaky skin, lethargy, and decreased appetite. Mild stomach upset may pass on its own, but persistent vomiting, marked tiredness, or refusal to eat should prompt a call to your vet.

Like other drugs in the isoxazoline class, NexGard carries a neurologic precaution. Tremors, ataxia, and seizures have been reported, including in some dogs without a prior seizure history. The overall risk appears low, but it matters more in dogs with known epilepsy, previous unexplained neurologic episodes, or other conditions that lower the seizure threshold.

Allergic-type reactions are also possible, though less common. Watch for facial swelling, hives, intense itching, or sudden collapse after dosing. If you notice those signs, or if your dog has a seizure, severe weakness, trouble walking, or repeated vomiting, see your vet immediately.

There are no widely recognized routine drug interactions listed as contraindications for NexGard, and the label states there are no known contraindications. Even so, that does not mean every combination is ideal for every dog. Your vet should review all prescription medications, preventives, supplements, and over-the-counter products before starting any new parasite-control plan.

Extra caution is reasonable when NexGard is used alongside other medications that may affect the nervous system, or in dogs with a history of seizures. It is also worth reviewing whether your dog is already receiving another flea, tick, or mite product so your vet can avoid unnecessary overlap.

If your dog needs broader parasite coverage, your vet may recommend a coordinated plan using NexGard with a separate heartworm preventive, or may suggest a combination product instead. The safest approach is not to stack products on your own. Bring a full medication list, including supplements and preventives, to every visit.