Written By hannah hollinger
Published: 08/10/2020Updated: 08/30/2021
NexGard for Dogs | Wag!
NexGard is a popular flea and tick treatment. This flavored chewable is an effective alternative to topical spot treatments and is easy to administer. NexGard contains afoxolaner, a fast-acting insecticide that works by attacking the parasite’s central nervous system.


NexGard is a beef-flavored chewable tablet that comes in the following dosage strengths based on your dog’s size:

  • 4 to 10 lbs. — 11.3 mg of afoxolaner

  • 10 to 24 lbs. — 28.3 mg

  • 24 to 60 lbs. — 68 mg

  • 60 to 121 lbs. — 136 mg

  • >121 lbs. — 1.14 mg/lb

NexGard is safe to use in puppies 8 weeks or older weighing 4 lbs. or more.

Dosage instructions

Since NexGard is beef-flavored, you’ll likely have less trouble administering it compared to other medications. If your dog is a little stubborn, you can try giving it with food or a treat. If your dog vomits or loses all or part of the dose within 2 hours of administration, give another full dose. Readminister a NexGard chewable once every 30 days.


NexGard works quickly, entering the bloodstream within 30 minutes of ingestion. It starts killing fleas within 4 hours and ticks within 12 hours. One study found that afoxolaner kills existing fleas within 2 to 6 hours and maintains an average mortality rate of between 97.6% to 100% for 3 weeks after treatment.

Active ingredients in NexGard for Dogs

Afoxolaner is the active ingredient in NexGard for dogs. In addition to killing fleas and ticks, it also treats certain types of mange. 

Side effects

Occurring in just 4% of treated dogs, side effects associated with NexGard are rare and typically mild. Most often, adverse effects indicate an allergic reaction. The most common side effects include:

  • Vomiting

  • Diarrhea

  • Dry skin

  • Lethargy

  • Weight loss

  • Excessive scratching

  • Loss of appetite

If you notice any serious side effects, contact your vet.


NexGard may not be safe for pregnant or lactating dogs. The FDA issued a warning in 2018 regarding neurological side effects associated with drugs in the isoxazoline class, including NexGard. Some pets treated with NexGard and similar drugs experienced muscle spasms, loss of muscle control, and seizures. Dogs with a history of seizures should use this medication with caution.

However, NexGard is FDA-approved, and the FDA is monitoring new developments closely. If you notice any serious adverse effects or have any concern about the drug’s safety, contact your veterinarian immediately.

Drug interactions

No drug interactions with NexGard have been identified at the time of writing. Be sure to let your vet know if your dog is taking any prescription or over-the-counter medications before starting NexGard.

Allergic reactions and sensitivity

Allergic reactions and sensitivity to NexGard are rare. Side effects may indicate an allergic reaction.

Frequently asked questions

Do I need a prescription for NexGard?

Yes, NexGard is a prescription-only drug.

I’ve given my dog NexGard, so why do they still have fleas?

NexGard works by poisoning any fleas that bite your dog. You’ll also need to treat the environment, including your home and yard, as well as your dog for maximum protection.

Why are fleas so noticeable after using NexGard?

Because afoxolaner overstimulates the fleas’ nervous system, you’ll notice fleas come to the surface of your dog’s coat. This indicates that NexGard is working.

What should I do if I miss a dose?

To keep your dog protected from parasites and avoid treatment gaps, it’s important to adhere to the dosing schedule. However, if you do miss a dose, give it as soon as you remember. Then, adjust the dosing schedule so that the next dose is 30 days after the new dose. Never administer two doses at once or give extra doses. Setting a reminder can help you remember.

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