NexGard ® (afoxolaner) Chewables

CAUTION: Federal law restricts this drug to use by or on the order of a licensed veterinarian.

NexGard^® (afoxolaner) is available in four sizes of beef-flavored, soft chewables for oral administration to dogs and puppies according to their weight. Each chewable is formulated to provide a minimum afoxolaner dosage of 1.14 mg/lb (2.5 mg/kg). Afoxolaner has the chemical composition 1-Naphthalenecarboxamide, 4-[5-[3-chloro-5-(trifluoromethyl)-phenyl]-4, 5-dihydro-5-(trifluoromethyl)-3-isoxazolyl]-N-[2-oxo-2-[(2,2,2-trifluoroethyl)amino]ethyl.

NexGard^® kills adult fleas and is indicated for the treatment and prevention of flea infestations (Ctenocephalides felis), and the treatment and control of Ixodes scapularis (black-legged tick), Dermacentor variabilis (American dog tick), Amblyomma americanum (lone star tick), Amblyomma maculatum (Gulf Coast tick), Rhipicephalus sanguineus (brown dog tick), and Haemaphysalis longicornis (longhorned tick) infestations in dogs and puppies 8 weeks of age and older, weighing 4 pounds of body weight or greater, for one month. NexGard^® is indicated for the prevention of Borrelia burgdorferi infections as a direct result of killing lxodes scapularis vector ticks.

NexGard^® is given orally once a month, at the minimum dosage of 1.14 mg/lb (2.5 mg/kg).

There are no known contraindications for the use of NexGard^®.

Not for use in humans. Keep this and all drugs out of the reach of children. In case of accidental ingestion, contact a physician immediately.

Keep NexGard^® in a secure location out of reach of dogs, cats, and other animals to prevent accidental ingestion or overdose.

Afoxolaner is a member of the isoxazoline class. This class has been associated with neurologic adverse reactions including tremors, ataxia, and seizures. Seizures have been reported in dogs receiving isoxazoline class drugs, even in dogs without a history of seizures. Use with caution in dogs with a history of seizures or neurologic disorders.

The safe use of NexGard^® in breeding, pregnant or lactating dogs has not been evaluated.

In a well-controlled US field study, which included a total of 333 households and 615 treated dogs (415 administered afoxolaner; 200 administered active control), no serious adverse reactions were observed with NexGard^®.

Over the 90-day study period, all observations of potential adverse reactions were recorded. The most frequent reactions reported at an incidence of > 1% within any of the three months of observations are presented in the following table. The most frequently reported adverse reaction was vomiting. The occurrence of vomiting was generally self-limiting and of short duration and tended to decrease with subsequent doses in both groups. Five treated dogs experienced anorexia during the study, and two of those dogs experienced anorexia with the first dose but not subsequent doses.

In the US field study, one dog with a history of seizures experienced a seizure on the same day after receiving the first dose and on the same day after receiving the second dose of NexGard^®. This dog experienced a third seizure one week after receiving the third dose. The dog remained enrolled and completed the study. Another dog with a history of seizures had a seizure 19 days after the third dose of NexGard^®. The dog remained enrolled and completed the study. A third dog with a history of seizures received NexGard^® and experienced no seizures throughout the study.

In a second US field safety and effectiveness study, NexGard^® was administered to 130 dogs with fleas. Adverse reactions included pruritus, diarrhea (with or without blood), vomiting, anorexia, and lethargy.

The following adverse events are based on post-approval adverse drug experience reporting. Not all adverse events are reported to FDA/CVM. It is not always possible to reliably estimate the adverse event frequency or establish a causal relationship to product exposure using these data.

The following adverse events reported for dogs are listed in decreasing order of reporting frequency for NexGard^®:

Vomiting, pruritus, lethargy, diarrhea (with and without blood), anorexia, seizure, hyperactivity/restlessness, panting, erythema, ataxia, dermatitis (including rash, papules), allergic reactions (including hives, swelling), and tremors.

Contact Information:

For a copy of the Safety Data Sheet (SDS) or to report suspected adverse drug events, contact Boehringer Ingelheim Animal Health USA Inc. at 1-888-637-4251 or www.nexgardforpets.com.

For additional information about adverse drug experience reporting for animal drugs, contact FDA at 1-888-FDA-VETS or www.fda.gov/reportanimalae.

Afoxolaner is a member of the isoxazoline family, shown to bind at a binding site to inhibit insect and acarine ligand-gated chloride channels, in particular those gated by the neurotransmitter gamma-aminobutyric acid (GABA), thereby blocking pre- and post-synaptic transfer of chloride ions across cell membranes. Prolonged afoxolaner-induced hyperexcitation results in uncontrolled activity of the central nervous system and death of insects and acarines. The selective toxicity of afoxolaner between insects and acarines and mammals may be inferred by the differential sensitivity of the insects and acarines' GABA receptors versus mammalian GABA receptors.

In a well-controlled laboratory study, NexGard^® began to kill fleas four hours after initial administration and demonstrated >99% effectiveness at eight hours. In a separate well-controlled laboratory study, NexGard^® demonstrated 100% effectiveness against adult fleas 24 hours post-infestation for 35 days, and was ≥93% effective at 12 hours post-infestation through Day 21, and on Day 35. On Day 28, NexGard^® was 81.1% effective 12 hours post-infestation. Dogs in both the treated and control groups that were infested with fleas on Day -1 generated flea eggs at 12- and 24-hours post-treatment (0-11 eggs and 1-17 eggs in the NexGard^® treated dogs, and 4-90 eggs and 0-118 eggs in the control dogs, at 12- and 24-hours, respectively). At subsequent evaluations post-infestation, fleas from dogs in the treated group were essentially unable to produce any eggs (0-1 eggs) while fleas from dogs in the control group continued to produce eggs (1-141 eggs).

In a 90-day US field study conducted in households with existing flea infestations of varying severity, the effectiveness of NexGard^® against fleas on the Day 30, 60 and 90 visits compared with baseline was 98.0%, 99.7%, and 99.9%, respectively. In a second 90-day US field study, the effectiveness of NexGard^® against fleas on the Day 30, 60 and 90 visits compared with baseline was 97.5%, 99.7%, and 99.9%, respectively. Dogs in the second study with signs of Flea Allergy Dermatitis (FAD) showed improvement in erythema, alopecia, papules, scales, crusts, and excoriation following treatment, as a direct result of eliminating fleas.

Collectively, the data from these studies (two laboratory and two field) demonstrate that NexGard^® kills fleas before they can lay eggs, thus preventing subsequent flea infestations after the start of treatment of existing flea infestations.

In well-controlled laboratory studies, NexGard^® demonstrated >97% effectiveness against Dermacentor variabilis, >94% effectiveness against Ixodes scapularis, and >93% effectiveness against Rhipicephalus sanguineus, 48 hours post-infestation for 30 days. At 72 hours post-infestation, NexGard^® demonstrated >97% effectiveness against Amblyomma americanum for 30 days, ≥98.5% effectiveness against Haemaphysalis longicornis, and ≥97% effectiveness against Amblyomma maculatum for 31 days. In two separate, well-controlled laboratory studies, NexGard^® was effective at preventing Borrelia burgdorferi infections after dogs were infested with Ixodes scapularis vector ticks 28 days post-treatment.

In a margin of safety study, NexGard^® was administered orally to 8 to 9-week-old Beagle puppies at 1, 3, and 5 times the maximum exposure dose (6.3 mg/kg) for three treatments every 28 days, followed by three treatments every 14 days, for a total of six treatments. Dogs in the control group were sham-dosed. There were no clinically-relevant effects related to treatment on physical examination, body weight, food consumption, clinical pathology (hematology, clinical chemistries, or coagulation tests), gross pathology, histopathology or organ weights. Vomiting occurred throughout the study, with a similar incidence in the treated and control groups, including one dog in the 5X group that vomited four hours after treatment.

In two well-controlled field studies, NexGard^® was used concomitantly with other medications, such as vaccines, anthelmintics, antibiotics (including topicals), steroids, NSAIDs, anesthetics, and antihistamines. No adverse reactions were observed from the concomitant use of NexGard^® with other medications.

Store at or below 30°C (86°F) with excursions permitted up to 40°C (104°F).

NexGard^® is available in four sizes of beef-flavored soft chewables: 11.3, 28.3, 68 or 136 mg afoxolaner. Each chewable size is available in color-coded packages of 1, 3 or 6 beef-flavored chewables.

Approved by FDA under NADA # 141-406

Marketed by: Boehringer Ingelheim Animal Health USA Inc., Duluth, GA 30096

NEXGARD^® is a registered trademark of Boehringer Ingelheim Animal Health France, used under license.
©2025 Boehringer Ingelheim Animal Health USA Inc. All rights reserved.

156090-004
Rev. 12/2025

NexGard
(afoxolaner)
Chewables
For oral use in dogs

Original EUA Authorized Date: 02/18/2026

Emergency Use Authorization for NexGard (afoxolaner) chewables for NWS

The U.S. Food and Drug Administration (FDA) has issued an Emergency Use Authorization (EUA) for the emergency use of the approved product NexGard (afoxolaner) for the treatment of infestations caused by NWS (Cochliomyia hominivorax) larvae (myiasis) in dogs and puppies. NexGard is not approved for this use.

NexGard (afoxolaner) (NADA 141-406) is approved for other uses in dogs and puppies.¹

Limitations of Authorized Use

NexGard (afoxolaner) is authorized for this use only for the duration of the declaration that circumstances exist justifying the authorization of the emergency use of NexGard (afoxolaner) under section 564(b)(1) of the Federal Food, Drug, and Cosmetic Act (FD&C Act), 21 U.S.C. § 360bbb-3(b)(1), unless the declaration is terminated or the authorization is revoked sooner.

Justification for Emergency Use of Animal Drugs for NWS

The Secretary of the U.S. Department of Health and Human Services (HHS) has:

• determined that there is a significant potential for a public health emergency that has a significant potential to affect national security or the health and security of United States citizens living abroad and that involves NWS (Cochliomyia hominivorax); and
• declared that circumstances exist justifying the authorization of emergency use of animal drugs to treat or prevent NWS myiasis in animals.²

An EUA is an FDA authorization for the emergency use of an unapproved product or unapproved use of an approved product (i.e., drug, biological product, or device) in the United States under certain circumstances declared by the Secretary of HHS to justify emergency use authorization, including, among others, a determination that there is a public health emergency or a significant potential for a public health emergency that may affect national security and that involves a biological agent.³

Criteria for issuing an EUA include:

• The biological agent can cause a serious or life-threatening disease or condition;
• Based on the totality of available scientific evidence (including data from adequate and well-controlled clinical trials, if available), it is reasonable to believe that:
  • othe product may be effective in diagnosing, preventing, or treating the serious or life-threatening disease or condition; and
  • othe known and potential benefits of the product - when used to diagnose, prevent, or treat such disease or condition - outweigh the known and potential risks of the product; and
• There is no adequate, approved, and available alternative to the product for diagnosing, preventing, or treating the serious or life-threatening disease or condition.⁴

Caution: Federal law restricts this drug to use by or on the order of a licensed veterinarian.

Product Description

Refer to the NexGard package insert for full Product Description information.

Dosage and Administration

NexGard is given orally at the minimum dosage of 1.14 mg/lb (2.5 mg/kg). NexGard should be used in conjunction with the mechanical removal of larvae (live and dead) remaining in the wound after treatment (see Precautions).

Dosing Schedule:

NexGard can be administered with or without food.

If suspected that any of the dose has been lost or if vomiting occurs within two hours of administration, redose with another full dose.

NexGard is not available in scored tablets. The effectiveness of the administration of less than full tablets has not been evaluated.

Risk-Benefit Consideration for Dogs on Other Isoxazolines:
If a dog is currently receiving another isoxazoline product for routine ectoparasite control, veterinarians should consider administering NexGard to dogs diagnosed with NWS larvae based on a risk-benefit assessment and the emergency nature of the treatment of NWS infestation.

Information Supporting Emergency Use Authorization

Based on the totality of scientific evidence available to FDA, including data from published scientific literature, it is reasonable to believe that NexGard (afoxolaner) chewables may be effective for the treatment of infestations caused by NWS (Cochliomyia hominivorax) larvae (myiasis) in dogs and puppies, and when used under the conditions described in the authorization, the known and potential benefits of NexGard (afoxolaner) chewables outweigh the known and potential risks.

• 1. A study conducted in Brazil over a 13-month period by Cutolo et al.⁵, evaluated 14 privately owned dogs naturally infested with C. hominivorax larvae. After diagnosis of myiasis by observation of larvae in a wound, all dogs were administered a single dose of NexGard (afoxolaner) orally at the recommended labelled dose for the approved indications (2.5 mg afoxolaner/kg body weight). The study did not include a control group. At 24 hours post-treatment, the lesions were evaluated, and all remaining larvae were mechanically removed from the wound. Expelled larvae were collected from the ground or around the dog. All larvae (expelled and mechanically removed) were dead 24 hours post-treatment. Larvicidal effectiveness was 100% at 24 hours post-treatment.
• 
  Three dogs living in the same household developed C. hominivorax myiasis over a 41-day period. The first dog developed myiasis and was treated with NexGard (afoxolaner). The dog continued to live in the home environment while the wound was healing. Twenty-three days after the first dog was diagnosed and treated, the second dog was diagnosed with C. hominivorax myiasis, indicating active female fly activity in the environment. The second dog was treated with NexGard (afoxolaner). Both dogs were reexamined on the same day (33 days post-treatment for the first dog, 11 days post-treatment for the second dog). Neither dog had larval infestations. Eighteen days after the second dog was treated (41 days post-treatment for the first dog), the third dog was diagnosed with C. hominivorax myiasis and treated with NexGard (afoxolaner). Three days after the third dog was treated (44 days post-treatment for the first dog, 21 days post-treatment for the second dog), all the dogs were reexamined. No dog had larval infestations.
• 
  One dog in the study presented with an extensive wound on the back of its neck that was reported to be repeatedly infested with C. hominivorax larvae. Twenty-nine days after diagnosis of myiasis and treatment with NexGard (afoxolaner), the lesion was almost completely healed, and no larval infestations were reported within that time.
• 
  No adverse events were recorded.
• 
  The study supports that NexGard may be effective for the treatment of infestations caused by NWS (Cochliomyia hominivorax) larvae (myiasis). More information is needed to evaluate the use of NexGard for the prevention of infestations caused by NWS (Cochliomyia hominivorax) larvae (myiasis).
• 
  2. A study conducted by Han et al.⁶ evaluated 40 privately owned dogs with naturally occurring cutaneous myiasis; 8 dogs were treated with NexGard (range 2.7 to 6.8 mg/kg). All screwworms were presumed to be Chrysomya bezziana (Old World screwworm (OWS)), but morphological confirmation was not performed. Dogs were randomized to five treatment groups, eight dogs per group, and dosed orally at doses recommended by the manufacturer for treatment of their approved target parasite species. Dogs were evaluated hourly for 7 hours and again 24-hours post-treatment. Observations were recorded as no observed effect, partial paresis/death of some larvae and its expulsion, and complete death of all larvae. Dogs with live larvae present at 24 hours were then treated with topical organophosphates. The NexGard treatment group had live larvae 7 hours post-treatment but achieved complete larval kill in all dogs 24-hours post-treatment. The mean speed of onset was 4 hours and the mean time for complete eradication of larvae was 12 hours.

There are limitations of the data supporting the benefits of NexGard for treatment of infestations caused by NWS in dogs. The Cutolo et al. study was conducted in a limited population of 14 naturally infested dogs in Brazil. The lack of a control group confounds the ability to define a pure treatment effect. The Han et al. study was conducted with presumptive OWS infestations. The comparability of OWS and NWS is unknown.

The available clinical data supporting the effectiveness of NexGard against C. hominivorax larvae, along with the established safety profile, support the potential benefit of NexGard in the authorized patient population for treatment of infestations caused by NWS larvae.

Contraindications

There are no known contraindications for the use of NexGard.

Warnings

Not for use in humans. Keep this and all drugs out of the reach of children. In case of accidental ingestion, contact a physician immediately.

Keep NexGard in a secure location out of reach of dogs, cats, and other animals to prevent accidental ingestion or overdose.

To obtain a Safety Data Sheet(s), contact Boehringer Ingelheim Animal Health USA Inc. at 1-888-637-4251 or www.nexgardforpets.com.

Precautions

Afoxolaner is a member of the isoxazoline class. This class has been associated with neurologic adverse reactions including tremors, ataxia, and seizures. Seizures have been reported in dogs receiving isoxazoline class drugs, even in dogs without a history of seizures. Use with caution in dogs with a history of seizures or neurologic disorders.

The safe use of NexGard in breeding, pregnant or lactating dogs has not been evaluated.

The safety of NexGard has not been evaluated in dogs less than 8 weeks of age or less than 4 lbs body weight.

Effective treatment of NWS myiasis includes removal of the larvae. Appropriate wound care, including surgical debridement as needed and pain management, should be implemented.⁷

Adverse Reactions

Refer to the package insert for full prescribing information, including Animal Safety, Adverse Reactions and Post-Approval Experience.

As described in the Letter of Authorization, veterinary facilities and veterinarians must report all SERIOUS ADVERSE EVENTS* potentially related to NexGard (afoxolaner) chewables use under this EUA (1) by contacting Boehringer Ingelheim Animal Health USA Inc. at 1-888-637-4251, (2) by downloading and submitting Form FDA 1932a available at www.fda.gov/reportanimalae, or (3) contacting FDA at 1-888-FDA-VETS to request this form.

When reporting adverse events on Form FDA 1932a, include the following elements when applicable and/or available:

• Patient demographics (e.g., age, species and breed, sex, weight)
• The statement “NexGard (afoxolaner) use for NWS under an EUA” under the “Adverse Event/Product Problem/Product Use Error” heading
• Information about the serious adverse event (e.g., signs and symptoms, test/laboratory data, timing of drug administration in relation to the occurrence of the event, duration of the event, treatment required to mitigate the event, evidence of event improvement/disappearance after stopping/reducing the dosage, evidence of reappearance after reintroduction, clinical outcomes)
• Patient’s pre-existing medical conditions and use of concomitant products
• Information about the product (e.g., dosage, route of administration, lot number)

*Serious adverse events are defined as:

• Death
• A life-threatening adverse event
• An event that causes an abortion, stillbirth, or infertility
• A congenital anomaly or birth defect in offspring of treated animals
• A prolonged or permanent disability (e.g., persistent or significant incapacity or disruption of normal life functions)
• An event that requires professional intervention (e.g., important medical events that may require a medical/surgical intervention to prevent a death, life-threatening event, hospitalization, disability)

Reporting of lack of effectiveness, nonserious adverse events, or product quality defects is strongly encouraged via the mechanisms and including the information identified above for SERIOUS ADVERSE EVENTS.

Additional Information for Veterinarians

Veterinary facilities and veterinarians will ensure that they are aware of and adhere to the terms of the Letter of Authorization. Fact Sheets will be made available to veterinarians.

Veterinary facilities and veterinarians will ensure that the client is aware that the drug is authorized for emergency use, but not approved, for the treatment of NWS myiasis and advise the client of the risks, benefits, and any alternatives.

Veterinary facilities will maintain health records that include the following information: client name, patient name, patient age, disease manifestation, number of doses prescribed or administered per patient, lot number prescribed or administered, and other drugs co-administered. The records shall be maintained in a manner that allows veterinary facilities to identify in a reasonable time which patients received drugs subject to this EUA.

Veterinary facilities will maintain any health records for the authorized use in this Letter of Authorization for at least two years following the termination of the declaration or revocation of the authorization, or until notified by HHS, or FDA, whichever is sooner. Such records will be made available to Boehringer Ingelheim Animal Health USA Inc., HHS, and FDA for inspection upon request.

Information for Client (e.g., Animal Owner)

The lifecycle for C. hominivorax is as short as 21 days and wounds can be rapidly infested. Proper wound care and management practices are essential for preventing NWS myiasis. Dogs may become reinfested following treatment.

Clients should be advised that:

• Gloves should be worn if cleaning the wound, or the dog’s bedding, or disposing of larvae.
• Dogs should be housed to prevent exposure to NWS flies until wounds have fully healed.
• Live larvae may exit the wound and be deposited on bedding or areas where the dog sits or lies after treatment.
• If expelled larvae are seen, owners should place the larvae in a sealed container with rubbing alcohol.
• If there is worsening of the wound, the owner should contact the veterinarian.

How Supplied

NexGard is available in four sizes of beef-flavored soft chewables: 11.3, 28.3, 68, or 136 mg afoxolaner. Each chewable size is available in color-coded packages of 1, 3, or 6 beef-flavored chewables.

Storage Information

Store at or below 30°C (86°F) with excursions permitted up to 40°C (104°F).

Marketed by: Boehringer Ingelheim Animal Health USA Inc. Duluth, GA 30096

Rev. date 02/2026

¹ NexGard kills adult fleas and is indicated for the treatment and prevention of flea infestations (Ctenocephalides felis), and the treatment and control of Ixodes scapularis (black-legged tick), Dermacentor variabilis (American dog tick), Amblyomma americanum (lone star tick), Rhipicephalus sanguineus (brown dog tick), and Haemaphysalis longicornis (longhorned tick) infestations in dogs and puppies 8 weeks of age and older, weighing 4 pounds of body weight or greater, for one month. NexGard is indicated for the prevention of Borrelia burgdorferi infections as a direct result of killing Ixodes scapularis vector ticks.

² See U.S. Department of Health and Human Services, Declaration of Emergency Pursuant to the Federal Food, Drug, and Cosmetic Act for New World Screwworm, August 20, 2025: www.federalregister.gov/documents/2025/08/20/2025-15918/declaration-of-emergency-pursuant-to-the-federal-food-drug-and-cosmetic-act-for-new-world-screwworm

³ Emergency Use Authorization of Medical Products and Related Authorities | FDA (www.fda.gov/regulatory-information/search-fda-guidance-documents/emergency-use-authorization-medical-products-and-related-authorities)

⁴ www.fda.gov/emergency-preparedness-and-response/mcm-legal-regulatory-and-policy-framework/emergency-use-authorization

⁵ Cutolo, A.A., Perier, N., Menz, I., Thyssen, P., Silva, F.O., & Beugnet, F. (2021). Effectiveness of afoxolaner (NexGard^®) on the treatment of myiasis caused by the New World screwworm fly Cochliomyia hominivorax (Diptera: Calliphoridae) in naturally infested dogs. Veterinary parasitology, regional studies and reports, 24, 100569.

⁶ Han, H.S., Chen, C., Schievano, C. and Noli, C. (2018). The comparative efficacy of afoxolaner, spinosad, milbemycin, spinosad plus milbemycin, and nitenpyram for the treatment of canine cutaneous myiasis. Veterinary dermatology. 10.1111/vde.12548.

⁷ Cutolo et al, Effectiveness of afoxolaner (NexGard^®) on the treatment of myiasis caused by the New World screwworm fly Cochliomyia hominivorax (Diptera: Calliphoridae) in naturally infested dogs. Vet Parasitol Reg Stud Rep. 2021:24:100569