Pet Drug Reports

Afoxolaner (NexGard)adverse event reports that FDA received

Active ingredient

The name in brackets is a brand name with this active ingredient.

The openFDA records give the value "MSK" for the brand name and for the manufacturer name of each drug. FDA says that MSK means "masked". So the site cannot count a report for a brand.

Read this first. FDA says this about the data:

An API dataset query result cannot be used to estimate the risk associated with the product or compare one drug or device product with another. When looking at the results, be aware that there is no certainty that the reported drug or device caused the adverse event. This dataset should not be the sole source of information for clinical decision-making or other assumptions about the safety or effectiveness of a product. The adverse event may have been related to an underlying disease, other drugs used at the same time or other non-drug related sources.

FDA Center for Veterinary Medicine publishes these words. Source: Adverse Event Reports for Animal Drugs and Devices, read on . The data have the reports that FDA received through .

This page is not veterinary advice. For an animal that is ill, speak to a veterinarian.

Contacting a veterinarianHow to report to FDA

From April 2013 to June 2026, FDA received 61,428 adverse event reports that name a drug with afoxolaner as its active ingredient. Of the 61,428 reports, 57,088 (92.9%) are about dogs.

In January to March 2026, FDA received 543 reports that name this drug. The signs that appear in the largest number of the 61,428 reports are "Vomiting", "Lethargy" and "Diarrhoea". A report is not proof that a drug caused a sign.

Reports that name this drug fell by 20.9% in the 12 months to June 2026, compared with the 12 months before. Reports for all animal drugs fell by 4.6% in the same periods. The newest months can get more reports in a later update. Reports about dogs are 92.9% of the reports that name this drug, and 72.6% of all reports.

Since the last update of the FDA data

The site recorded an update of the FDA data on . FDA changed these counts for January to March 2026:

  • All species: from 419 to 543.
  • Dog: from 394 to 500.
  • Other species or species not given: from 21 to 39.

January to March 2026 is the latest closed quarter in the data. In that quarter FDA received 543 reports that name afoxolaner: 500 dog, 4 cat, 0 horse, 39 other or not given.

All updatesFeed of updates (RSS)

Signs that the reports list

A sign is a coded term from the report. The words in brackets are a plain gloss of the term. The percentage is the share of the 61,428 reports that list the sign. One report can list more than one sign.

The sign that is in the largest number of the reports comes first.

  1. Vomiting23.7%14,589 reports
  2. Lethargy[unusually tired or inactive]10.8%6,626 reports
  3. Diarrhoea[diarrhea]8.8%5,412 reports
  4. Lack of efficacy (ectoparasite) - tick NOS[the product did not have the expected effect: ticks]8%4,943 reports
  5. Lack of efficacy (ectoparasite) - flea[the product did not have the expected effect: fleas]7%4,273 reports
  6. Seizure NOS[seizure, type not specified]6.6%4,063 reports
  7. Lack of efficacy (tick)[the product did not have the expected effect: ticks]5.5%3,389 reports
  8. Lack of efficacy (bacteria) - Borrelia[the product did not have the expected effect: Borrelia (Lyme disease bacteria)]5.2%3,221 reports
  9. Skin disorders NOS[NOS: not otherwise specified]4.3%2,621 reports
  10. Lack of efficacy (bacteria) - NOS[the product did not have the expected effect: target not specified]4.2%2,602 reports
  11. Pruritus[itching]3.9%2,413 reports
  12. Itching3.1%1,920 reports
  13. Anorexia[not eating]2.9%1,769 reports
  14. Tablets, Abnormal[a product quality report, not a sign in an animal]2.8%1,729 reports
Show the next 16 signs
  1. Lack of efficacy (flea)[the product did not have the expected effect: fleas]2.7%1,632 reports
  2. Not eating2.6%1,621 reports
  3. Panting2.3%1,436 reports
  4. Behavioural disorder NOS[behaviour change, type not specified]2.2%1,380 reports
  5. Shaking1.9%1,183 reports
  6. Scratching1.9%1,181 reports
  7. Other abnormal test result NOS[abnormal laboratory result, type not specified]1.9%1,138 reports
  8. Ataxia[unsteady, uncoordinated movement]1.8%1,090 reports
  9. Death1.7%1,053 reports
  10. Lack of efficacy (bacteria) - Anaplasma[the product did not have the expected effect: Anaplasma bacteria]1.5%936 reports
  11. Emesis[vomiting]1.3%799 reports
  12. Lack of efficacy (endoparasite) - heartworm[the product did not have the expected effect: heartworm]1.3%772 reports
  13. Death by euthanasia[the animal was euthanized]1.2%766 reports
  14. Erythema (for urticaria see Immune SOC)1.2%753 reports
  15. Tremor1.2%727 reports
  16. Inappetence[reduced appetite]1.2%725 reports

The list shows 30 of 2,001 coded signs. A report is not proof that a drug caused a sign. Download all signs (CSV)

Reports by species

  • Dog92.9%57,088
  • Human exposure0.1%86
  • Cat0.1%80
  • Otherunder 0.1%3
  • Other Canidsunder 0.1%3
  • Foxunder 0.1%1

The share is of all 61,428 reports that name afoxolaner. The other reports give a different species or no species.

Reports for each month, Jul 2021 to Jun 2026

Dog17,297 reports. Largest count in one month: 472 (Jun 2023)
Cat38 reports

No chart: no month has 5 or more reports.

Horse0 reports

No chart: no month has 5 or more reports.

Other or not given1,204 reports. Largest count in one month: 42 (Oct 2021)

The month is the month in which FDA received the report. Each chart has its own scale. FDA says that a report can take 3 to 6 months to reach the public data. The newest months can get more reports in a later update.

Reports by year

  • Dog
  • Cat
  • Horse
  • Other or not given
Reports that name afoxolaner, by the year in which FDA received them and by species
YearDogCatHorseOther or not givenAll species
20261,17050641,239
20252,9921201633,167
20243,829602664,101
20233,7881203004,100
20223,607202473,856
20214,100103454,446
20204,786704195,212
20195,115704325,554
20184,823403885,215
20177,2091005937,812
20167,224805107,742
20155,544313525,900
20142,881301753,059
20132000525

2026 has the reports that FDA received through Jun 2026. Download the years (CSV)

What the reports record

Outcome at the time of the report

  • Recovered/Normal28.6%17,569
  • Recovered with Sequela[recovered, with a lasting effect]0.2%138
  • Ongoing7.7%4,753
  • Died1.8%1,124
  • Euthanized1.2%749
  • Outcome Unknown53.5%32,891

An outcome in a report is not proof that the drug caused it. The person who sends the report gives the outcome. Each share is of the 61,428 reports that name afoxolaner.

A report about more than one animal can have more than one outcome.

Kind of report

  • Safety issue61.6%37,865
  • Lack of expected effectiveness28%17,195
  • Both safety and lack of expected effectiveness3.2%1,949
  • Manufacturing or product defect7.1%4,363
  • Other0.1%56

57,050 reports say if the event was serious. 34.8% of them have the serious flag. The person who sends the report sets the flag.

Show age, weight, breed and route

Age of the animal

  • Under 1 year13.3%8,170
  • 1 to 3 years24.6%15,090
  • 4 to 7 years21.1%12,986
  • 8 to 11 years14.5%8,930
  • 12 years and over6.4%3,926
  • Age not given20.1%12,326

Weight of the animal

  • Under 5 kg (11 lb)11.9%7,313
  • 5 to 9.9 kg (11 to 22 lb)19.4%11,927
  • 10 to 24.9 kg (22 to 55 lb)25.9%15,906
  • 25 to 44.9 kg (55 to 99 lb)24.1%14,774
  • 45 kg and over (99 lb and over)2.8%1,704
  • Weight not given16%9,804

Breed, where the report gives one breed

A breed with many animals has many reports.

Route in the report

  • Oral84.6%51,993
  • Other0.1%59
  • Topicalunder 0.1%29
  • Parenteralunder 0.1%6
  • Ophthalmicunder 0.1%4
  • Subcutaneousunder 0.1%3

Each bar is on a scale of 0 to 100%.

Approved animal drugs with this active ingredient (FDA Green Book)

This section is reference data. It has no report count.

The openFDA records give the value "MSK" for the brand name and for the manufacturer name of each drug. FDA says that MSK means "masked". So the site cannot count a report for a brand.

Brand names

  • NexGard

What the Green Book records give

Applications with an approval in force
1
Approved species
Dogs
Dose forms
Chewable Tablets
Routes
Oral
Sale
RX (prescription)
Earliest approval date in the records

The species, dose forms and routes are the words of the Green Book records for all the applications together. One product can have fewer. The label of a product gives its approved use.

Applications in the Green Book of 2 Nov 2026, pioneer applications (NADA) first
Brand nameActive ingredientsSponsorApproved speciesApplication
NexGardAfoxolanerBoehringer Ingelheim Animal Health USA, Inc.DogsNADA 141-406

Other pages with this ingredient

A report names a drug by its set of active ingredients. Each set has its own page. The list is in order of name.

Next in the A to Z list

All drugs by active ingredient. Brand names A to Z

FDA pages for this drug

The site checked these addresses on . The links open in a new tab.

Cite this page

Pet Drug Reports. Afoxolaner: adverse event reports that FDA received. https://petdrugreports.com/drug/afoxolaner/ Source: FDA Center for Veterinary Medicine, openFDA Animal and Veterinary adverse event reports, export of . Reports received through .

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Where the data come from

The counts come from the openFDA Animal and Veterinary adverse event files, export of 30 Oct 2026. The files have the reports that the FDA Center for Veterinary Medicine received through 26 Jun 2026. The files mask brand and manufacturer names. The site counts a drug by the active ingredients that each record gives, and gives no count to a brand, an application or a company. Ingredient names and the lists of approved products follow the FDA Green Book of 2 Nov 2026. The site does not use the application number that a record has.

The site does not publish report text, lot numbers or details of a reporter. FDA's record is the authority. See how the site counts reports, the data sources and the corrections page.

Questions about these reports

Which brand are these reports about?

The openFDA records give the value "MSK" for the brand name and for the manufacturer name of each drug. FDA says that MSK means "masked". So the site cannot count a report for a brand. The Green Book section of this page lists the brand names with this active ingredient.

Do the reports show that the drug caused the signs?

No. FDA states this about the data.

When looking at the results, be aware that there is no certainty that the reported drug or device caused the adverse event.

The adverse event may have been related to an underlying disease, other drugs used at the same time or other non-drug related sources.

FDA Center for Veterinary Medicine. Source: Adverse Event Reports for Animal Drugs and Devices

How many reports did FDA receive in the latest 12 months?

FDA received 2,823 reports in the 12 months to June 2026. It received 3,569 reports in the 12 months before. FDA says that a report can take 3 to 6 months to reach the public data. The newest months can get more reports in a later update.

What kinds of report are in the count?

Of the 61,428 reports received from April 2013 to June 2026, 61.6% are about a safety issue only. 31.2% are about a lack of expected effectiveness, alone or with a safety issue. 7.1% are about a defect of the product or its package.