Blood in vomit after Afoxolaner (NexGard) in dogs

143 reports to the FDA describe blood in vomit in dogs given Afoxolaner. That is 0.3% of all reports for this medicine, compared with 0.4% across reports for all dog medicines, so it is reported less often than average with this medicine.

143Reports
50%Marked serious
35%Recovered
12%Died or euthanised
2 daysTypical onset
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How soon it started

Same day
29 23%
1–2 days
42 34%
3–7 days
18 15%
1–4 weeks
16 13%
Over a month
19 15%

How the animals did

Recovered
49 34%
Recovered with lasting effects
1 0.7%
Still unwell when reported
24 17%
Died
12 8.4%
Euthanised
5 3.5%
Not known
52 36%

Problems reported at the same time

Age of the animals

Under 1 year
11
1–3 years
38
4–7 years
37
8–11 years
37
12+ years
13

About this medicine

Afoxolaner kills fleas and ticks; given as a monthly chewable.

Products with this ingredient include NexGard. The FDA hides brand names in its public data, so these reports cover every product with the same active ingredients.

In 2018 the FDA alerted owners and vets that isoxazoline products have been associated with neurologic reactions such as muscle tremors, wobbliness (ataxia) and seizures, including in animals with no history of them.

Questions owners ask

Can Afoxolaner cause blood in vomit in dogs?
143 reports link the two, but a report alone does not prove the medicine was the cause: other illnesses, other medicines or coincidence can be involved. Your vet can judge it for your animal.
How soon after a dose was it reported?
In half of the reports with dates, it started within 2 days of the first dose.
What should I do?
Don't give another dose until you've spoken to your vet, and keep the packaging so you can tell them the product and dose. Your vet can also report it to the FDA (or you can, through the manufacturer or FDA form 1932a).

Blood in vomit with similar medicines

All reported side effects of Afoxolaner in dogs · Medicines most reported with blood in vomit