Liver problems after Diphenhydramine in dogs

500 reports to the FDA describe liver problems in dogs given Diphenhydramine. That is 11% of all reports for this medicine, compared with 4.6% across reports for all dog medicines, so it is reported unusually often with this medicine.

500Reports
77%Marked serious
13%Recovered
26%Died or euthanised
1 daysTypical onset
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How soon it started

Same day
174 42%
1–2 days
63 15%
3–7 days
41 9.8%
1–4 weeks
46 11%
Over a month
95 23%

How the animals did

Recovered
60 12%
Recovered with lasting effects
6 1.2%
Still unwell when reported
238 48%
Died
44 8.8%
Euthanised
86 17%
Not known
66 13%

Problems reported at the same time

Age of the animals

Under 1 year
37
1–3 years
114
4–7 years
125
8–11 years
159
12+ years
63

About this medicine

Type: medicine.

Questions owners ask

Can Diphenhydramine cause liver problems in dogs?
500 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 1 day 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).

Liver problems with similar medicines

All reported side effects of Diphenhydramine in dogs · Medicines most reported with liver problems