Leucopenia after Diphenhydramine in dogs

The FDA has received 68 reports of leucopenia in dogs after Diphenhydramine. That is 1.4% of all reports for this medicine, compared with 0.3% across reports for all dog medicines, so it is reported unusually often with this medicine.

68Reports
59%Marked serious
12%Recovered
28%Died or euthanised
2 daysTypical onset
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How soon it started

Same day
22 37%
1–2 days
9 15%
3–7 days
2 3.4%
1–4 weeks
12 20%
Over a month
14 24%

How the animals did

Recovered
8 12%
Still unwell when reported
36 53%
Died
9 13%
Euthanised
10 15%
Not known
5 7.4%

Problems reported at the same time

Age of the animals

Under 1 year
8
1–3 years
14
4–7 years
23
8–11 years
17
12+ years
6

About this medicine

Type: medicine.

Questions owners ask

Can Diphenhydramine cause leucopenia in dogs?
68 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).

Leucopenia with similar medicines

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