Reduced responses after Diphenhydramine in dogs

26 reports to the FDA describe reduced responses in dogs given Diphenhydramine. That is 0.6% of all reports for this medicine, compared with 0.1% across reports for all dog medicines, so it is reported unusually often with this medicine.

26Reports

69%Marked serious

38%Recovered

38%Died or euthanised

Same dayTypical onset

How soon it started

Same day

14 61%

1–2 days

2 8.7%

3–7 days

2 8.7%

1–4 weeks

1 4.3%

Over a month

4 17%

How the animals did

Recovered

9 35%

Recovered with lasting effects

1 3.8%

Still unwell when reported

5 19%

Died

5 19%

Euthanised

5 19%

Not known

1 3.8%

Problems reported at the same time

16 62%

12 46%

11 42%

11 42%

10 38%

9 35%

8 31%

8 31%

Age of the animals

Under 1 year

1–3 years

4–7 years

8–11 years

12+ years

About this medicine

Type: medicine.

Questions owners ask

Can Diphenhydramine cause reduced responses in dogs?: 26 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 the same 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).

Reduced responses with similar medicines

Reduced responses after Melarsomine (Immiticide) 24 reports · 0.1% of its reports
Reduced responses after Tramadol 20 reports · 0.5% of its reports

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