Prolonged capillary refill time after Diphenhydramine in dogs

The FDA has received 31 reports of prolonged capillary refill time in dogs after Diphenhydramine. That is 0.7% 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.

31Reports

94%Marked serious

32%Recovered

32%Died or euthanised

Same dayTypical onset

How soon it started

Same day

21 72%

1–2 days

3 10%

3–7 days

1 3.4%

1–4 weeks

1 3.4%

Over a month

3 10%

How the animals did

Recovered

10 32%

Still unwell when reported

10 32%

Died

4 13%

Euthanised

6 19%

Not known

1 3.2%

Problems reported at the same time

21 68%

21 68%

19 61%

13 42%

11 35%

10 32%

10 32%

10 32%

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 prolonged capillary refill time in dogs?: 31 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).

Prolonged capillary refill time with similar medicines

Prolonged capillary refill time after Melarsomine (Immiticide) 57 reports · 0.3% of its reports

All reported side effects of Diphenhydramine in dogs · Medicines most reported with prolonged capillary refill time