Scar after Diphenhydramine in dogs

20 reports to the FDA describe scar in dogs given Diphenhydramine. That is 0.4% of all reports for this medicine, compared with 0.0% across reports for all dog medicines, so it is reported unusually often with this medicine.

20Reports

5.0%Marked serious

20%Recovered

0.0%Died or euthanised

3 daysTypical onset

How soon it started

Same day

4 21%

1–2 days

3 16%

3–7 days

4 21%

1–4 weeks

7 37%

Over a month

1 5.3%

How the animals did

Recovered

2 10%

Recovered with lasting effects

2 10%

Still unwell when reported

1 5.0%

Not known

15 75%

Problems reported at the same time

Didn't work as expected

18 90%

Injection site reaction

17 85%

12 60%

8 40%

5 25%

4 20%

3 15%

Enlarged lymph node (localised)

3 15%

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 scar in dogs?: 20 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 3 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).

Scar with similar medicines

Scar after Butorphanol 25 reports · 0.6% of its reports
Scar after Famotidine 20 reports · 0.8% of its reports
Scar after Tigilanol Tiglate 26 reports · 1.3% of its reports

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