Injection site reaction after Diphenhydramine in dogs

398 reports to the FDA describe injection site reaction in dogs given Diphenhydramine. That is 8.4% of all reports for this medicine, compared with 1.0% across reports for all dog medicines, so it is reported unusually often with this medicine.

398Reports

42%Marked serious

19%Recovered

8.8%Died or euthanised

2 daysTypical onset

How soon it started

Same day

105 30%

1–2 days

73 21%

3–7 days

53 15%

1–4 weeks

74 21%

Over a month

42 12%

How the animals did

Recovered

71 18%

Recovered with lasting effects

3 0.8%

Still unwell when reported

124 31%

Died

14 3.5%

Euthanised

21 5.3%

Not known

165 41%

Problems reported at the same time

Swelling

223 56%

Didn't work as expected

138 35%

103 26%

97 24%

81 20%

71 18%

63 16%

59 15%

Age of the animals

Under 1 year

1–3 years

4–7 years

137

8–11 years

133

12+ years

About this medicine

Type: medicine.

Questions owners ask

Can Diphenhydramine cause injection site reaction in dogs?: 398 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).

Injection site reaction with similar medicines

Injection site reaction after Melarsomine (Immiticide) 3,290 reports · 15% of its reports
Injection site reaction after Polysulfated Glycosaminoglycan 263 reports · 4.8% of its reports
Injection site reaction after Butorphanol 479 reports · 11% of its reports
Injection site reaction after Cefpodoxime 81 reports · 2.0% of its reports
Injection site reaction after Tramadol 123 reports · 3.3% of its reports
Injection site reaction after Desoxycorticosterone Pivalate 165 reports · 4.9% of its reports
Injection site reaction after Propofol 170 reports · 5.5% of its reports
Injection site reaction after Isoflurane 126 reports · 4.6% of its reports
Injection site reaction after Cephalexin 31 reports · 1.2% of its reports
Injection site reaction after Atipamezole 225 reports · 8.5% of its reports

All reported side effects of Diphenhydramine in dogs · Medicines most reported with injection site reaction