Didn't stop fleas after Diphenhydramine in dogs

174 reports to the FDA describe didn't stop fleas in dogs given Diphenhydramine. That is 3.7% of all reports for this medicine, compared with 6.2% across reports for all dog medicines, so it is reported less often than average with this medicine.

174Reports
12%Marked serious
16%Recovered
0.0%Died or euthanised
52 daysTypical onset
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How soon it started

Same day
9 8.6%
1–2 days
4 3.8%
3–7 days
2 1.9%
1–4 weeks
25 24%
Over a month
65 62%

How the animals did

Recovered
17 9.8%
Recovered with lasting effects
10 5.7%
Still unwell when reported
16 9.2%
Not known
131 75%

Problems reported at the same time

Itching
47 27%
Didn't work as expected
43 25%
Vomiting
17 9.8%
Unpalatable
9 5.2%
Lethargy
9 5.2%
Hair loss
8 4.6%
Reddening of the skin
7 4.0%
Loss of appetite
6 3.4%

Age of the animals

Under 1 year
7
1–3 years
57
4–7 years
55
8–11 years
32
12+ years
16

About this medicine

Type: medicine.

Questions owners ask

Can Diphenhydramine cause didn't stop fleas in dogs?
174 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 52 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).

Didn't stop fleas with similar medicines

All reported side effects of Diphenhydramine in dogs · Medicines most reported with didn't stop fleas