Didn't prevent heartworm after Heartgard in dogs

The FDA has received 176 reports of didn't prevent heartworm in dogs after Heartgard. That is 47% of all reports for this medicine, compared with 13% across reports for all dog medicines, so it is reported unusually often with this medicine.

176Reports

100%Marked serious

0.6%Recovered

0.6%Died or euthanised

281 daysTypical onset

How soon it started

Same day

2 3.1%

1–2 days

0 0.0%

3–7 days

0 0.0%

1–4 weeks

0 0.0%

Over a month

63 97%

How the animals did

Recovered

1 0.6%

Still unwell when reported

166 94%

Euthanised

1 0.6%

Not known

8 4.5%

Problems reported at the same time

Medication error

5 2.8%

Overdose

4 2.3%

Drug dose administration interval too long

3 1.7%

Drug dose administration interval too short

2 1.1%

Drug dose omission

2 1.1%

Urinary tract infection

1 0.6%

Inappropriate schedule of drug administration

1 0.6%

Lethargy

1 0.6%

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 Heartgard cause didn't prevent heartworm in dogs?: 176 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 281 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 prevent heartworm with similar medicines

Didn't prevent heartworm after Melarsomine (Immiticide) 7,132 reports · 31% of its reports
Didn't prevent heartworm after Diphenhydramine 71 reports · 1.5% of its reports
Didn't prevent heartworm after Butorphanol 33 reports · 0.7% of its reports
Didn't prevent heartworm after Cefpodoxime 24 reports · 0.6% of its reports
Didn't prevent heartworm after Tramadol 79 reports · 2.1% of its reports
Didn't prevent heartworm after Cephalexin 43 reports · 1.6% of its reports
Didn't prevent heartworm after Chondroitin + Glucosamine 35 reports · 1.3% of its reports
Didn't prevent heartworm after Glucosamine 24 reports · 1.3% of its reports
Didn't prevent heartworm after Acepromazine 43 reports · 2.4% of its reports
Didn't prevent heartworm after Enalapril 24 reports · 1.5% of its reports

All reported side effects of Heartgard in dogs · Medicines most reported with didn't prevent heartworm