Didn't prevent heartworm after Selamectin (Revolution) in dogs

The FDA has received 8,789 reports of didn't prevent heartworm in dogs after Selamectin. That is 30% of all reports for this medicine, compared with 13% across reports for all dog medicines, so it is reported unusually often with this medicine.

8,789Reports

6.5%Marked serious

0.8%Recovered

1.2%Died or euthanised

292 daysTypical onset

How soon it started

Same day

11 3.5%

1–2 days

1 0.3%

3–7 days

2 0.6%

1–4 weeks

6 1.9%

Over a month

298 94%

How the animals did

Recovered

72 0.8%

Recovered with lasting effects

2 0.0%

Still unwell when reported

1,594 18%

Died

97 1.1%

Euthanised

11 0.1%

Not known

7,013 80%

Problems reported at the same time

Didn't work as expected

457 5.2%

156 1.8%

103 1.2%

87 1.0%

69 0.8%

65 0.7%

48 0.5%

42 0.5%

Age of the animals

Under 1 year

1–3 years

3,639

4–7 years

3,008

8–11 years

1,461

12+ years

334

About this medicine

Selamectin prevents heartworm and treats fleas, ear mites and some worms (spot-on).

Products with this ingredient include Revolution. The FDA hides brand names in its public data, so these reports cover every product with the same active ingredients.

Some herding breeds (for example Collies) carry the MDR1 gene variant and can be more sensitive to this drug class at high doses.

Questions owners ask

Can Selamectin cause didn't prevent heartworm in dogs?: 8,789 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 292 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 Ivermectin + Pyrantel (Heartgard Plus) 57,581 reports · 39% of its reports
Didn't prevent heartworm after Milbemycin Oxime + Spinosad (Trifexis) 10,801 reports · 8.3% of its reports
Didn't prevent heartworm after Moxidectin (ProHeart 6) 11,529 reports · 23% of its reports
Didn't prevent heartworm after Milbemycin Oxime + Praziquantel (Interceptor Plus) 8,433 reports · 27% of its reports
Didn't prevent heartworm after Milbemycin Oxime (Interceptor) 13,118 reports · 44% of its reports
Didn't prevent heartworm after Ivermectin (Heartgard) 3,385 reports · 28% of its reports
Didn't prevent heartworm after Ivermectin + Praziquantel + Pyrantel (Iverhart Max) 1,879 reports · 22% of its reports
Didn't prevent heartworm after Moxidectin + Pyrantel + Sarolaner (Simparica Trio) 319 reports · 28% of its reports

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