Didn't work as expected after Selamectin (Revolution) in dogs

The FDA has received 2,253 reports of didn't work as expected in dogs after Selamectin. That is 7.7% of all reports for this medicine, compared with 13% across reports for all dog medicines, so it is reported less often than average with this medicine.

2,253Reports

6.9%Marked serious

2.2%Recovered

1.0%Died or euthanised

89 daysTypical onset

How soon it started

Same day

45 6.8%

1–2 days

16 2.4%

3–7 days

31 4.7%

1–4 weeks

109 17%

Over a month

456 69%

How the animals did

Recovered

48 2.1%

Recovered with lasting effects

1 0.0%

Still unwell when reported

1,015 45%

Died

11 0.5%

Euthanised

12 0.5%

Not known

1,166 52%

Problems reported at the same time

Didn't prevent heartworm

457 20%

291 13%

142 6.3%

75 3.3%

74 3.3%

Drug dose administration interval too short

59 2.6%

Vomiting

53 2.4%

Diarrhea

42 1.9%

Age of the animals

Under 1 year

402

1–3 years

605

4–7 years

490

8–11 years

349

12+ years

117

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 work as expected in dogs?: 2,253 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 89 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 work as expected with similar medicines

Didn't work as expected after Ivermectin + Pyrantel (Heartgard Plus) 27,781 reports · 19% of its reports
Didn't work as expected after Milbemycin Oxime + Spinosad (Trifexis) 13,050 reports · 10% of its reports
Didn't work as expected after Moxidectin (ProHeart 6) 2,005 reports · 4.0% of its reports
Didn't work as expected after Milbemycin Oxime + Praziquantel (Interceptor Plus) 3,979 reports · 13% of its reports
Didn't work as expected after Milbemycin Oxime (Interceptor) 3,131 reports · 11% of its reports
Didn't work as expected after Ivermectin (Heartgard) 741 reports · 6.2% of its reports
Didn't work as expected after Ivermectin + Praziquantel + Pyrantel (Iverhart Max) 1,337 reports · 16% of its reports
Didn't work as expected after Moxidectin + Pyrantel + Sarolaner (Simparica Trio) 123 reports · 11% of its reports

All reported side effects of Selamectin in dogs · Medicines most reported with didn't work as expected