Didn't stop fleas after Selamectin (Revolution) in dogs

The FDA has received 3,379 reports of didn't stop fleas in dogs after Selamectin. That is 11% of all reports for this medicine, compared with 6.2% across reports for all dog medicines, so it is reported unusually often with this medicine.

3,379Reports

2.9%Marked serious

1.1%Recovered

0.2%Died or euthanised

37 daysTypical onset

How soon it started

Same day

124 19%

1–2 days

28 4.4%

3–7 days

46 7.2%

1–4 weeks

102 16%

Over a month

341 53%

How the animals did

Recovered

37 1.1%

Still unwell when reported

366 11%

Died

4 0.1%

Euthanised

2 0.1%

Not known

2,970 88%

Problems reported at the same time

Didn't stop ticks

234 6.9%

Itching

197 5.8%

Didn't work as expected

142 4.2%

Drug dose administration interval too short

82 2.4%

Skin rash or irritation

64 1.9%

Didn't stop worms

59 1.7%

Didn't stop mites

57 1.7%

Vomiting

50 1.5%

Age of the animals

Under 1 year

467

1–3 years

809

4–7 years

729

8–11 years

437

12+ years

203

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 stop fleas in dogs?: 3,379 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 37 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

Didn't stop fleas after Ivermectin + Pyrantel (Heartgard Plus) 483 reports · 0.3% of its reports
Didn't stop fleas after Milbemycin Oxime + Spinosad (Trifexis) 8,717 reports · 6.7% of its reports
Didn't stop fleas after Moxidectin (ProHeart 6) 70 reports · 0.1% of its reports
Didn't stop fleas after Milbemycin Oxime + Praziquantel (Interceptor Plus) 171 reports · 0.5% of its reports
Didn't stop fleas after Milbemycin Oxime (Interceptor) 118 reports · 0.4% of its reports
Didn't stop fleas after Ivermectin (Heartgard) 451 reports · 3.8% of its reports
Didn't stop fleas after Ivermectin + Praziquantel + Pyrantel (Iverhart Max) 38 reports · 0.4% of its reports
Didn't stop fleas after Moxidectin + Pyrantel + Sarolaner (Simparica Trio) 21 reports · 1.8% of its reports

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