Underdose after Selamectin (Revolution) in dogs

The FDA has received 179 reports of underdose in dogs after Selamectin. That is 0.6% of all reports for this medicine, compared with 1.0% across reports for all dog medicines, so it is reported less often than average with this medicine.

179Reports

17%Marked serious

8.9%Recovered

2.2%Died or euthanised

33 daysTypical onset

How soon it started

Same day

18 24%

1–2 days

4 5.4%

3–7 days

3 4.1%

1–4 weeks

10 14%

Over a month

39 53%

How the animals did

Recovered

16 8.9%

Still unwell when reported

100 56%

Died

1 0.6%

Euthanised

3 1.7%

Not known

59 33%

Problems reported at the same time

Didn't prevent heartworm

65 36%

Didn't work as expected

30 17%

24 13%

24 13%

12 6.7%

12 6.7%

12 6.7%

11 6.1%

Age of the animals

Under 1 year

1–3 years

4–7 years

8–11 years

12+ years

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 underdose in dogs?: 179 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 33 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).

Underdose with similar medicines

Underdose after Ivermectin + Pyrantel (Heartgard Plus) 1,810 reports · 1.2% of its reports
Underdose after Milbemycin Oxime + Spinosad (Trifexis) 750 reports · 0.6% of its reports
Underdose after Moxidectin (ProHeart 6) 180 reports · 0.4% of its reports
Underdose after Milbemycin Oxime + Praziquantel (Interceptor Plus) 153 reports · 0.5% of its reports
Underdose after Milbemycin Oxime (Interceptor) 118 reports · 0.4% of its reports
Underdose after Ivermectin (Heartgard) 99 reports · 0.8% of its reports
Underdose after Ivermectin + Praziquantel + Pyrantel (Iverhart Max) 98 reports · 1.1% of its reports

All reported side effects of Selamectin in dogs · Medicines most reported with underdose