Didn't stop mites after Selamectin (Revolution) in cats

The FDA has received 964 reports of didn't stop mites in cats after Selamectin. That is 4.4% of all reports for this medicine, compared with 1.0% across reports for all cat medicines, so it is reported unusually often with this medicine.

964Reports

2.0%Marked serious

0.5%Recovered

0.6%Died or euthanised

24 daysTypical onset

How soon it started

Same day

40 19%

1–2 days

7 3.3%

3–7 days

21 9.9%

1–4 weeks

47 22%

Over a month

98 46%

How the animals did

Recovered

5 0.5%

Still unwell when reported

117 12%

Died

5 0.5%

Euthanised

1 0.1%

Not known

836 87%

Problems reported at the same time

Didn't stop fleas

94 9.8%

Didn't work as expected

52 5.4%

Itching

38 3.9%

Drug dose administration interval too short

26 2.7%

Hair loss

21 2.2%

Didn't stop worms

15 1.6%

Application site reaction

10 1.0%

Didn't stop ticks

8 0.8%

Age of the animals

Under 1 year

254

1–3 years

155

4–7 years

111

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 didn't stop mites in cats?: 964 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 24 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 mites with similar medicines

Didn't stop mites after Eprinomectin + Esafoxolaner + Praziquantel (NexGard Combo) 53 reports · 1.6% of its reports
Didn't stop mites after Ivermectin (Heartgard) 29 reports · 3.0% of its reports
Didn't stop mites after Milbemycin Oxime (Interceptor) 126 reports · 31% of its reports

All reported side effects of Selamectin in cats · Medicines most reported with didn't stop mites