Lameness after Selamectin (Revolution) in cats

The FDA has received 102 reports of lameness in cats after Selamectin. That is 0.5% of all reports for this medicine, compared with 0.6% across reports for all cat medicines.

102Reports

16%Marked serious

18%Recovered

2.9%Died or euthanised

1 daysTypical onset

How soon it started

Same day

15 33%

1–2 days

13 28%

3–7 days

12 26%

1–4 weeks

4 8.7%

Over a month

2 4.3%

How the animals did

Recovered

18 18%

Still unwell when reported

23 23%

Died

3 2.9%

Not known

58 57%

Problems reported at the same time

45 44%

44 43%

34 33%

15 15%

8 7.8%

8 7.8%

7 6.9%

6 5.9%

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 lameness in cats?: 102 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 1 day 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).

All reported side effects of Selamectin in cats · Medicines most reported with lameness