Drug dose administration interval too short after Selamectin (Revolution) in cats

The FDA has received 203 reports of drug dose administration interval too short in cats after Selamectin. That is 0.9% of all reports for this medicine, compared with 0.4% across reports for all cat medicines, so it is reported unusually often with this medicine.

203Reports
7.4%Marked serious
0.5%Recovered
1.5%Died or euthanised
26 daysTypical onset
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How soon it started

Same day
17 19%
1–2 days
5 5.6%
3–7 days
4 4.4%
1–4 weeks
26 29%
Over a month
38 42%

How the animals did

Recovered
1 0.5%
Still unwell when reported
61 30%
Died
2 1.0%
Euthanised
1 0.5%
Not known
138 68%

Problems reported at the same time

Age of the animals

Under 1 year
47
1–3 years
39
4–7 years
29
8–11 years
23
12+ years
19

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 drug dose administration interval too short in cats?
203 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 26 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).

Drug dose administration interval too short with similar medicines

All reported side effects of Selamectin in cats · Medicines most reported with drug dose administration interval too short