Behaviour change after Selamectin (Revolution) in cats

822 reports to the FDA describe behaviour change in cats given Selamectin. That is 3.7% of all reports for this medicine, compared with 5.4% across reports for all cat medicines.

822Reports
14%Marked serious
19%Recovered
7.3%Died or euthanised
Same dayTypical onset
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How soon it started

Same day
333 64%
1–2 days
86 17%
3–7 days
34 6.6%
1–4 weeks
35 6.7%
Over a month
31 6.0%

How the animals did

Recovered
154 19%
Recovered with lasting effects
4 0.5%
Still unwell when reported
162 20%
Died
45 5.5%
Euthanised
15 1.8%
Not known
442 54%

Problems reported at the same time

Age of the animals

Under 1 year
123
1–3 years
242
4–7 years
188
8–11 years
117
12+ years
83

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 behaviour change in cats?
822 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 the same 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).

Behaviour change with similar medicines

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