Fever after Selamectin (Revolution) in cats

The FDA has received 787 reports of fever in cats after Selamectin. That is 3.6% of all reports for this medicine, compared with 3.2% across reports for all cat medicines.

787Reports
14%Marked serious
10%Recovered
10%Died or euthanised
1 daysTypical onset
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How soon it started

Same day
107 37%
1–2 days
94 32%
3–7 days
40 14%
1–4 weeks
36 12%
Over a month
13 4.5%

How the animals did

Recovered
81 10%
Still unwell when reported
171 22%
Died
70 8.9%
Euthanised
12 1.5%
Not known
453 58%

Problems reported at the same time

Age of the animals

Under 1 year
272
1–3 years
235
4–7 years
136
8–11 years
80
12+ years
34

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 fever in cats?
787 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).

Fever with similar medicines

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