Fever after Sarolaner + Selamectin (Revolution Plus) in cats

The FDA has received 182 reports of fever in cats after Sarolaner + Selamectin. That is 2.2% of all reports for this medicine, compared with 3.2% across reports for all cat medicines.

182Reports
75%Marked serious
16%Recovered
4.9%Died or euthanised
1 daysTypical onset
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How soon it started

Same day
84 47%
1–2 days
43 24%
3–7 days
26 14%
1–4 weeks
20 11%
Over a month
7 3.9%

How the animals did

Recovered
30 16%
Still unwell when reported
128 70%
Died
4 2.2%
Euthanised
5 2.7%
Not known
15 8.2%

Problems reported at the same time

Age of the animals

Under 1 year
53
1–3 years
58
4–7 years
34
8–11 years
24
12+ years
6

About this medicine

Sarolaner kills fleas, ticks and some mites; monthly. Selamectin prevents heartworm and treats fleas, ear mites and some worms (spot-on).

Products with this combination include Revolution Plus. The FDA hides brand names in its public data, so these reports cover every product with the same active ingredients.

In 2018 the FDA alerted owners and vets that isoxazoline products have been associated with neurologic reactions such as muscle tremors, wobbliness (ataxia) and seizures, including in animals with no history of them.

Questions owners ask

Can Sarolaner + Selamectin cause fever in cats?
182 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 Sarolaner + Selamectin in cats · Medicines most reported with fever