Hair loss after Selamectin (Revolution) in cats

The FDA has received 8,059 reports of hair loss in cats after Selamectin. That is 37% of all reports for this medicine, compared with 14% across reports for all cat medicines, so it is reported unusually often with this medicine.

8,059Reports

3.0%Marked serious

5.5%Recovered

0.7%Died or euthanised

1 daysTypical onset

How soon it started

Same day

1,237 31%

1–2 days

1,603 40%

3–7 days

719 18%

1–4 weeks

317 7.8%

Over a month

163 4.0%

How the animals did

Recovered

437 5.4%

Recovered with lasting effects

3 0.0%

Still unwell when reported

1,853 23%

Died

42 0.5%

Euthanised

12 0.1%

Not known

5,712 71%

Problems reported at the same time

Application site reaction

3,351 42%

Itching

1,347 17%

Skin redness

1,082 13%

Skin rash or irritation

419 5.2%

329 4.1%

327 4.1%

231 2.9%

211 2.6%

Age of the animals

Under 1 year

680

1–3 years

2,431

4–7 years

2,259

8–11 years

1,268

12+ years

707

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 hair loss in cats?: 8,059 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).

Hair loss with similar medicines

Hair loss after Eprinomectin + Esafoxolaner + Praziquantel (NexGard Combo) 395 reports · 12% of its reports
Hair loss after Ivermectin (Heartgard) 20 reports · 2.1% of its reports
Hair loss after Eprinomectin + Praziquantel 54 reports · 9.2% of its reports

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