Wash the scratch with soap and running water for several minutes, then watch for ordinary infection: spreading redness, pus, warmth, worsening pain, fever.
The named risk is cat scratch disease: the CDC says scratches from cats, especially kittens, can deposit flea-borne Bartonella bacteria, causing a bump at the site and swollen, tender lymph nodes one to three weeks later, and most cases resolve without antibiotics. Get seen for swelling lymph nodes weeks later, fever, deep or hand or joint-area scratches, or if you are immunocompromised. Flea control on the cat is the real prevention.
What to do
Common questions
My cat scratched me - should I worry?
Most cat scratches are annoying, not dangerous, and the right response is wash and watch. Wash the scratch with soap and running water for several minutes, then watch it over the coming days for the ordinary infection signs: spreading redness, swelling, warmth, pus, worsening pain, or fever. That pattern needs a doctor and often antibiotics, and cat scratches and bites are infection-prone enough that hand wounds and deep punctures deserve a lower threshold for getting seen, per NHS bite guidance. The named complication is cat scratch disease: the CDC explains people usually get it from scratches by domestic or feral cats, especially kittens, when the scratch is contaminated with flea dirt carrying Bartonella bacteria, and the signature is a small bump at the scratch site plus enlarged, tender lymph nodes one to three weeks later, sometimes with a low-grade fever. The good news: most cases resolve without antibiotic treatment, though antibiotics speed recovery and are recommended for immunocompromised patients. See a doctor for lymph nodes swelling weeks after a scratch, fever alongside, any eye or neurological symptoms, or if you are immunocompromised, pregnant, or the scratch is deep, on the hand, or near a joint. Flea control on the cat is the real prevention.