To know if one is allergic to cats, watch for symptoms such as sneezing, runny or stuffy nose, itchy or watery eyes, coughing, wheezing, chest tightness, skin rash or hives, and itchy throat. These symptoms often appear soon after exposure to a cat or cat dander. For a definitive diagnosis, a visit to an allergist is recommended. They typically perform a skin-prick test, where a small amount of cat allergen is pricked into the skin to check for a reaction like redness or swelling. Blood tests may also be used to detect allergy antibodies. Avoiding cats for a period of time to see if symptoms improve can also help distinguish cat allergies from other causes. If symptoms occur specifically around cats and are consistent, it's likely a cat allergy, but formal testing confirms it and rules out other causes.