My cat has a swelling next to its eye. What should I do?

This depends on the location of the swelling and what is causing it.

If the skin next to the eye is swollen, and the eye itself looks completely normal, then the swelling may be due to an insect bite, be a result from a cat fight or some other kind of trauma. Try to see if you can find a wound, and if you do, clean the area with water and a clean towel. If you have a buster collar, put it on your cat and keep your cat indoors. If the swelling does not go down the next day or if your cat seems tired or unwell in any way you should contact a veterinarian.

If the eye or eyelids are swollen so that it is difficult to see the eye, or if the eye seems to be protruding you should seek veterinary care as soon as possible on the same day you noticed the change.