How to take care of a male cat after neutering?
I’d suggest that you do next to nothing out of the ordinary except use your common sense and watch your male cat, keep him inside so that you can watch him and also to ensure that he does not get into a jam outside which may stress him and create problems.
Note: the word “neutering” can refer to both spaying and neutering. On this page it means the castration of a male cat.

Male cat neutering. Photo: O’Dwyer and Jones vets.
I don’t recall my veterinarian giving me any particular instructions in respect of post-neutering care for my male tabby cat, Gabriel.
The operation is very straightforward and cats get over it very well. Both testicles are removed. The operation is not difficult or invasive (which may surprise some). The incision is small so stitches are not required. And the cat can often go home the same day. In fact, I would guess almost all cats go home the same day. There is no need for a follow up visit to the vet unless there are complications which I’d expect to be rare.
The book I have on cat medical matters omits any information on post-neutering care and therefore supports what I have written.
I actually somewhat surprised that people ask the question: “How to take care of a male cat after neutering?” using Google search. This is because the only time you want to ask that question is when you are taking your cat to the vet for neutering, in which case your vet will provide the answer, which will be that there is not much to do.
It makes sense to watch to ensure that there is no infection in the area of the operation. My cat was entirely back to normal as soon as he returned home after the operation.
There is big difference between neutering a male cat (usually castration) and spaying a female cat which is invasive and which entails removing the uterus, fallopian tubes and ovaries. There’ll be more care requirements after a spaying operation including possibly administering pain medication. As I recall there is no need for pain medication after male cat neutering. Also as spaying requires a general anesthetic a female cat will be groggy after the operation and Elisa mentions that the cat can have dry cat food but no water to avoid the possibility of choking. The same actually applies to neutering but I don’t remember following that advice.
If anyone has anything more enlightened to say on the subject please leave a comment.