Is my cat in danger after his first vaccination?
Babies get sick after being vaccinated as well. His body is reacting to the viruses and building up his immune system. Eventually he will get over it and go back to his chaotic, destructive self in no time.
This is a normal reaction after getting vaccinated. The same thing happens with babies and toddlers. In fact the same thing often happens with adults who have just received a flu shot.
heart o' gold
Vaccines are ... basically diluted poisons and full of heavy metals. It is normal for the animal to feel dragged out after vaccines. When I vaccinate my animals I always plan to be home resting with them for a couple days ... or longer while they recover. For some of the vaccines I actually stay at the vet in the parking lot for an hour or two so if my pet has a reaction I will be able to get medical help immediately. I would NEVER vaccinate my own pet, ever.
It sounds more like he got the rabies vaccine. This vaccine is not measured out like the other vaccines are, so an adult cat who has never been vaccinated before gets the same dose as a kitten. Its hard for his body to process. Give him time and he should start to feel better soon. Give him love of love and treats. Be sure he eats, drinks, and uses the box. Luckily, the rabies boosters aren't nearly as bad, so as long as you keep him up to date on his shots, he won't need to feel like this ever again.