Cat lethargic after receiving annual rabies and distemper shots at the same time- cause for concern?

The first time my cat received both of these shots during the same vet visit, she definitely was impacted by them.  For the rest of the day and up until about noon of the next day, she was very lethargic.  She just slept, didn't bother to eat, and was totally inactive.  This year she will be in need of both shots again (the distemper shot is given every three years and her rabies shot is annual).  I know cats can have some side effects after receiving vaccinations, just like people, but is this a serious reaction or normal?  If the reaction can cause more serious problems, I can have them given at different times.  She has never had any reaction when just receiving the rabies shot.

My cats both get quite lethargic after their annual shots. They don't lose their appetites though, and are back to normal the next day. For them, I think it's the stress of the visit that wears them out more than the shots.
Does your cat get super stressed at the vet? Maybe giving the shots separately would be a good idea, unless the stress of two visits outweighs the benefit?

She is not thrilled about the vet visit, but I wouldn't say she gets stressed.  She displays no after effect upon returning home, nor after only receiving the rabies shot.  Her reaction is only when she receives both shots at the same time.  No doubt, they stimulate her immune system sufficiently that she isn't feeling well afterwards.  I just want to make sure this type of response can be expected and not escalate into something more serious for future combo shots.

I have the vet give my cats benadryl,because the shots also make my cats lethargic.

Just about every week one or more of the cats or kittens at our local shelter gets shots, and lethargy for about a day afterwards is the norm. Lots of them have a reduced appetite. Just the stress of the vet visit is presumably a contributing factor.

Swelling of the face/throat and/or difficulty breathing within 10 - 30 minutes of the shots are an emergency. Our last cat had an allergic reaction to his one-year booster shots, but luckily his breathing was okay. He experienced vomiting and severe diarrhea.

Whenever it is an option, I would recommend not doing more than one vaccine at a time.  Many pets are fine with that schedule but some are not, and there's not any way to predict when an adverse event is going to occur.  If you know how to give vaccines, maybe you could ask your vet clinic if you could purchase the FVRCP vaccine from them and give it at home to avoid two office visit charges?  This also avoids the stress of an office visit.

There is no guarantee that this sort of thing won't escalate and frankly, I would worry that it would.  There were no signs of allergic reaction, though, it sounds like, which is a good sign.

Thanks for the replies.  Kat - having the shots given separately is what I will probably do.  I don't like seeing her so wiped out afterwards and don't want to take any chances with something more serious occurring.

It's normal for cats to be lethargic after vaccinations

I know people recommend giving vaccinations separately to avoid the lethargy afterwards but personally, I prefer that my Aby gets all at once He's normally super active and bouncing off the walls 24/7 so one day of him being sleepy is heaven for me