Hi I have a 16 year old indoor cat. When it's summer time I give him fresh grass every once in a while. He always gets mad about it, you don't even have to show him that you've brought some grass, he'll smell it immediately and start meowing anxiously. The weird thing is that he throws up very often after he's eaten it, every second time I'd say. Is it normal? Why does it happen? I'm sure he needs vitamins and grass is a good source of them but it's meaningless if he vomits like that all the time. -.- Please advise!
its completley normal dont worry they eat it to help them throw up hair balls and anything else nasty down there
kittehlewis is right ... kitties need grass to aid in their digestion and to rid their tummies of nasty stuff, so throwing up is perfectly normal, and actually a good thing.

I would suggest planting a small dish of cat grass inside for your kitty so that he has his grass all year instead of just in the summer. It will help to keep his digestive system in top condition.
Thanks! I feel better now. But I'm kinda surprised it's common. I mean I always thought grass was supposed to be a sourse of vitamins. How can cats get vitamins from it then if throwing up is the expected outcome?
I did try to plant a small dish of cat grass but those seeds I can buy in pet stores, they grow into really odd grass absolutely different from what I can bring him in summer. He always show less interest in this "home made" green, it doesn't even smell like grass in most cases, ie much less than the outdoor variety. Its shape is different too: much thiner and much less springy. He doesn't puke that often after eating it if ever at all. I tried to buy the seeds in different pet stores but all the same story so I finally gave it up. If there are options I've missed please let me know, I'll be grateful.
You're most welcome.

Even if your kitty throws up, the essential nutrients and vitamins have already been ingested through the moisure in the grass.

Instead of cat grass, buy some regular grass seed to plant. Then he'll be getting the same stuff that grows outdoors.
Thanks again. I hope there is really enough time for the nutrients and vitamins to be digested because his vommiting usually happens within about 5 mins after he's eaten the grass.