My cat seems to have the classic symptoms of a hair ball.  He vomits
about 10 minutes after eating anything solid.  Even a single piece of
food will make him vomit.  It makes him really miserable for about 10
or 15 minutes and then he's OK.

Otherwise he's fine.  He drinks, pees, poops, plays and does everything
else he should.  I've been making him cat food "soup" by putting a can
of cat food in the blender with some water.  He's not fond of it but if
I mix some tuna juice with it he laps it up.  This does not make him
vomit.  He isn't eating quite as much as before because he really
doesn't like it but is eating at least the equivalent of one small can
per day.  Tomorrow I hope to buy some other flavors to see if he likes
them better.

This has been going on for two days.  I've been giving him hair ball
medicine twice a day but so far it hasn't helped.

Is there anything else I should try?  Should I give the hair ball
medicine another day or two?  Since he will eat the soup and since it's
nourishing I'm not in a panic.   I'd rather not run to the vet if
there's something else I could be doing.

Another question:  does the hair ball medicine prevent him from getting
what he needs from the food he's eating?  I try to give it to him about
two hours after he eats in the morning and then about an hour after he
eats at night.

Suggestions?

Thanks