I have a Catfolk kitten rogue playing in my Slumbering Tsar game, and during the game the PC came about the idea of growing, and use of Catnip, and I have no clue how to handle it with the basic assumption that they will end up hallucinating much like our real life companions do. Knowing what we do, that each cat responds uniquely to the plant, I didn't really know how to deal with it so I came up with a simple table based off half a minute of googling.

Even results are ignored every use, as it doesn't work on some cats. Rolling on a d10, and on an odd result roll again until until an even result appears.

1 - Hallucinations

3 - Drowsiness

5 - Aggression

7 - Arousal (Horniness)

9 - Extreme Hyperactivity

It feels fudged, and I really don't like it so well, so I come to you all hoping you have some ideas?

My cat hates the stuff, runs under the bed and hides.

Greg

Hey hey hey hey

Sniff catnip everyday

This is a simple poison with the initial damage being Wisdom Damage and secondary being effected as if by confusion. Cure 1 save. I'd probably say DC 11-13.

You could use the GMG drug rules but I think they're overly punitive.

The catfolk is affected by catnip as though under the effect of the Polypurpose Panacea spell.

catfolk aint cats any more than humans is monkeys. so catnip prolly dont work on them.

but if you want to roll play it for spits and shiggles give them something like

+2 dex, +2 str, -2 int, -2 wis and roll random action rolls so that when ever they try to do something they have a 75% chance of doing what they want to do and a 25% chance of doing something else

something else does not have to be bad like attacking an ally... maybe they want to attack the target but instead they grapple it and start nibbling its ears.

or maybe instead of shooting a bow they try to hoola hoop with it.

or they run around the bar offering sex to the person with the longest name.

you could just use the confused condition.

Maybe a will save dc 10+ the catfolk's level/HD.

If fail, roll 1d6

Facination 1d4 rounds
Hideous Laughter 1d4 rounds
Berserk (Rage for 1d4 rounds)
Confusion 1d6 rounds (will not give chase, only attacks creatures within 20 feet in an attempt to protect the catnip)
Loyalty (Wielder of catnip can offer a "Suggestion" as per the spell, duration is 1d4 rounds. If catfolk targets itself, there is a 50% chance of the catfolk being loyal to a random creature or humanoid within 60 feet. If not, then roll again.)
Fear (catfolk can only take move actions for 1d4 rounds, and all skills take a -10 on rolls.)

This is more diabolical than our dead catfolk comments here...

I play a catfolk too btw, and anytime there is anything 'curious' (dancing lights, a small bird or rodent, tiny creature of any sort, or a small dust cloud, my character kiosk gets a will save DC 15 (I impose it on myself) If I win, its a mild facination. If I lose, I am compelled to chase and play with it until I am out of sight, or something interacts with me.

Combat would "snap" me out of it immediately though.

Maybe that would be more effective?

Did you look here for some ideas?

http://paizo.com/pathfinderRPG/prd/mastery/drugsAndAddiction.html#drugs

I'm sure you could model it after something there pretty easily.