Thanks for the question Hank 180.
The active ingredient in glow sticks, dibutyl phthalate, is not very toxic to cats. This substance has a bad taste and will make them drool or become agitated or vomit but thats about it and it should pass quickly.
You should thoroughly wash out your cat's mouth with water then give him some milk to drink. Be sure to wash any of the glow stick contents from your cat's fur.
Of course if your cat shows any other symptoms or the problem does not quickly resolve you should have your vet check the cat over. his would be unlikely though.
If I have not covered your question fully enough or you would like to ask more I will be online for the next hour or so and I will be at your disposal.Scott Nimmo BVMS MRCVS
Cat Veterinarian
I have 28 years experience in all aspects of feline medicine and surgery.