Cat Allergies Treatment

my cat got outside and was out all night now her eyes are all runny and swolen… think she got into something she is allergic to?

And if so, how much? She is about 7 or 8 pounds.

Is there anything that is okay to give to cats if they have allergies? I am beginning to think that my cat has allergies. She sneezes all the time and her eyes water alot. She also has a terrible cough, but that could just be hair balls maybe. Anyone have any suggestions?? Thanks
Yeah I kinda figured the vet thing, but when you are a college student you can’t really afford a vet. They cost way too much, but thanks for the advice.

I head that if you give 1 vitamin tab a day it will alleviate cat allergies.
Trouble is..did he mean me or the cat? AND does i work???

p.s. We want a cat but we have slight, not major allergies.

Thank you.