Well, the weekend went fine. This was my daughter's boyfriend who was visiting. They are college students and getting a hotel is not in the budget, plus I'm not willing to tell them they can't stay with us. So I will try to mitigate it as much as possible. I will look into the air purifier, upgrade to the allergy filtering air filters, vacuum and dust like crazy and maybe even hire a house cleaner before their next visit to help me. Plus will keep the cat out of the room where he sleeps. Our downstairs is entirely hard floor surfaces which I think is better, but our upstairs is carpet that can trap the allergens.
Anyway, thank you all for the suggestions, I will incorporate these ideas and hope it helps.
He did ok btw, had some watery eyes when he first arrived, but he took antihistamines along with some eye drops that made it less bad. Still, I feel bad about it.