A lot of times when I have baggy, red eyes, it's from allergies. I had that reaction when I smoked weed, and I have it in response to nearly every other sort of weed and grass, too. Just my wacky immune system.

A mild antihistamine will help the allergic reaction itself, easing some of the itching. You can use an anti-redness/anti-allergy eye drop to ease the actual eye-related itching. I have good luck with drops called Opthcon-A. Make sure you're well hydrated and drinking plenty of clear fluids so you're producing plenty of tears themselves and your body's not having a puffy response because it's desperate to hold onto fluid. And for the puffy eye bags themselves, several tried-and-true anti-puff remedies are cucumber slices, which are cool and soothing. Also cut-open sections of aloe vera plant, if you have one of those, are soothing and gentle. One of those cooling plastic gel-filled eye masks you put in the fridge is good. And camomile tea bags soaked in cool water and squeezed out before they're applied as compresses work great, too.