What I've been using lately is Claritin, which may be the same stuff. I take it about an hour before I swim, and it seems to help. I also fixed the leak in my swim goggles, so that I'm not getting so much water in my eyes. Not sure if the problem comes from my eyes, my nose or my mouth, but I now seem to be keeping my eyes dry. I wear a nose clip and exhale slowly through the mouth and nose (even with the clip) to keep water getting up my nose. The hardest is to avoid getting water in my mouth. On a calm day, it's no problem, but when the water gets choppy and I swim into the wind, it's much tougher.
Up until recently, I was pushing my goggles (Aqua-Sphere Seal) against my face to create suction, but it seems that that was just sucking in the water. Lately I started just using the goggles with minimum suction and, to my surprise, they don't leak. This points to a problem with the seal around the lenses, I suspect, and I probably need to spring for a new pair. The one I'm using now is years old, but without the suction it still seems to hold. The question is for how much longer.