What can I put on the inside of my windows to keep them from fogging ? The house is old and poorly insulated.?

scuba divers found that saliva would stop there dive masks from fogging thats why you see them spitting in the mask then rinsing it in the ocean but i believe now they have a spray thay use instead hardware store might know if not call a dive shop or go online and google dive equipment or if money is not a problem any of the answers above are correct

Get new gas filled window replacements they save on heat and you get tax break and they dont fog

they fog because of the heat put storm windows on the out side will help

You could try using rain-x. It is used for car's windshields to make rain drops slip off but it may work on windows in a house, too.

they make plastic that fits over the window on the inside sold at any home improvement store