In general, blocked tear duct can causes a series problems. While some nose problems are also causes of blocked tear duct. It's really a bad and terrible thing to suffer blocked tear duct is not a good thing. Blocked tear duct is the pathway partial or complete blockage, which most commonly occurs on new born babies. But it does not mean that adults can avoid it. Sinus infection can spread through anastomosing veins or by direct extension to close structures. Allergies is one of causes of sinus infection. If you have sinus infection, your condition will be much worse when you get cold. I have two friends who are suffering sinus infection and they said their nose always have something and cannot get out of them. Fortunately, they don't infect blocked tear duct. So you should pay attention to your health. When you get sinus infection, stay at home and take some medicines under the instruction of a doctor. You also need to avoid cold in that cold may lead to blocked tear duct according to your conditions. If you already have blocked tear duct, thus doctor's suggestions are so vital. Good luck for you.