Y i always get infected by common cold?

Colds or allergies: Frequent colds can be nasal allergies. Everyone gets colds on the fall and winter, but if you are always suffering from nasal symptoms, they may be something else.

Complicated: There are thousands of cold viruses and we can only get immune to one at a time. Most people get colds about 4 times a year, so you may not be as unusual as you think. Often our own immune system determines how sick we get from a given cold- some immune systems are a bit more "enthusiastic" than others and you will tend to get sicker from the same virus that only slightly bothered your friends.