Frequent Illnesses: Understanding Possible Causes & Solutions

Question
Hi...
I have a general question that I need an opinion on. My sister who is 32 years old is always sick (standard head cold or cough or sore throat). What could be causing this? Basically, she has had a cold coming and going in strength for the last month. Sometimes she is sick all winter. She does not have any preexisiting conditions..we thought it was her old house (had issues with mold in the basement) but she recently moved last week. Could it be some type of issue like stress that is hurting her immune system? Any suppliments or vitamins she should be taking other than her standard vitamin c and daily vitamin?

Thanks!
Neal

Answer
sometimes people have allergies, or chronic sinus infections that never completely go away, sometimes it is from poor hygiene habits (usually rubbing their nose accidentally after shaking someone's hand) or if they are in a high risk profession (day care, teacher, job where you meet a lot of people)  Taking Vit C is good, but the big thing would be to make sure allergies are treated properly and being careful about handwashing and touching the face.....