According to the Chicago Dental society, red wine, coffee, tea, blueberries, smoking or chewing tobacco and many more items cause the stains of teeth. To avoid the discoloring of teeth, just take some preventive measures habitually. Do brush regularly after eating and drinking with good quality toothpaste.
Medical radiation and chemotherapy also cause tooth yellowing. Some other medications for malaria and rheumatoid arthritis treatments also do the same. You can consult to the medical experts before taking any medication about its effect on teeth color.