Image of nurses' hands at computer keyboard

With flu season fast approaching, the Centers for Disease Control and Prevention has been encouraging people to receive flu shots. But in some instances the vaccine actually could result in dangerous complications, the CDC warns.

Those with certain allergies or pre-existing medical conditions could be at a heightened risk of complications, according to the CDC. The health agency strongly suggests anyone with the following allergies or conditions consult a doctor before getting the flu vaccine: allergies to eggs, previous adverse reaction to a flu shot, those currently ill with fever, and those who have ever developed a disease called Guillain-Barré Syndrome within six weeks of a flu shot.

Up to 90% of the 36,000 influenza-related deaths that happen in the U.S. every year occur within the senior population, according to CDC figures. Seniors living in care communities can be especially vulnerable to communicative diseases, and the CDC has recommended that all Americans over the age of 65 receive a flu vaccine.