The flu, also known as influenza, is a highly contagious virus with highly individual associated symptoms. Many of the symptoms preceding the flu are similar to the common cold. Unlike the common cold, the flu can, in the very young and very old, weaken the immune system to the point of death from complications. Knowing the early symptoms that precede a full blown flu invasion may assist you in preparing for the pending attack on your immune system.
Aches and Chills
The flu virus attacks your immune system and depletes your ability to regulate your body's energy and thermostat. Just prior to realizing you have the flu, you may be achy from head to toe. If you find yourself reaching for a blanket in a comfortable environment, you might want to check your temperature and see if you are running a low grade fever. According to the Centers for Disease Control and Prevention, you may or may not develop a fever with the flu. Headaches and general weakness, or lethargy, are also early symptoms preceding the flu.
Gastrointestinal Upset
Nausea, vomiting, and diarrhea may precede the flu by days to hours. Nausea, with or without vomiting, is a common symptom. Nausea can come in the form of loss of appetite; perhaps your lunch had an off taste. This gastrointestinal upset is caused by the overgrowth of bacteria in your system; as the flu virus initiates an attack on your immune system it becomes overwhelmed and cannot support normal functions like flushing out the toxins in your system. Increase your fluid intake in preparation for the oncoming onslaught--your body will thank you.
Cough and Runny Nose
Days before the flu sets in you may notice a drippy nose, cough or sneezing. These respiratory symptoms are similar to the common cold, but unlike the cold, they will not be accompanied with a sore throat. Nasal discharge is more prevalent in children, and should be watched for development of ear infections. These symptoms are products of a busy immune system; while your body is fighting the flu virus there is no defense left to fight off respiratory illnesses. Initially, these nasal and cough secretions will be clear, unless you have a pre-existing medical condition.
Pre-existing Conditions
Especially in children, pre-existing medical conditions will usually worsen a few days prior to getting the flu. Children prone to ear infections or pneumonia can develop these conditions as their immune system is preoccupied trying to fight off the flu, and bacteria can grow in the fragile ear canals and lungs. Adults with pre-existing diagnoses, especially lung conditions, will frequently notice an increase or exaggeration of cough and a change in secretions from clear to yellow prior to the flu onset.
