The flu is a contagious respiratory-tract infection caused by a virus called influenza. Though most people fully recover from this infection, over 35,000 people die each year in the United States due to flu complications, according to Medline Plus, a medical information website established by the National Institutes of Health. Early flu symptoms can be difficult to distinguish from common cold symptoms, but affected patients should discuss these symptoms with a physician if they occur.
Fever
The primary symptom that distinguishes the flu from a common cold is the emergence of a sudden fever. Early fever symptoms typically arise within two to three days after exposure to the influenza virus and can range in between 102 and 106 degrees Fahrenheit, according to MedlinePlus. Patients with early fever symptoms due to the flu can also experience chills or sweating that can last for up to five days. Infants, children or elderly patients who develop a high fever should be seen by a medical professional immediately.
Exhaustion or Fatigue
Severe exhaustion can arise as an early flu symptom in patients, according to medical experts at the University of Maryland Medical Center. Fatigue can make it difficult for affected patients to participate in usual daily activities, such as work or school. This early flu symptom can last up to two to three weeks after the onset of flu symptoms.
Headache
Headache pain is a common early symptom of the flu, according to the Mayo Clinic. Sensations of headache pain can be uncomfortable and may occur in conjunction with fever. Patients with recurrent or persistent headache symptoms can have difficulty concentrating during the day. Affected patients can control headache flu symptoms through the use of an over-the-counter pain medication, such as acetaminophen.
Body Aches
Patients with the flu can develop early symptoms of body aches and pains, according to the Centers for Disease Control and Prevention. Body aches and pain can contribute to muscle weakness, fatigue or exhaustion in affected patients. Sensations of pain and discomfort most frequently arise within the legs, back or arms, according to the Mayo Clinic. These symptoms may arise suddenly and can persist for several days before resolving.
