Influenza (Flu)

Influenza (the flu) is a viral respiratory infection that spreads easily from person to person, typically peaking during colder months.

Flu Symptoms

Flu symptoms usually come on suddenly and include fever, chills, muscle aches, fatigue, headache, dry cough, and sore throat — the sudden onset and severity of body aches and fatigue are what most distinguish it from a common cold, which builds more gradually and causes milder symptoms.

How the Flu Spreads

The flu spreads mainly through droplets released when an infected person coughs, sneezes, or talks, and can also spread by touching a contaminated surface and then the face. People are typically contagious starting about a day before symptoms appear through roughly five to seven days after becoming sick.

Treatment

Most healthy people recover with rest, fluids, and over-the-counter medication for fever and aches. Antiviral medication can shorten illness duration and reduce complications when started within the first couple of days of symptoms, and is particularly considered for people at higher risk of complications.

Who Is at Higher Risk of Complications

Young children, adults over 65, pregnant women, and people with chronic conditions such as asthma, heart disease, or diabetes are more likely to develop complications like pneumonia, making the annual flu vaccine particularly important for these groups.

When to See a Doctor

Seek prompt medical care for difficulty breathing, chest pain, persistent dizziness, symptoms that improve then return with fever, or worsening of an existing chronic condition. In infants and young children, watch instead for bluish lips or face, fast or labored breathing, poor fluid intake, or unusual lethargy or irritability — these need prompt medical attention even without the adult warning signs above. Pregnant women should contact a doctor promptly at the first sign of flu symptoms, since flu can progress more seriously during pregnancy.