Flu (Influenza)

Why Do I Need to Know About Flu Symptoms?

Seasonal flu is a contagious respiratory infection caused by different flu viruses. It's important to understand flu symptoms so you can seek immediate treatment, especially if you have a chronic medical condition.

The earlier you recognize that you have the flu can also make a difference in how long it lasts. Prescription medications called antiviral drugs -- Relenza and Tamiflu -- are most effective when given within 48 hours of the onset of flu symptoms. These flu drugs are effective against the typical strains of seasonal flu. They can decrease the duration of the flu by one day if used within this early window. These antivirals may also provide benefit if given even after two days, especially in people who are very sick.

How Will I Know if Flu Season Has Started?

Seasonal flu follows a fairly predictable pattern, starting in the fall and ending in the spring. A good sign that seasonal flu season has started is the sudden increase in the number of school-aged children sick at home with flu-like illness. This initial flu outbreak is soon followed by similar infection in other age groups, especially adults.
How Are Flu Symptoms Different From Cold Symptoms?

Unlike symptoms of a common cold, flu symptoms usually come on suddenly. It often starts with the abrupt onset of fever, headache, fatigue, and body aches. Here's a list of flu symptoms you might feel:

fever (usually high)
severe aches and pains in the joints and muscles and around the eyes
generalized weakness
ill appearance with warm, flushed skin and red, watery eyes
headache
dry cough
sore throat and watery discharge from your nose

Seasonal influenza is not usually associated with gastrointestinal symptoms, like diarrhea and vomiting, at least not in adults. However, these symptoms appear with stomach flu, which is a popular but inaccurate term for gastroenteritis.
What Are Common Flu Symptoms in Children?

Typical signs of seasonal flu in children include high-grade fever up to 104 degrees F (40 degrees C), chills, muscle aches, headaches, sore throat, dry cough, and just plain feeling sick. Flu symptoms in children may also cause vomiting and belly pain. These flu symptoms usually last for three to four days, but cough and tiredness may linger for up to two weeks after the fever has gone away. Other family members or close contacts often have a similar illness.

For in-depth information, see WebMD's Children and Flu.
What About Flu Symptoms in Infants and Toddlers?

In young children, seasonal flu symptoms may be similar to those of other respiratory tract infections such as croup, bronchitis, or pneumonia. Abdominal pain, vomiting, and diarrhea are frequently observed in young children. Vomiting tends to be more significant than diarrhea. Fever is usually high and irritability may be prominent.

Because young children are at increased risk of getting severe flu complications, the CDC recommends that all children aged 6 months get a seasonal flu vaccine every year.

For in-depth information, see WebMD's Children and Flu.
Are There Complications Associated With the Flu?

According to the CDC, complications of flu can include bacterial pneumonia, ear infections, sinus infections, dehydration, and worsening of chronic medical conditions such as congestive heart failure, asthma, or diabetes.

For in-depth information, see WebMD's Flu Complications.