Symptoms of flu include:

• fever (usually high)
• headache
• extreme tiredness
• dry cough
• sore throat
• runny or stuffy nose
• muscle aches

Stomach symptoms, such as nausea, vomiting and diarrhea, can also occur but are more common in children. Even though the term "stomach flu" is often used to describe these symptoms, they are caused by other viruses, bacteria or even parasites and are rarely due to influenza.

It is very hard to diagnose the flu based on symptoms alone; you may need a doctor to tell you if you have the flu or complications of the flu. Your doctor can perform tests to determine if you have the flu as long as you seek care within the first two or three days of symptoms.

Complications and Health Risks

Complications of flu can include:

• bacterial pneumonia
• ear infections
• sinus infections
• dehydration
• worsening of chronic medical conditions, such as congestive heart failure, asthma and diabetes

For most people, the flu is a minor illness that lasts for a few days and requires no major treatment. However, some get much sicker and may even have to be hospitalized. Those most at risk for flu complications include people over the age of 65, young children, women who are pregnant and anyone with serious, chronic health problems, such as asthma, heart disease, kidney disease, immune system problems, diabetes and blood disorders.

Symptoms At A Glance Chart Printer-friendly version

Disclaimer: This is not a substitute for a professional, on-site medical diagnosis. Visit your doctor or other healthcare professional for an accurate diagnosis of the flu or cold.