Influenza, commonly known as “the flu,” is caused by a virus, which infects the respiratory tract. The flu is spread from person to person by direct contact or through virus-infected droplets coughed or sneezed in the air. Most people who get the flu recover completely in one to two weeks, but some develop serious and potentially life-threatening illnesses, such as pneumonia, especially elderly people.

The flu can often be treated at home but can require emergency care. The virus sometimes develops into bacterial pneumonia, ear infection, sinus infection, dehydration and worsening of chronic medical conditions. Very young children and the elderly are more susceptible to complications of the flu than the general population.

Keep in mind the flu usually lasts no more than a week or two and is best cured by getting rest, good nutrition and plenty of fluids. Although, it's best if you prevent getting the flu by receiving a flu vaccine. 

Warning signs of a flu emergency can differ for children and adults, and may include the following.

Signs for Children

• Fast breathing or trouble breathing
• Bluish lips or face
• Ribs pulling in with each breath
• Chest pain
• Severe muscle pain (child refuses to walk)
• Dehydration (no urine for 8 hours, dry mouth, no tears when crying)
• Not alert or interacting when awake
• Seizures
• Fever above 104°F
• In children less than 12 weeks, any fever
• Fever or cough that improve but then return or worsen
• Worsening of chronic medical conditions

Signs for Adults

• Difficulty breathing or shortness of breath
• Persistent pain or pressure in the chest or abdomen
• Persistent dizziness, confusion, inability to arouse
• Seizures
• Not urinating
• Severe muscle pain
• Severe weakness or unsteadiness
• Fever or cough that improve but then return or worsen
• Worsening of chronic medical conditions

This is not an exhaustive list. Contact your doctor regarding any other symptom that is severe or concerning.