Be Aware of Serious Flu-Related Complications

Anyone can get sick with flu (including healthy people) and serious problems related to flu can happen at any age, but some people are at high risk of developing serious flu-related complications if they get sick. People experiencing difficulty breathing, shortness of breath, severe muscle pain or other emergency warning signs should obtain medical care right away.

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Flu Symptoms & Complications

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Flu Symptoms

Influenza (flu) can cause mild to severe illness, and at times can lead to death. Flu is different from a cold. Flu usually comes on suddenly. People who have flu often feel some or all of these symptoms:

fever* or feeling feverish/chills
cough
sore throat
runny or stuffy nose
muscle or body aches
headaches
fatigue (tiredness)
some people may have vomiting and diarrhea, though this is more common in children than adults.

*It’s important to note that not everyone with flu will have a fever.

Low Resolution Video

This video includes common signs and symptoms of flu.

Flu Complications

Most people who get flu will recover in a few days to less than two weeks, but some people will develop complications (such as pneumonia) as a result of flu, some of which can be life-threatening and result in death.

Sinus and ear infections are examples of moderate complications from flu, while pneumonia is a serious flu complication that can result from either influenza virus infection alone or from co-infection of flu virus and bacteria. Other possible serious complications triggered by flu can include inflammation of the heart (myocarditis), brain (encephalitis) or muscle (myositis, rhabdomyolysis) tissues, and multi-organ failure (for example, respiratory and kidney failure). Flu virus infection of the respiratory tract can trigger an extreme inflammatory response in the body and can lead to sepsis, the body’s life-threatening response to infection. Flu also can make chronic medical problems worse. For example, people with asthma may experience asthma attacks while they have flu, and people with chronic heart disease may experience a worsening of this condition triggered by flu.

People at High Risk from Flu

Anyone can get sick with flu (even healthy people), and serious problems related to flu can happen at any age, but some people are at high risk of developing serious flu-related complications if they get sick. This includes people 65 years and older, people of any age with certain chronic medical conditions (such as asthma, diabetes, or heart disease), pregnant women and children younger than 5 years, but especially those younger than 2 years old.

What are the emergency warning signs of flu?

People experiencing these warning signs should obtain medical care right away.

In 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

In 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

These lists are not all inclusive. Please consult your medical provider for any other symptom that is severe or concerning.

Cold vs Flu

cold vs flu
Signs and Symptoms	Cold	Influenza (Flu)
Symptom onset	Gradual	Abrupt
Fever	Rare	Usual; lasts 3-4 days
Aches	Slight	Usual; often severe
Chills	Uncommon	Fairly common
Fatigue, weakness	Sometimes	Usual
Sneezing	Common	Sometimes
Chest discomfort, cough	Mild to moderate; hacking cough	Common; can be severe
Stuffy nose	Common	Sometimes
Sore throat	Common	Sometimes
Headache	Rare	Common