Influenza - Adult

Influenza, also called "the flu," is a viral infection that mainly affects the respiratory tract. This includes the lungs, nose, and throat. The flu spreads easily from person to person (is contagious). It causes common cold symptoms, along with high fever and body aches.

What are the causes?

This condition is caused by the influenza virus. You can get the virus by:

Breathing in droplets that are in the air from an infected person's cough or sneeze.
Touching something that has the virus on it (has been contaminated) and then touching your mouth, nose, or eyes.

What increases the risk?

The following factors may make you more likely to get the flu:

Not washing or sanitizing your hands often.
Having close contact with many people during cold and flu season.
Touching your mouth, eyes, or nose without first washing or sanitizing your hands.
Not getting an annual flu shot.

You may have a higher risk for the flu, including serious problems, such as a lung infection (pneumonia), if you:

Are older than 65.
Are pregnant.
Have a weakened disease-fighting system (immune system). This includes people who have HIV or AIDS, are on chemotherapy, or are taking medicines that reduce (suppress) the immune system.
Have a long-term (chronic) illness, such as heart disease, kidney disease, diabetes, or lung disease.
Have a liver disorder.
Are severely overweight (morbidly obese).
Have anemia.
Have asthma.

What are the signs or symptoms?

Symptoms of this condition usually begin suddenly and last 4–14 days. These may include:

Fever and chills.
Headaches, body aches, or muscle aches.
Sore throat.
Cough.
Runny or stuffy (congested) nose.
Chest discomfort.
Poor appetite.
Weakness or fatigue.
Dizziness.
Nausea or vomiting.

How is this diagnosed?

This condition may be diagnosed based on:

Your symptoms and medical history.
A physical exam.
Swabbing your nose or throat and testing the fluid for the influenza virus.

How is this treated?

If the flu is diagnosed early, you can be treated with antiviral medicine that is given by mouth (orally) or through an IV. This can help reduce how severe the illness is and how long it lasts.

Taking care of yourself at home can help relieve symptoms. Your health care provider may recommend:

Taking over-the-counter medicines.
Drinking plenty of fluids.

In many cases, the flu goes away on its own. If you have severe symptoms or complications, you may be treated in a hospital.

Follow these instructions at home:

Activity

Rest as needed and get plenty of sleep.
Stay home from work or school as told by your health care provider. Unless you are visiting your health care provider, avoid leaving home until your fever has been gone for 24 hours without taking medicine.

Eating and drinking

Take an oral rehydration solution (ORS). This is a drink that is sold at pharmacies and retail stores.
Drink enough fluid to keep your urine pale yellow.
Drink clear fluids in small amounts as you are able. Clear fluids include water, ice chips, fruit juice mixed with water, and low-calorie sports drinks.
Eat bland, easy-to-digest foods in small amounts as you are able. These foods include bananas, applesauce, rice, lean meats, toast, and crackers.
Avoid drinking fluids that contain a lot of sugar or caffeine, such as energy drinks, regular sports drinks, and soda.
Avoid alcohol.
Avoid spicy or fatty foods.

General instructions

Take over-the-counter and prescription medicines only as told by your health care provider.
Use a cool mist humidifier to add humidity to the air in your home. This can make it easier to breathe.
- When using a cool mist humidifier, clean it daily. Empty the water and replace it with clean water.
Cover your mouth and nose when you cough or sneeze.
Wash your hands with soap and water often and for at least 20 seconds, especially after you cough or sneeze. If soap and water are not available, use alcohol-based hand sanitizer.
Keep all follow-up visits. This is important.

How is this prevented?

Get an annual flu shot. This is usually available in late summer, fall, or winter. Ask your health care provider when you should get your flu shot.
Avoid contact with people who are sick during cold and flu season. This is generally fall and winter.

Contact a health care provider if:

You develop new symptoms.
You have:
- Chest pain.
- Diarrhea.
- A fever.
Your cough gets worse.
You produce more mucus.
You feel nauseous or you vomit.

Get help right away if you:

Develop shortness of breath or have difficulty breathing.
Have skin or nails that turn a bluish color.
Have severe pain or stiffness in your neck.
Develop a sudden headache or sudden pain in your face or ear.
Cannot eat or drink without vomiting.

These symptoms may represent a serious problem that is an emergency. Do not wait to see if the symptoms will go away. Get medical help right away. Call your local emergency services (911 in the U.S.). Do not drive yourself to the hospital.

Summary

Influenza, also called "the flu," is a viral infection that primarily affects your respiratory tract.
Symptoms of the flu usually begin suddenly and last 4–14 days.
Getting an annual flu shot is the best way to prevent getting the flu.
Stay home from work or school as told by your health care provider. Unless you are visiting your health care provider, avoid leaving home until your fever has been gone for 24 hours without taking medicine.
Keep all follow-up visits. This is important.