Flu: What You Need to Know
The flu is an easily spread respiratory tract infection caused by a virus.
Most people are sick with the flu for only a few days, but young children, the elderly and those with impaired immune systems may develop a much more serious illness.
Flu viruses continually change. Vaccines given each year fight the strain predicted to cause illness that year.
Flu season can begin as early as October and most commonly peaks in the U.S. in January or February.
The flu shot is one of the best — and easiest — ways to keep you and your family healthy.
What causes the flu?
The flu is caused by a virus. Viruses are generally passed from person to person through the air when an infected person sneezes or coughs.
But the virus can also live for a short time on objects like doorknobs, pens, pencils, keyboards, phones, and cups or eating utensils. So you can also get the flu by touching something that has been recently handled by someone infected with the virus and then touching your own mouth, nose, or eyes.
More Information About the Flu from Johns Hopkins Medicine
Ask the Expert
Each year, between 5 to 20 percent of Americans get the flu, sending many to the hospital with severe complications. Learn how you and your loved ones can stay healthy with answers from internal medicine physician Michael Albert.
What are the symptoms of the flu?
Each person may experience symptoms differently. The flu is called a respiratory disease, but it can affect your entire body. People usually become very sick with several, or all, of the following symptoms:
Fever and body aches usually last for 3 to 5 days, but cough and fatigue may last for 2 weeks or more.
The symptoms of the flu may look like other medical problems. Always talk your healthcare provider for a diagnosis.
How is the flu diagnosed?
The flu is diagnosed based on your symptoms. Lab tests may be used to confirm the diagnosis, if necessary.
How is the flu treated?
Specific treatment for the flu will be determined by your healthcare provider based on:
Your age, overall health, and medical history
Extent and type of flu, and severity of symptoms
How long you’ve had symptoms
Your tolerance for specific medicines, procedures, or therapies
Expectations for the course of the disease
Your opinion or preference
The goal of treatment for the flu is to help prevent or decrease the severity of symptoms. Treatment may include:
Antiviral medicines. They can reduce how long you’ll have the flu, but they can’t cure it. They have to be started within the first 2 days of the illness. These medicines do have some side effects, such as nervousness, lightheadedness, or nausea. These medicines are prescribed by a doctor.
Medicines. There are medicines for congestion and nasal discharge. You can also take medicine to relieve aches and fever. Do not give aspirin to children with fever. The drug of choice for children is acetaminophen.
Rest. Bed rest and increased intake of fluids.
Talk with your healthcare provider for more information.
What are the complications of the flu?
The most common complication of the flu is pneumonia. It can also cause serious muscle and central nervous system complications. Of those who get the flu, between 3,000 and 49,000 will die from it or from complications. Most of these deaths happen in people ages 65 and older.
Can the flu be prevented?
A new flu vaccine is made each fall. Everyone ages 6 months and older should get a flu shot each year. It is usually recommended for specific groups of people, as well as for anyone who wants to avoid having the flu.
The flu shot is safe. The CDC and the FDA closely watch vaccine safety. Hundreds of millions of flu vaccines have been safely given across the country for decades.
The flu shot can’t give you the flu. The most common side effects from a flu shot are:
If you have them at all, these side effects are usually mild and last a short time.
The effectiveness of the vaccine varies from one person to another. It can depend on factors such as age and overall health.
The following may also be helpful for preventing the flu:
When possible, avoid or limit contact with sick people.
Wash your hands frequently to reduce the risk of infection.
Cover your nose and mouth when coughing or sneezing to limit spread of the virus.
The flu causes complications that may develop into a more serious disease or become dangerous to some people. This includes older adults and those with chronic medical problems. Always talk with your healthcare provider to find out if you should receive the flu shot.
Although the flu shot is safe, some people should NOT be vaccinated. These include:
People who are allergic to eggs
People who have had a severe reaction in the past after getting the flu shot
People who are sick with a fever (these people should get vaccinated after they have recovered)
Babies who are age 6 months old or younger
People who have a history of Guillain-Barré syndrome, a severe paralyzing illness, after getting the flu shot
The CDC recommends getting the flu shot every year, as soon as it becomes available in your community. Flu season can begin as early as October and most commonly peaks in the U.S. in January or February, but flu seasons are unpredictable. The flu shot takes 1 to 2 weeks to become effective.
The CDC recommends that travelers have the flu vaccine at least 2 weeks before planned travel to allow time to develop immunity. Talk with your healthcare provider for more information.
More Information About Flu from Johns Hopkins Medicine
Anesthesia May Help with Flu Treatment Shortages
Inhaled anesthetics have made modern surgery possible. Now, researchers at Johns Hopkins and elsewhere have added to evidence that certain anesthetics — routinely used during surgeries — may also possess powerful effects on the immune system that can combat viral and bacterial infections in the lung, including influenza and pneumonia.
When should I call my healthcare provider?
For most people, the flu can be treated at home without treatment from your healthcare provider. However, if your condition or situation makes you more susceptible to complications from the flu, tell your healthcare provider when you suspect you have the flu. If your symptoms get worse or you have new symptoms, let your healthcare provider know.
Key points about the flu
The flu is an easily spread viral respiratory tract infection.
The flu is caused by viruses that are generally passed from person to person through the air.
The flu is treated with bedrest, increased fluid intake, and medicines to treat discomfort and fever
Antiviral medicines taken within the first 2 days of illness can reduce the length and severity of the disease but does not cure it.
Getting the flu shot every year is the best prevention.