Flu

What is Flue or Influenza?

is a respiratory illness that results from a viral infection. Flu is highly contagious and spreads through respiratory droplets. A person can pass it on while talking or through physical contact, such as shaking hands.

Influenza A and influenza B cause seasonal epidemics in the United States and elsewhere every winter. Type C usually causes mild respiratory illness.

Some strains of influenza A, such as the H5N1 “bird flu” virus, occasionally infect humans, causing serious illness. Experts track these strains carefully, as they try to predict how they will change, and how they might affect people.

In this article, we explain the symptoms of flu, the treatment options, how it differs from a cold, and how to prevent the flu.

Symptoms

According to the Centers for Disease Control and Prevention (CDC), a person with flu may experienceTrusted Source:

a high temperature that lasts 3–4 days
a stuffy or runny nose
cold sweats and shivers
aches that may be severe
a headache
fatigue

Not everyone with flu will have all of these symptoms. For instance, it is possible to have flu without a fever.

The symptoms of influenza typically come on suddenly. Initially, a person with flu mayTrusted Source experienceTrusted Source:

a high temperature
a stuffy or runny nose
a dry cough
cold sweats and shivers
aches that may be severe
a headache
fatigue, and a feeling of being unwell
a low appetite

Why do people sometimes have chills but no fever?

Flu symptoms in adults

Adults with the following symptoms should seek medical helpTrusted Source urgently:

breathing difficulties
pain or pressure in the chest or abdomen
dizziness, confusion, or loss of alertness
seizures
not urinating, which may indicate dehydration
severe pain, weakness, and unsteadiness
a fever or cough that goes away and then comes back
a worsening of other existing health conditions

Flu symptoms in children

Children often have similar symptoms to adults but can also have gastrointestinal symptoms, such as nausea, vomiting, and diarrhea.

If a child has the following symptoms, they need emergency medical care:

breathing difficulties
rapid breathing
bluish face or lips
chest pain or ribs pulling inward as they breathe
severe aches
dehydration, for example, not urinating for 8 hours and crying dry tears
lack of alertness or interaction with others
a fever above 104°F or any fever in a child under 12 weeks of age
a fever or cough that goes away but then comes back
a worsening of any other medical conditions

Should children have flu medication? Find out more here about Tamiflu and its effects on children.

Flu symptoms in babies

Flu can be dangerous for babies. If symptoms appear, a parent or caregiver should seek medical help.

A baby with flu may:

be very tired
have a cough and sore throat
have a stuffy or runny nose
have a fever of 100°F or more
have vomiting or diarrhea

The baby needs emergency medical attention if they:

do not want anyone to hold them
have a blue or gray skin color
are breathing fast or have difficulty breathing
have a fever with a rash
have symptoms that go away but come back again
show signs of dehydration, for example, not urinating
do not wake up or interact
have severe and persistent vomiting

What happens when a baby gets a cold?

Flu type A symptoms

If a person has the following symptoms, they may have influenza type A:

fever and chills
headache
muscle aches
fatigue
weakness
a stuffy or runny nose
a sore throat and cough

Flu type B symptoms

Influenza B symptoms are similar to those of influenza A.

Causes

Flu viruses travel through the air in droplets when someone with the infection coughs, sneezes or talks. You can inhale the droplets directly, or you can pick up the germs from an object — such as a telephone or computer keyboard — and then transfer them to your eyes, nose or mouth.

People with the virus are likely contagious from the day or so before symptoms first appear until about five days after symptoms begin. Children and people with weakened immune systems may be contagious for a slightly longer time.

Influenza viruses are constantly changing, with new strains appearing regularly. If you’ve had influenza in the past, your body has already made antibodies to fight that particular strain of the virus. If future influenza viruses are similar to those you’ve encountered before, either by having the disease or by getting vaccinated, those antibodies may prevent infection or lessen its severity.

But antibodies against flu viruses you’ve encountered in the past can’t protect you from new influenza strains that can be very different immunologically from what you had before.

Risk factors

Factors that may increase your risk of developing influenza or its complications include:

Age. Seasonal influenza tends to target children younger than 12 months of age and adults 65 years old or older.
Living or working conditions. People who live or work in facilities with many other residents, such as nursing homes or military barracks, are more likely to develop influenza. People who are hospitalized are also at higher risk.
Weakened immune system. Cancer treatments, anti-rejection drugs, long-term use of steroids, organ transplant, blood cancer or HIV/AIDS can weaken your immune system. This can make it easier for you to catch influenza and may also increase your risk of developing complications.
Chronic illnesses. Chronic conditions, including lung diseases such as asthma, diabetes, heart disease, neurological or neurodevelopmental disease, an airway abnormality, and kidney, liver or blood disease, may increase your risk of influenza complications.
Aspirin use under age 19. People who are younger than 19 years of age and receiving long-term aspirin therapy are at risk of developing Reye’s syndrome if infected with influenza.
Pregnancy. Pregnant women are more likely to develop influenza complications, particularly in the second and third trimesters. Women who are up to two weeks postpartum also are more likely to develop influenza-related complications.
Obesity. People with a body mass index (BMI) of 40 or more have an increased risk of complications from the flu.

Complications

If you’re young and healthy, seasonal influenza usually isn’t serious. Although you may feel miserable while you have it, the flu usually goes away in a week or two with no lasting effects. But children and adults at high risk may develop complications such as:

Pneumonia
Bronchitis
Asthma flare-ups
Heart problems
Ear infections

Pneumonia is the most serious complication. For older adults and people with a chronic illness, pneumonia can be deadly.

Controlling the spread of infection

The influenza vaccine isn’t 100 percent effective, so it’s also important to take measures such as these to reduce the spread of infection:

Wash your hands. Thorough and frequent hand-washing is an effective way to prevent many common infections. Or use alcohol-based hand sanitizers if soap and water aren’t readily available.
Contain your coughs and sneezes. Cover your mouth and nose when you sneeze or cough. To avoid contaminating your hands, cough or sneeze into a tissue or into the inner crook of your elbow.
Avoid crowds. The flu spreads easily wherever people congregate — in child care centers, schools, office buildings, auditoriums and public transportation. By avoiding crowds during peak flu season, you reduce your chances of infection. And if you’re sick, stay home for at least 24 hours after your fever subsides so that you lessen your chance of infecting others.

Treatment

Most people will be able to treat the flu at home. A combination of lifestyle remedies and over-the-counter medication can help relieve symptoms.

Pain relief medication can help manage a headache and body pains. A healthcare professional can recommend the best options.

Some painkillers, such as aspirin, are not suitable for children under 16 years of age. The use of aspirin at this age can lead to a condition known as Reye’s syndrome.

Various options are available over the counter or to purchase online. It is important to compare different products and only take them under the advice of a medical professional.

How long does flu last? Find out here.

Flu medication

A virus causes flu, so antibiotics will not cure the illness. A doctor will only prescribe antibiotics if a bacterial infection is present alongside the flu. However, antiviral medications may help when someone has the flu.

Here are some tips on how to treat a cold or flu at home.

Antivirals aim to stop the virus from multiplying in a person’s body. Examples include oseltamivir (Tamiflu) and zanamivir (Relenza).

In 2018, the Food and Drug AdministrationTrusted Source (FDA) approved a new drug called baloxavir marboxil (Xofluza) for acute, uncomplicated flu. People can take the drug by mouth in a single dose.

People can receive this treatment if they are aged 12 years or more and have had symptoms for fewer than 48 hours. Possible side effects include diarrhea and bronchitis.

Some research shows that flu medication may affect a person’s heart. Find out more here.

Flu home remedies

When a person has flu, it is essential that they:

stay at home
avoid contact with other people if possible
keep warm and rest
consume plenty of liquids and healthful foods
avoid alcohol
stop smoking, as this raises the risk of complications

Other things people can try at home includeTrusted Source:

chicken broth
herbal teas
vitamin supplements

However, there is not enough evidence available to confirm that consuming these helps.

Which foods are a good choice for a person with flu?

Prevention

The Centers for Disease Control and Prevention (CDC) recommends annual flu vaccination for everyone age 6 months or older.

Each year’s seasonal flu vaccine contains protection from the three or four influenza viruses that are expected to be the most common during that year’s flu season. This year, the vaccine will be available as an injection and as a nasal spray.

In recent years, there was concern that the nasal spray vaccine wasn’t effective enough against certain types of flu. However, the nasal spray vaccine is expected to be effective in the 2019-2020 season. The nasal spray still isn’t recommended for some groups, such as pregnant women, children between 2 and 4 years old with asthma or wheezing, and people who have compromised immune systems.

Most types of flu vaccines contain a small amount of egg protein. If you have a mild egg allergy — you get hives only from eating eggs, for example — you can receive the flu shot without any additional precautions. If you have a severe egg allergy, you should be vaccinated in a medical setting and be supervised by a doctor who is able to recognize and manage severe allergic conditions.

Flu diagnosis

If a person seeks medical advice for flu symptoms, a doctor will likely ask about their symptoms and do a physical examination. A doctor may also take a throat swab for testing.

The rapid influenza diagnostic testTrusted Source can produce results in 10–15 minutes but may not be accurate. Other, more accurate tests can take longer to give results.

How Serious Is Flu?

Most people who get the flu feel much better in a week or two. But, some people can get very sick. For example, because your body is busy fighting off the flu, you might pick up a second infection. Older people are at great risk of these secondary infections, such as pneumonia.

How Does Flu Spread?

The flu is contagious—that means it spreads from person to person, often through the air. You can pass on the infection before you feel sick. You are contagious for several days after you get sick. You can catch the flu when someone near you coughs or sneezes. Or, if you touch something the virus is on, like Ellen and Jack’s phone or doorknob, and then touch your nose or mouth, you could catch the flu. The flu virus can live on a surface like a book or doorknob for a number of hours. Remember to wash your hands often when you are around someone who is sick. Make a point of washing them before eating or touching your eyes, nose, or mouth. If you can, stay away from sick people. That will help stop the flu from spreading.

Is It the Flu or a Cold?

It’s easy to confuse a common cold with seasonal flu. A cold is milder than the flu, but since the flu can make older people very sick, you should know the difference. That way you will know when to call the doctor, who might want to give you a prescription for medicines that can help you get over the flu.

People with the flu can have fever, chills, dry cough, general aches and pains, and a headache. They feel very tired. Sore throat, sneezing, stuffy nose, or stomach problems are less common. What some people call “stomach flu” is not influenza.

When Should I Get My Flu Shot?

Most people get the flu between December and March. That’s why that time is called the flu season. The timeframe can vary each year. It takes at least 2 weeks for your shot to start working, so try to get your flu shot by the end of October. Don’t worry if you can’t get your flu shot before the flu season starts. The shot can help keep you healthy no matter when you get it.

Why Do You Need a Flu Shot Every Year?

You need a flu shot every year for two reasons. First, flu viruses change. Each year’s virus may be just a little different. If the virus changes, the vaccine used in the flu shot is changed. Second, the protection you get from a flu shot lessens with time, especially in older people. So, you should get the shot every fall to do your best to stay protected from the flu.

Are There Side Effects?

Most people have no problem with a flu shot. In fact, for most people, the flu is far more dangerous than the flu shot.

When you get the flu shot, your arm might be sore, red, or a bit swollen. These side effects may start shortly after getting the shot and can last up to 2 days. They should not get in the way of your daily activities. A few people do have a headache or a low-grade fever for about a day after they get the shot. The flu shot cannot cause you to get the flu.

If you are allergic to eggs, you can usually get the flu shot. However, if you have ever had a severe allergic reaction to a flu shot, you should not get a new flu shot.