Flu Symptoms and Treatment

Flu symptoms and treatment are a high priority in fall and winter when the highly contagious influenza virus quickly spreads. However, you can significantly lower your risk and prevent illness by getting a flu shot early in the season (October).

Seasonal flu is highly contagious, often spreading before an infected person recognizes symptoms like a sore throat, cough, congestion, and body aches. Seeking antiviral flu treatment within a few days of symptoms can shorten your illness.

Flu Symptoms

Flu symptoms can vary from person to person. For example, some people will develop a fever with the flu, while others will not. Your symptoms can be mild to severe, depending on your age, overall health, and the strain of the virus.

The most common flu symptoms include:

• Fever
• Chills
• Body aches
• Sore throat
• Cough
• Headaches
• Fatigue
• Congestion
• Runny nose

Digestive symptoms, like vomiting and diarrhea, are more likely to occur among children than adults with the flu.

Warning Signs You Need Medical Care

These symptoms are warning signs that your respiratory infection needs immediate medical care:

• Difficulty breathing (shortness of breath, fast breathing, ribs pulling in with each breath)
• Bluish lips or face
• Chest pain
• Abdominal pain
• Severe muscle pain
• Severe weakness
• Confusion
• Dizziness
• Seizures
• Dehydration (not urinating for eight hours, dry mouth)
• Any fever in children younger than three months
• Fever above 104 degrees Fahrenheit
• Worsening of chronic medical conditions 

Flu vs. Cold vs. COVID-19

The flu, colds, and COVID-19 are all caused by viruses that can result in respiratory symptoms. Depending on the severity of your symptoms, it can be challenging to determine which one you have without taking a test.

The table below outlines the main differences between the flu, cold, and COVID-19 symptoms.

What Causes the Flu?

The flu is a respiratory infection caused by two viruses, influenza A and influenza B. The viruses pass between humans and, in some cases, from animals to humans. The viruses can spread fast across the globe, especially flu A.

Flu A vs Flu B

Though there are four flu viruses—A, B, C, and D—but influenza A and B are the two primarily affecting people. Influenza C only causes mild infections in people, and influenza D primarily affects cattle. Only influenzas A and B are known to cause flu pandemics and regularly cause seasonal epidemics every winter.

Influenza A and B are treated the same way and can have similar symptoms, but they have some differences in how they affect people.

Flu A is more common, responsible for approximately 75% of all flu cases experienced yearly. This is likely because it mutates (changes) quickly, allowing it to transfer from animals and birds to humans, and then between people. Frequent viral mutation also means that new vaccines are needed every year to keep up with new flu A strains.

Influenza A is the only type of flu that causes pandemics. It can affect adults and children but tends to be more severe in adults.

Flu B only affects humans and, more commonly, infects children. While it usually has mild symptoms, it can have more severe effects on kids under age 5.

How the Flu Spreads

Influenza A and B are transmitted (spread) when someone with the virus sneezes or coughs, sending tiny virus-containing droplets into the air. Anyone nearby who inhales the droplets and takes in the virus can get sick.

The virus can also live for a time on surfaces. If one person sneezes or coughs the droplets may land on a surface. Or, a person with a flu infection may sneeze into their hand, and then touch an object. In both cases, the virus spreads to people who touch the area before the virus dies.

When Is Flu Season?

Flu season runs from October through May. However, cases typically peak between December and March, with the most illnesses frequently reported in February.

Though flu viruses circulate all year long, flu season occurs in the fall and winter because of cooler temperatures. In colder months, the influenza viruses thrive longer, natural defenses are down, and transmission between people increases.

Complications and Risks

Most people will recover from the flu within a few days to two weeks. Unfortunately, some people develop flu complications, which can become life-threatening.

Flu often causes ear and sinus infections. Some people develop serious health complications, such as pneumonia (a lung infection), and heart inflammation (myocarditis).

Though rare, flu may also cause inflammation of the brain (encephalitis) or muscles (myositis). In some cases, a flu infection can lead to multi-organ failure or an extreme whole-body inflammatory response called sepsis.

If you have a chronic health condition, the flu can make your symptoms worsen. For instance, the flu can lead to more severe asthma attacks among people who already have this respiratory condition.

Your risk of developing complications is higher if you:

• Are 65 and older
• Are younger than 5 years old
• Are pregnant
• Have asthma, COPD, or any chronic lung condition
• Have kidney, liver, blood vessel, heart or neurological disease
• Have a condition making it difficult to swallow or cough
• Have a blood disorder, such as sickle cell disease
• Have a weakened immune system
• Are under 19 years old and taking aspirin regularly
• Are living in a long-term care facility
• Are obese

How Is the Flu Diagnosed?

Your healthcare provider will ask about your symptoms and how long you've been sick. They'll also look in your ears, nose, and throat and listen to your lungs with a stethoscope.

If flu activity is high in your area and your symptoms point to influenza, your healthcare provider may diagnose and treat you based on your physical assessment and after eliminating other reasons for your symptoms.

Your provider may also perform a flu test to determine if your symptoms are definitely due to the influenza virus. The flu test is especially useful when flu activity is low in your area but your healthcare provider still thinks you might have it.

An in-office rapid influenza test takes about 15 minutes to get results. The test typically involves a nasal or throat swab to determine whether you have the flu virus.

Flu Treatment

If you become sick with the flu virus, there are some measures you can take to help speed up your recovery as you ride the illness out.

Antiviral medications may help reduce the duration of symptoms and prevent flu complications if you start taking them within the first few days of symptoms. Visit your healthcare provider as soon as symptoms begin to get a prescription.

Otherwise, the best thing for you to do if you have the flu is to stay home and rest. Avoid contact with others unless you require medical care. If you're in a high-risk group or develop warning signs, seek medical attention immediately.

Try to stay isolated (away from other people) until you are fever-free and without other symptoms for 24 hours. If you need to be around others, wear a mask to help prevent the spread of germs.

How Long Does the Flu Last?

For most healthy people, symptoms of the flu go through stages, subsiding within a few days to two weeks. For people who are in a high-risk group or have other existing medical conditions, the flu may take longer to heal.

How Long Is the Flu Contagious?

If you pick up the flu virus, you can give it to someone else one day before your symptoms begin and up to seven days after they improve. The most contagious period is the first three to four days after you start feeling sick.

Prevention

The most effective way to prevent flu is getting an annual flu shot. While the most prominent circulating flu virus strains change yearly, scientists do their best to predict which ones will be the most contagious using research. Annual vaccines are designed around these data.

Regardless, all flu vaccines in the United States protect you against three different flu viruses. These include an influenza A (H1N1) virus, an influenza A (H3N2) virus, and an influenza B virus.

Flu shots work by causing your body to produce antibodies within two weeks of receiving the shot. These antibodies fight off the flu virus after you're exposed.

A healthcare provider can answer any questions about the flu shot and determine which one is best for you, especially if you are over 65. Older individuals are at a higher risk for complications from the flu. They should receive a higher dose or an adjuvanted flu vaccine that contains an ingredient to produce a better immune response.

The best time to get your flu shot is in September or October, so your body has time to prepare antibodies before peak flu season arrives. Annual flu shots are available at many pharmacies, grocery stores, and primary care offices.

Summary

The flu virus causes mild to severe symptoms that usually appear suddenly. The most common flu symptoms include fever, body aches, fatigue, sore throat, cough, headache, congestion, and a runny nose. Symptoms such as difficulty breathing, chest pain, confusion, and severe weakness are signs of a developing complication that needs immediate medical attention.

Your healthcare provider can prescribe antiviral medication to help you feel better faster. However, you must see your provider in the first few days after your symptoms appear. Other than antiviral medication, the only flu treatment is self-care. You should rest, drink plenty of fluids, and take over-the-counter medications to relieve symptoms.