Flu (Influenza)

The flu comes on fast and can flatten you for a week or more. Knowing what to watch for helps you decide whether to rest at home or get checked.

What Is It

Influenza, or the flu, is a virus that infects the nose, throat, and lungs. Two main types circulate each winter, flu A and flu B. Both can make you feel very sick, and neither one is reliably milder than the other. In Illinois, flu season usually runs from October through March and peaks around December and February.

Symptoms

The flu usually starts suddenly. You feel fine in the morning and awful by evening. Common symptoms include fever or chills, body aches, headache, dry cough, sore throat, and deep tiredness. Children may also have nausea or vomiting. You can have the flu without a fever, so a normal temperature does not rule it out. Most people start to feel better in five to seven days, though a cough and low energy can hang on for two weeks or longer. You are generally contagious from about a day before symptoms start through about five to seven days after.

Treatment

A rapid flu swab can usually confirm the diagnosis during your visit. If you are seen in the first 48 hours, an antiviral medicine such as oseltamivir (Tamiflu) may shorten the illness by about a day and may lower the chance of complications. It works best when started early. Antibiotics do not treat the flu because the flu is a virus, though they are sometimes needed if a bacterial infection such as pneumonia develops on top of it. For most people, rest, fluids, and over the counter fever reducers are enough. An annual flu shot remains the best way to lower your risk, and getting one partway through the season is still worthwhile.

When to Come In vs ER

Come to Urgent Care	Go to the Emergency Room
Fever, body aches, and cough that started in the last day or two	Trouble breathing or shortness of breath at rest
You want a rapid flu test	Chest pain or pressure
Fever lasting more than three days	Confusion, or hard to wake up
You started to improve, then got worse again	Bluish lips or face
Cough and chest congestion while still able to eat and drink	Severe dehydration, such as no urination, dizziness when standing, or no tears in a child
You are higher risk and symptoms just started, including adults over 65, pregnant patients, young children, and people with asthma, diabetes, heart disease, or a weakened immune system	A seizure, or a fever in an infant under three months

FAQ

How long does the flu last?

Most people feel better within five to seven days. Cough and fatigue often last longer.

How long are you contagious with the flu?

Usually from about a day before symptoms begin until about five to seven days after. Children can spread it longer.

What is the difference between flu A and flu B?

They are different strains of the same family. Flu A is more common in adults and drives most large outbreaks, but flu B can be just as unpleasant, especially in children.

Can you have the flu without a fever?

Yes. Some people, including older adults, never run a fever even with a confirmed flu test.

If your symptoms started in the last day or two, come in for a rapid test while an antiviral can still make a difference.

Medically reviewed by Rodion Levin, MSN, FNP-C, Medical Director, Vitality Urgent Care.

Frequently Asked Questions (FAQ)

Flu Virus (Influenza)

How does the flu spread?

Flu spreads mainly through droplets when an infected person coughs, sneezes, or talks. You can also catch the flu by touching contaminated surfaces and then touching your face. Vitality Urgent Care recommends frequent handwashing and avoiding close contact with sick individuals to help reduce the spread of flu.

How long is the flu contagious?

People with the flu are usually contagious from about one day before symptoms begin to around 5 to 7 days after becoming sick. Children and people with weakened immune systems may stay contagious longer.

How effective is the flu vaccine?

The flu vaccine is updated each year to match expected influenza strains. While it may not prevent every case, it can reduce symptom severity and lower the risk of serious complications. Vitality Urgent Care offers flu shots to help protect you and those around you.

What treatment options are available for the flu?

If diagnosed early, often within the first 48 hours, antiviral medications such as oseltamivir may help shorten the illness and reduce symptoms. Many people improve with rest, hydration, and over the counter symptom relief. Vitality Urgent Care offers flu testing and personalized treatment recommendations.

Can the flu lead to complications?

Yes. The flu can lead to serious complications, especially in young children, older adults, pregnant women, and people with chronic medical conditions. Possible complications include pneumonia, bronchitis, sinus infections, and worsening of underlying health problems.

How can you tell the difference between a cold and the flu?

The flu often starts suddenly and commonly causes fever, body aches, and significant fatigue. A cold usually develops more gradually and tends to cause milder symptoms. Vitality Urgent Care offers rapid flu testing to help identify the cause of your symptoms.

What are the best ways to prevent the flu?

The best ways to help prevent the flu include getting vaccinated every year, washing your hands often, avoiding close contact with sick individuals, covering coughs and sneezes, and disinfecting commonly touched surfaces. Vitality Urgent Care offers flu shots and prevention guidance during flu season.

When is flu season?

In the United States, flu season usually peaks between December and February, though cases can begin in October and continue through May. Getting a flu shot early can help you prepare before flu activity increases.

Should I visit urgent care if I have flu symptoms?

If you have flu symptoms such as fever, body aches, cough, fatigue, or other concerns, visiting Vitality Urgent Care can help you get evaluated quickly. Rapid flu testing and treatment options may help manage symptoms and reduce the risk of complications.