Key Points
- Flu season most often peaks in fall and winter, with timing varying each year.
- Influenza is a contagious viral respiratory illness that can be mild or severe.
- Some groups face higher risks of complications.
- Vaccination and basic hygiene reduce the risk of serious illness.
- Certain warning signs require urgent or emergency medical care.
Introduction
Flu season refers to the time of year when influenza spreads more widely and causes increased illness. Influenza (the flu) is a contagious respiratory illness caused by influenza viruses that primarily affect the nose, throat, and lungs. Illness can range from mild to severe, and some people are at higher risk of complications. This article presents verified, evidence-based information on flu season, symptoms, prevention, treatment, and when to seek medical care.
Understanding the Flu
What Is the Flu (Influenza)?
The flu is a viral respiratory illness. It differs from the common cold in typical severity and the risk of complications. While many people recover within about one to two weeks, influenza can cause serious illness and, in some cases, death.
When Is Flu Season?
In the United States, flu activity most commonly increases in the fall, peaks during winter, and declines in the spring. The exact timing varies from year to year.
How the Flu Spreads
Transmission
Influenza viruses spread mainly through respiratory droplets released when an infected person coughs, sneezes, or talks. Transmission can also occur when a person touches a contaminated surface and then touches their mouth, nose, or eyes.
When You’re Contagious
People with the flu can spread the virus:
- About one day before symptoms begin
- For five to seven days after becoming sick
Children and people with weakened immune systems may remain contagious for longer.
Flu Symptoms
Common Symptoms
Flu symptoms usually begin suddenly and may include:
- Fever or chills
- Cough
- Sore throat
- Runny or stuffy nose
- Muscle or body aches
- Headache
- Fatigue
In children, nausea, vomiting, and diarrhea can also occur.
Flu Compared With Other Illnesses
Flu vs. Common Cold
Compared with the common cold:
- Flu symptoms tend to be more severe
- Flu symptoms usually start abruptly
- Fever, body aches, and marked fatigue are more common with flu
Flu Complications and Risk
Possible Complications
Most people recover without complications. However, influenza can lead to:
- Pneumonia
- Ear infections
- Sinus infections
- Worsening of chronic medical conditions (such as asthma, heart disease, or diabetes)
Who Is at Higher Risk?
People at increased risk of severe illness or complications include:
- Adults aged 65 years and older
- Young children
- Pregnant individuals
- People with chronic medical conditions
- People with weakened immune systems
Treatment Overview
Home Management
Many people with mild flu illness recover at home without medical care.
Antiviral Medications
Prescription antiviral medications may be recommended for some people, especially those at higher risk, those who are severely ill, or those who are hospitalized. These medicines work best when started within 48 hours of symptom onset, though they may still help in some cases when started later.
Antibiotics
Antibiotics do not treat the flu because influenza is caused by a virus. They are used only if a bacterial complication is diagnosed.
Prevention and Risk Reduction
Flu Vaccination
Annual flu vaccination is one of the most effective ways to reduce the risk of flu illness and serious complications. Flu vaccines are updated each year to match circulating virus strains. Vaccination does not prevent all flu cases, but it reduces the risk of severe illness, hospitalization, and death.
Reducing Spread
Evidence-based steps to reduce transmission include:
- Washing hands frequently
- Avoiding close contact with people who are sick
- Cleaning frequently touched surfaces
- Staying home when sick
When to See a Doctor
Seek Medical Care Promptly If:
- You have flu symptoms and are at higher risk for complications
- Symptoms are severe or rapidly worsening
Emergency Warning Signs in Adults
Seek emergency care for:
- Difficulty breathing or shortness of breath
- Chest pain or pressure
- Ongoing dizziness or confusion
- Symptoms that improve but then return with fever or worsening cough
Emergency Warning Signs in Children
Seek emergency care if a child has:
- Trouble breathing
- Bluish or gray lips or nail beds
- Signs of dehydration
- Symptoms that improve but then worsen
Frequently Asked Questions
Can the flu cause a sinus infection?
Yes. Sinus infections are a recognized complication that can occur during or after influenza.
How long does the flu usually last?
Most people recover within about one to two weeks, though recovery time can vary.
Is the flu contagious before symptoms appear?
Yes. People can spread the flu about one day before symptoms begin.
Does the flu shot prevent all flu cases?
No. Flu vaccines do not prevent all cases, but they significantly reduce the risk of severe illness and complications.
How long does the flu last?
Most people begin to feel better within one to two weeks.
Is the flu contagious before symptoms?
Yes. Transmission can occur before a person realizes they are sick.
Can you get a sinus infection from the flu?
Yes. Sinus infection is a known complication of influenza.
When should you seek emergency care for flu?
Emergency care is needed for breathing problems, chest pain, confusion, or symptoms that worsen after initial improvement.
How can you tell the difference between flu and sinus infection?
There is no high-quality evidence supporting a simple, symptom-only method to reliably distinguish flu from sinus infection without medical evaluation.
APA References List
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Centers for Disease Control and Prevention. (2024, August 26). Signs and symptoms of flu. https://www.cdc.gov/flu/signs-symptoms/index.html
Centers for Disease Control and Prevention. (2024, September 17). How flu spreads. https://www.cdc.gov/flu/spread/index.html
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Centers for Disease Control and Prevention. (2024, August 8). Clinical signs and symptoms of influenza (for health professionals). https://www.cdc.gov/flu/hcp/clinical-signs/index.html
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