Flu symptoms: Understanding the illness and when to see a healthcare provider
Medically reviewed by Dr. Betsy Koickel, MD on October 6, 2026.
Key takeaways:
- Flu symptoms often come on suddenly and include fever, chills, cough, body aches, headache and fatigue, with most people recovering at home within one to two weeks.
- Knowing when to go to a healthcare provider for flu symptoms can help prevent complications, especially if you develop trouble breathing, worsening symptoms or are at high risk for severe illness.
- Because the flu and COVID-19 share many symptoms, getting a prompt flu diagnosis can help you get the care you need.
Every year, rates of influenza in the U.S. begin to rise in November, peak between January and February and start to decline in March. According to the Centers for Disease Control and Prevention (CDC), the 2024–2025 flu season resulted in an estimated 51 million illnesses, 23 million healthcare visits, 710,000 hospitalizations and 45,000 deaths.
Now that we’re about to enter flu season, rates of influenza are beginning to climb again. It’s essential to be aware of flu symptoms, including fever, chills, cough, body aches, headache and fatigue. You should also be aware of warning signs that require medical attention and the difference between a virus and bacteria. Here are some ways you can be more prepared for flu season this year.
What are common flu symptoms?
Flu symptoms often come on suddenly and can range from mild to severe. Common symptoms include:
- Body aches or muscle pain
- Chills
- Cough
- Fatigue
- Fever or feeling feverish
- Headache
- Runny or stuffy nose
- Sore throat
- Vomiting or diarrhea, which are more common in children than adults
It's also good to be mindful that flu symptoms and COVID-19 symptoms, such as low-grade fever, nasal congestion and sore throat, can be the same thing.
When to go to a provider for flu symptoms?
Most people with the flu recover at home within a week or two with rest, fluids and over-the-counter medications. But if you get tested early for the flu a provider can prescribe antiviral medications that can help you get better faster.
However, some people develop more severe illness and may need medical care. You should consider seeing a healthcare provider if your flu symptoms are severe, aren't improving after several days or begin to worsen after initially getting better.
Some of situations where you may need additional care might include:
1. You are under 2 years old or over 65
Young children and older adults are at a higher risk of severe flu-related complications than other age groups. Children under age 2 do not have a fully mature immune system, which predisposes them to many illnesses. They are also more prone to dehydration due to their smaller body size.
Children under 6 months are at exceptionally high risk because they are too young to receive a flu shot. Parents should know when to see a healthcare provider for flu symptoms, especially if a young child has difficulty breathing, signs of dehydration or symptoms that are getting worse.
Older adults are at a higher risk of severe flu because they often have a weakened immune system due to their age. The flu can also worsen the underlying medical conditions many seniors have, including diabetes and heart and lung disease. Seniors are also at risk for dehydration, as they don’t feel thirst in the same way as younger people do.
2. You have shortness of breath
A persistent dry cough is a common flu symptom, but shortness of breath signals a serious issue needing prompt medical care. Difficulty breathing with the flu can point to viral or bacterial pneumonia, respiratory distress or other cardiac and respiratory complications.
If you have shortness of breath, a detailed evaluation by a healthcare provider is warranted. This exam includes a measurement of your oxygen saturation and other vital signs, a lung exam and, in some cases, a chest X-ray. If you experience severe symptoms of breathing difficulty, like lips turning blue, chest pain, lethargy or confusion, these are emergency warning signs of the flu, and you should seek immediate medical attention.
3. You have persistent vomiting or diarrhea
Vomiting and diarrhea are common flu symptoms, especially for children, but people of any age can experience this. If these symptoms persist, they can lead to dehydration and electrolyte imbalances. Anyone with persistent gastrointestinal symptoms should see a healthcare provider for next steps.
4. Your symptoms last more than two weeks
A viral infection should run its entire course within 10-14 days, with a mild cough sometimes lasting slightly longer. If your symptoms persist beyond 14 days or seem to be getting worse, it’s essential to seek medical attention to see if there’s another underlying cause that requires further evaluation or treatment.
5. You have underlying health conditions
For those with underlying health conditions, a flu diagnosis can not only cause flu symptoms; it can also worsen pre-existing conditions, including asthma, diabetes, heart disease, kidney disease and chronic lung disease. These conditions also put you at greater risk for more severe symptoms if you do get the flu.
Pregnancy may complicate a flu diagnosis; therefore, pregnant women should seek care for any concerning symptoms. Additionally, pregnant women should get a flu shot during flu season, as flu complications can affect both mom and baby. The mother’s immunity passes through the placenta, providing antibodies to newborns who cannot yet receive the vaccine but may be born during flu season.
6. Your symptoms suddenly worsen
One of the risks of viral infections is that they can lead to secondary bacterial infections. These infections happen for two primary reasons. First, the body’s immune system is weakened from fighting the virus, so it’s more susceptible to other pathogens. And second, the mucus membranes in the upper and lower respiratory tracts are inflamed, making them easier for bacteria to penetrate.
Common secondary infections in influenza patients include sinusitis, pneumonia, sepsis and meningitis. If you seem to be recovering from the flu but suddenly develop a fever or worsening symptoms, it’s wise to seek medical attention to see if antibiotics are warranted.
7. You have COVID-19 symptoms
COVID-19 and influenza are both respiratory viruses, so many COVID and flu symptoms overlap. These shared symptoms include a fever, cough, headache, nasal congestion, body aches, fatigue and diarrhea.
Although COVID-19 has generally caused higher rates of hospitalization and death than seasonal influenza, the difference has narrowed as population immunity and treatments have improved.
Symptomatic patients often benefit from rapid flu and rapid COVID-19 tests, which can determine a diagnosis, inform a patient’s treatment plan and decrease their risk of spreading an infection to the people around them.
If you are wondering if you should go to a healthcare provider for the flu, we are here to help. The urgent care centers can help you get the correct diagnosis and treatment, whether you have the flu, COVID-19 or are just not feeling your best. To get started, find a center near you and walk in or save your spot online.
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