Dangerous Flu Symptoms You Should Never Ignore

Be aware of dizziness, trouble breathing and other signs you need medical attention.

Woman with the flu blowing her nose into a tissue

Medically reviewed in September 2022

Updated on September 28, 2022

Most cases of the flu are a nuisance—you’ll be on your back for a few days or weeks, and then you can return to your normal routine. But certain flu symptoms, such as sudden dizziness or breathing problems, may signal a more serious medical problem, like sepsis or pneumonia. The flu also shares many symptoms with COVID, which can make it difficult to distinguish between the two.

Severe flu or COVID infections can lead to complications—even death. Knowing how to recognize warning signs of more serious infections can help save lives.

Typical flu symptoms

There are some telltale signs of the flu that most (but not all) people can expect to experience, including:

  • Fever
  • Chills
  • Fatigue (tiredness)
  • Muscle or body aches
  • Headache
  • Cough
  • Stuffy nose
  • Some people may have vomiting and diarrhea, though this is more common with certain strains of the flu and occurs more often among children than adults.

Many believe that if you don’t have a fever, you couldn’t possibly have the flu. This isn’t the case. Most people with the flu develop a high temperature but not everyone does.

Generally, flu symptoms resolve in five to seven days, even without treatment. In some cases, symptoms can linger for up to two weeks. If they persist beyond that time frame it may be due to more serious complications of the flu. Among those at higher risk for complications: pregnant people, those with weakened immune systems, young children, seniors and nursing home residents as well as people with blood disorders, neurologic conditions, diabetes, severe obesity and chronic lung, heart, kidney or liver disease.

If you’re in a high-risk group, you should call a healthcare provider (HCP) at the first sign of the flu. Even if you’re not in that category, if you’re very sick or worried about your symptoms, it’s best to visit your HCP. People with sick children ages 5 or younger should be sure to contact an HCP for advice about antiviral therapy. Antiviral drugs could ease symptoms and help people recover more quickly or avoid serious complications if they are given one to two days after symptoms appear.

Recognize more serious warning signs

It’s important to recognize more serious flu-like symptoms. These red flags may vary among people of different ages.  

Worrisome symptoms among babies include:

  • Trouble eating
  • Fever
  • Difficulty breathing
  • Crying without tears
  • Fewer wet diapers than usual

Additional red flags among children include:

  • Breathing problems
  • Ribs retracting, or pulling in with breaths
  • Bluish skin tone
  • Muscle pain or chest pain
  • Dehydration (dry mouth, no tears while crying, no urine for four hours)
  • Difficulty waking up or interacting with others
  • Increased or unusual irritability
  • Seizures
  • Worsening of chronic illnesses
  • Improvement in flu symptoms to later return with fever and cough
  • Fever above 104°F or a fever accompanied by a rash

Warning signs of more serious flu-related issues among adults include:

  • Shortness of breath
  • Abdominal discomfort, chest pain or severe muscle pain
  • Sudden dizziness
  • Severe weakness
  • Confusion
  • Extreme or persistent vomiting
  • Worsening of chronic illnesses
  • Flu-like symptoms that improve but then return with fever and worse cough
  • Being unable to urinate
  • Severe muscle pain

Anyone who develops these symptoms should call 911 or go to the emergency room. They could be a sign of a severe illness, such as pneumonia, an asthma attack, sepsis, inflammation of the heart or brain, or a severe case of COVID. If left untreated, these conditions can be life-threatening.

What to do if you get sick

Getting vaccinated against COVID, getting a seasonal flu shot, and practicing healthy habits washing your hands regularly, avoiding sick people, and eating a healthy diet—can help prevent infections and keep germs from spreading. But if you do get sick, here’s what you should do:

  • Call an HCP if you have serious symptoms, or if you have an increased risk of flu-related complications.
  • Stay home (unless you’re going to your HCP or the ER) and try to avoid contact with others.
  • Prioritize sleep and rest.
  • Stay hydrated. Check the color of your urine and how often you’re urinating—it should be clear to light yellow, and you should be urinating every three to five hours.
  • If your HCP says it is safe and appropriate for you, take ibuprofen (Advil, Motrin, etc) or acetaminophen (Tylenol) if you have muscle aches or a fever.

Article sources open article sources

Centers for Disease Control and Prevention. “Influenza (Flu): Flu Symptoms and Complications.” Aug 25, 2022.
UpToDate.com. “Patient education: Influenza symptoms and treatment (Beyond the Basics).” December 2020. Accessed January 27, 2021.
Centers for Disease Control and Prevention. “Influenza (Flu): Flu Treatment.” August 31, 2020. Accessed January 27, 2021.
Centers for Disease Control and Prevention. “Influenza (Flu): What To Do If You Get Sick.” January 25, 2021. Accessed January 27, 2021.
Centers for Disease Control and Prevention. “Influenza (Flu): Healthy Habits to Help Prevent Flu.” September 23, 2020. Accessed January 27, 2021.
Cleveland Clinic. “You Think It’s the Flu — Now What Should You Do?” October 16, 2019. Accessed January 27, 2021.
Cleveland Clinic. “Influenza (Flu): Management and Treatment.” November 25, 2019. Accessed January 27, 2021.
Mayo Clinic. “Influenza (flu): Overview.” December 19, 2020. Accessed February 5, 2021.
Centers for Disease Control and Prevention. “Influenza (Flu): What You Should Know About Flu Antiviral Drugs.” January 25, 2021. Accessed February 5, 2021.
Centers for Disease Control and Prevention. “Influenza (Flu): Protect Against Flu: Caregivers of Infants and Young Children.” September 15, 2020. Accessed February 5, 2021.
Centers for Disease Control and Prevention. “Influenza (Flu): Diagnosing Flu.” January 27, 2021. Accessed February 5, 2021.
Centers for Disease Control and Prevention. “Influenza (Flu): Who Needs a Flu Vaccine and When.” January 25, 2021. Accessed February 5, 2021.

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