Flu season is here, and knowing when to get tested can make a difference in how you manage your symptoms and protect the people around you.
Influenza (the flu) is a contagious respiratory illness that can cause symptoms ranging from mild to severe. When some symptoms may feel similar to a common cold or COVID-19, the flu often comes on suddenly and can leave you feeling miserable.
So, how do you know when it’s time to get tested?
If you’re experiencing certain symptoms, especially during flu season, getting tested can help determine what’s making you sick and whether additional medical care is needed. Here are seven signs you shouldn’t ignore.
1. You Have a Sudden Fever or Chills
A fever is one of the most recognizable signs of the flu. Unlike a common cold, which often develops gradually, flu symptoms tend to come on quickly.
You may experience:
- A fever or feeling feverish
- Chills or sweating
- Feeling unusually hot or cold
- Body aches that develop around the same time
Not everyone with the flu develops a fever, so don’t rule it out just because your temperature is normal. If you develop a sudden fever, particularly alongside other flu-like symptoms, consider getting tested.
2. Your Body Aches and Muscles Hurt
Feeling sore after a workout is one thing. Feeling like your entire body hurts for no obvious reason is another.
Muscle aches and body pain are common flu symptoms. You may notice soreness in your back, arms, legs, or joints. These aches can sometimes be intense enough to make everyday activities uncomfortable.
3. You Have a Persistent or Worsening Cough
A dry or persistent cough is another common symptom of influenza.
You may also experience:
- A sore or irritated throat
- Chest discomfort when coughing
- Congestion or a runny nose
- Increased coughing over several days
Because the flu, COVID-19 and other respiratory illnesses can cause similar symptoms, testing can help identify the cause of your illness.
If your cough is accompanied by difficulty breathing, chest pain or other concerning symptoms, seek medical attention promptly.
4. You’re Experiencing Extreme Fatigue or Weakness
Feeling a little tired is normal. Flu-related fatigue can be much more intense. You may feel exhausted even after getting plenty of sleep, have difficulty completing normal daily activities, or feel unusually weak. Fatigue can last longer than some of the other flu symptoms, sometimes continuing for a week or more.
If you’re experiencing sudden, unexplained exhaustion alongside other respiratory symptoms, consider getting evaluated and tested.
5. You Have a Headache Along with Other Flu Symptoms
Headaches are another common symptom of influenza. They may develop quickly and occur alongside fever, chills, muscle aches or fatigue. Some people experience mild headaches, while others have more intense discomfort that makes it difficult to concentrate or go about their day.
A headache alone doesn’t necessarily mean you have the flue. However, when it occurs with several other flu symptoms, testing may help determine what’s causing you to feel unwell.
6. You’re Experiencing a Sore Throat or Runny Nose Along With Other Symptoms
Although sore throats and runny noses are often associated with the common cold, they can also occur with the flu.
Pay attention to whether these symptoms develop alongside:
- Fever or chills
- Muscle aches
- Headaches
- Coughing
- Significant fatigue
Having several symptoms at once, especially when they appear suddenly, may indicate influenza or another respiratory illness. Since flu and COVID-19 symptoms overlap, testing can help distinguish between the two.
7. You’ve Been Exposed to Someone With the Flu
If someone in your household, workplace, school or social circle has recently tested for influenza, you may have a higher chance of becoming infected. Flu symptoms typically begin about two days after exposure, although the incubation period can range from one to four days.
If you develop symptoms after being around someone with the flu, consider getting tested, particularly if you are at a higher risk for complications.
People at increased risk include:
- Adults age 65 and older
- Children younger than 5, especially those younger than 2
- Pregnant individuals
- People with certain chronic medical conditions
- People with weakened immune systems
If you are at higher risk, contact a health provider promptly when symptoms develop. Antiviral treatment may be most effective when started within 48 hours of symptom onset.
When is the Best Time to Get Tested for the Flu?
If you suspect you have the flu, don’t wait too long to seek medical guidance. Flu testing is generally most useful when performed early in the illness, ideally within the first three to four days after symptoms begin, when the amount of virus in respiratory samples is typically highest.
Testing may help your health provider determine whether you have influenza and guide recommendations for treatment and recovery. It’s also important to remember that a negative rapid flu test does not always rule out influenza. Your health provider can help determine whether additional testing is appropriate based on your symptoms and risk factors.
Flu vs. COVID-19 vs. Common Cold: What’s the Difference?
The flu, COVID-19 and the common cold share many symptoms, which can make it difficult to know which illness you have based on how you feel alone.
| Symptom | Flu | Common cold | COVID-19 |
| Fever | Common | Rare | Sometimes |
| Body aches | Common | Mild | Sometimes |
| Chills | Common | Uncommon | Sometimes |
| Fatigue | Common, sometimes severe | Mild | Common |
| Headache | Common | Less common | Common |
| Cough | Common | Mild to moderate | Common |
| Sore throat | Sometimes | Common | Common |
| Runny or stuffy nose | Sometimes | Common | Sometimes |
Symptoms can overlap, and this chart is not a substitute for testing or medical evaluation.
What Should You Do If You Think You Have the Flu?
If you think you may have influenza, consider the following steps:
- Get evaluated early. Contact a health provider if you develop flu-like symptoms, particularly if you are at higher risk for complications.
- Ask about flu testing. Testing can help identify influenza and guide appropriate treatment recommendations.
- Stay home when you’re sick. Avoid close contact with others to help prevent spreading the virus.
- Get plenty of rest and stay hydrated. Prescription antiviral medications can help shorten the duration of flu symptoms and reduce the risk of certain complications. They work best when started within 48 hours of symptom onset, although treatment may still be beneficial later for people at higher risk or with severe illness.
When Should You Seek Emergency Medical Care?
While many people recover from the flu at home, influenza can sometimes lead to serious complications, including pneumonia.
Seek immediate medical attention if you or someone you are caring for experiences:
In adults:
- Difficulty breathing or shortness of breath
- Persistent chest or abdominal pain or pressure
- Confusion, persistent dizziness or difficulty waking
- Seizures
- Severe muscle pain or weakness
- Not urinating
- Symptoms that improve but then return or worsen
In children:
- Fast or difficult breathing
- Bluish lips or face
- Ribs pulling inward with each breath
- Dehydration, such as no urination for eight hours
- Seizures
- Fever above 104°F
- Symptoms that improve but then return or worsen
For severe breathing difficulties, chest pain, or other life-threatening symptoms, call 911 or go to the nearest emergency department.
What to know about the 2026-2027 flu season
According to the CDC’s October 30, 2026 surveillance report, flu activity remains relatively low nationally but is increasing in many areas and is higher than typically observed at this point in the season. The CDC recommends annual flu vaccination for everyone six months and older.
If you or a loved one has symptoms of influenza, don’t wait for treatment—find an urgent care location near you.
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