Dealing with flu symptoms but a negative test? Learn why a flu test may be negative even with symptoms and what to do next to help your child feel better.

Published: September 17, 2025

Estimated reading time: 5 minutes

Your child has flu symptoms: a dry cough, runny nose and a sore throat. The pediatrician does a flu test, but it’s negative. What do you do when someone has flu symptoms but a negative flu test?

“It’s hard watching our kids not feel good,” said Patrick K. Hynes, M.D., pediatrician with Norton Children’s Medical Group. “We did a flu test, and it came back negative, but the child still has symptoms so how do we move forward?”

The flu has many symptoms including: 

• Cough
• Decreased appetite
• Fatigue/tiredness
• Fever
• Headache
• Muscle and body aches
• Runny or stuffy nose
• Sore throat
• Vomiting or diarrhea 

Many illnesses have similar symptoms, such as the common cold, mononucleosis (commonly called “mono”) and viral pneumonia. Illnesses such as these also give people different symptoms — some may be mild, or there may be only a few symptoms. Flu tests can give false results — false positive or negative — especially if the sample isn’t collected properly or the test is done either too early or too late in your illness.

Your pediatrician uses many tools to determine whether your child has influenza (flu). They look at how severe symptoms are, time of symptom onset and other factors. It is important to get the pediatrician’s experienced evaluation of a flu patient.

 Understanding flu tests: What parents need to know

There are two types of tests your pediatrician may use to diagnose flu or flu-like illness. Both involve taking a swab of your child’s nose to collect some of the fluid that has the flu virus in it. 

• Rapid influenza diagnostic tests (RIDTs) look for a specific protein (called an antigen) in the fluid collected from the nose.

• PCR (polymerase chain reaction) tests are more accurate than the rapid antigen test. A PCR test is a common type of molecular test. Molecular tests can be rapid (results in less than 30 minutes) or sent to a lab (results may take several days).

Timing matters when it comes to diagnosing the flu. Flu can be detected up to 24 hours before the onset of symptoms. It’s best to get tested for influenza as soon as symptoms develop, preferably within the first few days of when symptom start.

“We recommend you still get tested if you’ve had symptoms for several days, especially if your child is at high risk for complications or if they have been or may be exposed to a flu outbreak,” Dr. Hynes said. 

Why flu tests aren’t perfect

Flu tests are just one tool your pediatrician uses to determine if your child has the flu.

“Most flu tests are very accurate, especially if they are done properly, but they aren’t perfect,” Dr. Hynes said. “Laboratory swabs are the most accurate kind of flu test. A rapid antigen flu test is the least accurate type of test. Molecular tests, like a PCR test, tend to be more accurate.”

Your pediatrician looks at other factors when considering a flu diagnosis, including:

• What symptoms your child has and how severe symptoms are
• A physical examination that includes checking for fever, increased heart rate, and lung sounds
• Ruling out other respiratory illness, such as COVID-19, respiratory syncytial virus (RSV) or mononucleosis
• Medical history, including possible exposure to viruses, and preexisting conditions 
• Flu outbreaks in the community
• When and how fast symptoms developed

It is important to trust your doctor’s experience and expertise.

“All these go into consideration when we diagnose flu,” Dr. Hynes said. “It’s not just whether you have a positive or negative result from a test.”

Other viruses dan cause flu-like symptoms 

Sometimes you may hear the term “flu-like symptoms.” That refers to symptoms of illnesses that may feel like influenza, but are something else such as:

A viral infection

• Common cold
• COVID-19
• Hand, foot and mouth disease
• Mononucleosis (mono)
• RSV
• Viral meningitis
• Viral pneumonia.

A bacterial infection

• Bacterial meningitis
• Bacterial pneumonia
• Bacterial sinus infection (sinusitis)
• Strep throat
• Urinary tract infection

What caregivers can do after a child’s negative flu test 

The most important thing to do is treat your child’s flu symptoms and ask your pediatrician any questions you have. If any medication is prescribed, be sure to have your child take it as the doctor recommends. Read labels of any over-the-counter medications to be sure you are giving the correct dose for your child’s age and weight.

Immediate care may include:

• Manage pain, fever or discomfort with acetaminophen (Tylenol), children’s ibuprofen (Motrin or Advil), or the store brands of these medicines. Do not give aspirin or medications with aspirin in them to a child with the flu. 
• Encourage rest.
• Hydrate with plenty of fluids.
• A cool-mist vaporizer may relieve some congestion.
• Warm liquids such as soups or broth also can relieve some symptoms of the flu.

Continue monitoring your child’s condition 

Flu symptoms appear suddenly a few days after infection and peak in about four days. Most kids feel better in about five days. A cough may linger after other symptoms have gone away. 

Next steps after a flu test

Any symptoms — whether or not they are caused by the flu — need care. Your pediatrician is a great resource for any questions, no matter what.

“We would rather hear from you with something that turns out to be nothing, than to not hear from you at all,” Dr. Hynes said.