Signs and symptoms of Influenza or flu are almost similar to the signs and symptoms of common colds or other respiratory infections, that is why people might not be able to tell the difference between these types of illnesses on your own. 

The good news is, physicians can formally diagnose people with flu, common colds, or respiratory diseases with tests that can confirm the presence of the Influenza pathogen. But while these tests are usually non-invasive and fast, they might not deliver an accurate result that people expect. 

In some cases, physicians might diagnose people with the flu, or recommend them to seek treatment for the infection, based on the signs and symptoms, whether someone in the household has the same signs and symptoms or not, or if Influenza cases in the area are starting to rise. 

Immediate diagnosis of this type of illness is very important since it can cause a lot of complications for infected individuals, especially older people, infants, or immuno-compromised patients. Treatments are available to help reduce the intensity and duration of the disease.


The primary difference between upper-respiratory-tract infection or common colds and Influenza is how the disease come on. While upper-respiratory-tract infection or common colds tend to start slowly and will gradually worsen after a couple of days, flu progression is rapid. It usually begins with headaches that immediately escalates to fatigue and severe body aches.

Common Influenza signs and symptoms include:





Body aches

Exhaustion and fatigue

If a person believes that they have the flu, make sure to visit the nearest health care facility or their primary care physician within 24 to 48 hours of the onset of signs and symptoms. If they need a series of flu tests, there is a big chance that it will give an accurate result if it is performed during this time frame. 

Even if they are convinced that they have the virus, they cannot diagnose themselves. Make sure to get the opinion of physicians and other medical specialists to make sure that the self-assessment is right and accurate, and they are not suffering from other conditions that might require specific treatments.

Physical examination

Healthcare facilities and medical professionals will ask you what signs and symptoms you are experiencing and how long you have been ill to know the next step in the healing process. Physicians will look in your nose, throat, and ears, as well as listen to your lungs using a stethoscope. If the flu activity in the area is pretty high, and the signs and symptoms point to Influenza, the doctor may diagnose and treat the individual based on their assessment and eliminating other causes.

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Tests and labs

There are a lot of viral or bacterial infections that can cause signs and symptoms that are similar to those of Influenza, but will not respond to antiviral medicines that are usually used to treat Influenza. Because of this, physicians may also perform in-office flu tests to know if the signs and symptoms are consistent with the Influenza virus. 

These tests are very useful when the flu activity in the area is low, but the physician still thinks that the patient still has it. Rapid tests can be performed in the office and will only take 15 to 20 minutes to get an accurate result. These tests usually involve a throat or nasal culture to know whether Influenza A or B is present. 

If you want to know the types of Influenza, click here to find out more.

Although these tests can be beneficial, some are undermined because of the high rate of people getting false-negative test results. Some of these rapid testing, like the commonly used BD Veritor System, demonstrated a 78.8% sensitivity. 

This sensitivity is the ability of the test kit to make a correct negative diagnosis. These tests are more accurate if used for infants and will become less and less reliable as the age of the patient increases. In older people or people ages 70 years old and above, the test sensitivity might get as low as 50% to 60%, eliminating the kit’s benefits. Other tests that are more accurate can identify what strain of flu the patient has or what strain is circulating in a specific area. 

However, they are usually exclusively for research purpose use, but not totally excluded. These test kits will take longer to run, but it can help medical professionals and public health officials to assess the severity of the outbreak, know the best treatment route to take, and plan for future vaccines.