The doctor will ask about symptoms and past health. A cold or influenza can be diagnosed based on symptoms. In some situations, tests, such as throat culture or blood count, may be done. Tests may be based on how severe the symptoms are. They may also be used to check for other problems.
It is not usually necessary to find the virus causing the symptoms. This is because it usually does not make a difference in treatment. However, if influenza A virus is suspected, treatment may be given to those at high risk for infection.
Diagnosis may include the following:
Monitoring a fever—A person's temperature may be checked every 6 to 8 hours. This can help define the severity of the illness.
Urinalysis—A routine urine check is not usually done for colds or flu. However, it may be done to check for conditions such as diabetes. Diabetes may make a cold or influenza worse. It may also be done if a urinary infection is suspected.
Blood tests—This is another routine test. It is done to assess a person's general health and ability to fight off the illness. It is not done routinely in colds or flu. It is only needed if a person is very sick.
Throat Culture—This may be done for a sore throat to rule out strep throat, a bacterial infection.
Chest X-ray —An image may be taken if the doctor thinks an infection has spread to the lungs. The xray is done to check for pneumonia.
References
Common cold. Merck Manual Professional Version website. Available at: http://www.merckmanuals.com/professional/infectious-diseases/respiratory-viruses/common-cold. Accessed March 9, 2022.
Influenza. Merck Manual Professional Version website. Available at: http://www.merckmanuals.com/professional/infectious-diseases/respiratory-viruses/influenza. Accessed March 9, 2022.
Influenza in adults. EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/influenza-in-adults. Accessed March 9, 2022.
Upper respiratory infection (URI) in adults and adolescents. EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/upper-respiratory-infection-uri-in-adults-and-adolescents-18. Accessed March 9, 2022.