How to Tell a Viral Infection from a Bacterial Infection

Telling the difference between viral infections and bacterial infections is difficult even for physicians. Both have similar symptoms: fever and irritability. A misdiagnosis, however, can cause problems. The most common problem is when physicians prescribe antibiotics to patients with viral infections. Not only are they ineffective against that type of infection, their use builds resistance to the drug, so it will be ineffective against bacterial infections.

• 1

  Track your symptoms. Viral infections are caused by viruses. The most frequent is the common cold. AIDS and chickenpox are also viral diseases. Signs of upper respiratory infections include cough, runny nose, sore throat, low-grade fever and trouble sleeping. These same symptoms often are found in influenza, which may also bring on body aches and high fever. The duration of a viral infection is usually 10 to 14 days.

• 2

  Consider the duration of symptoms. Bacterial infections are caused by bacteria. Among the diseases causes by bacteria are tuberculosis, urinary tract infections and strep throat. They are often the result of a secondary infection. This occurs when a patient's initial viral infection leads to a bacterial infection. The symptoms of a viral infection tend to last longer than the 10 to 14 days of a viral infection. The fever is often higher and gets worse after a couple of days instead of improving. Examples of secondary infections include ear infections, pneumonia and sinusitis. The most serious bacterial infections are bacterial meningitis and sepsis.

• 3

  Ask your doctor to take a culture of the throat to see if bacterial infection is present. Although hardly foolproof, physicians can use predictors to determine whether a patient has a viral or bacterial infection. In certain cases, physicians use viral cultures to determine whether the patient needs antiviral medication. A complete blood count also may determine whether a bacterial infection is present. Physicians also rely on the medical history provided by the patient to determine the type of infection.