Virus or bacteria: How to tell the difference | Dr. Petter

It is officially the cold and flu season. Nobody likes to see a doctor when they are sick, simply to be diagnosed with a viral illness, sent home with instructions to drink more fluids and take Tylenol.

This scenario is common and often frustrating for consumers. Leaving a doctor’s office “empty handed,” without a prescription for an antibiotic, may seem like you have wasted your time. Some people may feel the simplicity of advice was not worth the co-pay, and certainly not the future bill to follow.

Knowing the difference between a viral and bacterial illness may save you time and money. Here are four tips to help you determine when an illness could be viral or bacterial, and perhaps when to see a doctor.

Location. A viral illness typically causes wide-spread symptoms. A bacteria usually causes site-specific symptoms, such as those involving the sinuses, throat, or chest.

Phlegm color. A virus may produce clear or cloudy mucous, if any. A bacterial illness typically causes colored phlegm (green, yellow, bloody or brown-tinged).

Duration of illness. Most viral illnesses last 2 to 10 days. A bacterial illness commonly will last longer than 10 days.

Fever. A viral infection may or may not cause a fever. A bacterial illness notoriously causes a fever (normal body temperature is 98.6, a fever is considered greater than 100 degrees Fahrenheit).

Never expect a doctor to phone-in a prescription for an antibiotic without seeing you first. Why? To ensure your illness is in fact a bacterial infection, as viruses do not respond to antibiotics. In addition, the specific location of the infection helps determine the appropriate selection and type of antibiotic prescribed.

If you are diagnosed with a bacterial illness, typical antibiotic treatment is 10 to 14 days. Once you start the antibiotic, you should begin to feel better in about 24 to 48 hours. Be sure to take the antibiotic as prescribed by your doctor, and to completion, to ensure appropriate recovery.

If you take birth control pills, be sure to use an additional form of contraception, as birth control pills may not be as effective when you are taking an antibiotic.

A person is no longer considered contagious once on an antibiotic for 24 hours and any fever has been resolved for 24 hours. Doctors assume you are cured if they do not hear back from you after the treatment course is completed. If your symptoms do not resolve, or if at any time you develop a severe headache or neck pain, persistent nausea / vomiting or a fever, be sure to see a doctor promptly.

Dr. Linda Petter, of Auburn, is a weekly feature on the ABC affiliate KOMO TV/News Radio in Seattle (1000 AM & 97.7 FM) every Sunday live 7:45 a.m., and a weekly columnist for the Auburn Reporter newspaper. She trained at the Mayo Clinic and the University of Illinois, Carle Hospital. Dr. Petter is Chief of the Department of Family Practice at St. Francis Hospital in Federal Way, WA. Her second book, Healthcare On a budget, is available on

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