Virus vs Bacteria

How do I know whether a virus or bacteria
caused my illness?

When in doubt, check with your doctor. But here are a few tips:

Adult illness caused by viruses:
Illness that causes a runny nose is almost always viral. Even a yellow or green runny nose is NORMAL with a cold. When a runny nose drips onto the back of the throat (called "post-nasal drip"), it causes a sore throat, and often a cough. Most sore throats are also viral, especially among adults. Viruses cause colds, and a normal cold lasts 10 to 14 days. Adults who are raising young children normally catch 3 to 4 colds a year! Normal cold symptoms are a clear, green or yellow runny nose, sore throat, cough and fever.

A virus causes flu. Flu tends to cause illness during the winter months, and often affects many people in the community. Flu should be suspected if a respiratory illness occurs during the flu season, typically between December and March. A mild case of flu may be just like a cold, but can also be much worse. Typical flu symptoms include muscle aches, extreme fatigue, fever, sore throat, headache, and cough. There are other viruses that circulate during flu season that can make you sick as well.

Viral illness can be miserable, just like bacterial illness. But misery caused by a virus cannot be relieved by medicine like antibiotics, which fight bacteria. Check with your doctor to see if antiviral medicine is available or symptomatic treatments might make you feel better. Taking antibiotics will not help, and is potentially harmful to you and the environment, including other people in your family.

Adult illness caused by both viruses and bacteria:
Either viruses or bacteria can cause fevers and coughs. When you get a sore throat with a fever, a test should be done to find out if you have a viral sore throat or a bacterial sore throat (strep throat). Strep throat can be diagnosed with a rapid strep test (while you wait) or a throat culture (takes 24 hours). Strep throat should be treated with antibiotics, but if strep tests are negative, antibiotics are not useful. Most sore throats are not caused by strep, but are viral.

Cough can be caused by many conditions affecting the airways, and commonly is caused by asthma, colds and bronchitis. Bronchitis means infection or irritation of the medium-sized airways. Bronchitis that affects normally healthy adults (acute bronchitis) is almost always viral. Acute bronchitis, also called a chest cold, is very common during cold and flu season. Medical studies prove that antibiotics do not shorten the course of acute bronchitis and do not prevent progression to more severe infections. Antibiotics do not improve cough caused by asthma or colds. Less commonly, cough can result from pneumonia, which is infection in the tissues of the lung. Viruses or bacteria may cause pneumonia, but since it is difficult to tell the difference, antibiotics are usually given. When pneumonia is the cause of cough, it is usually accompanied by shortness of breath and fever, in a patient who is noticeably sick. People with chronic lung problems (emphysema or chronic bronchitis) may have cough that requires a medical evaluation for proper treatment.

Sinus infections that cause facial pain, or that last more than 2 weeks may be caused by bacteria, and may require an antibiotic. But sinus congestion alone is common with viral respiratory infections and with allergies. Green or yellow nasal discharge does not indicate a bacterial sinus infection, but is normal with a cold. Using salt-water nose drops (e.g.:"Ocean"), and decongestants (e.g.: "Sudafed, Neo-synephrine") for colds, and antihistamines (e.g.: Benadryl, Claritin, Allegra) for allergies can dry up the congestion.

Ear pain in adults requires evaluation by a doctor, but is uncommon.