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Should I Take an Antibiotic for My Respiratory Infection?

Bacterial Infections Require Antibiotics, Viral Illnesses Do Not

By Rosalyn Carson-DeWitt, MD

Updated January 30, 2009

(LifeWire) - You've been sick for a few days now and think you might have a respiratory infection. Your throat is scratchy and sore. You're sniffling and sneezing, and your eyes are teary. You feel achy and draggy and miserable. Should you go to the doctor and request an antibiotic?

Chances are, the answer is no.

What Are Antibiotics?

Antibiotics can kill bacteria or slow their ability to multiply. The first antibiotics discovered were natural products of molds and other organisms. Infections that once killed could finally be cured and came to be considered minor and treatable. Newer, laboratory-synthesized drugs have joined the ranks of antibiotics effective against a wide variety of bacteria.

What Are Bacteria?

Bacteria are microscopic organisms found throughout nature. They can live inside or outside the human body; some are even beneficial and necessary for good health. Others, however, are "pathogenic" and they cause infection and illness. These bacteria are responsible for a whole host of human respiratory infections, including some sinus and ear infections, certain kinds of pneumonia and strep throat.

What Are Viruses?

Viruses are even tinier than bacteria. When you get a viral infection, viruses invade your body's cells, using your cells' machinery to help make more and more viruses. These viruses are responsible for the flu, the common cold and many types of sore throats, coughs, ear infections, bronchitis and even pneumonia.

Unlike bacteria, viruses are not killed by antibiotics.

Why Can't I Take an Antibiotic "Just in Case"?

There are big problems with the cavalier use of antibiotics. When bacteria are exposed to an antibiotic, while many are killed, subsequent generations of others may develop characteristics that allow them to resist being killed. While the antibiotic kills off the weakest bacteria, antibiotic resistance allows the stronger, resistant bacteria to continue multiplying. The eventual result can be "superbugs," which are very hard to kill and may only succumb to extremely powerful antibiotics. Such antibiotics pose a greater risk of significant side effects that may require hospitalization and are much more costly. Some superbugs go on to cause devastating and even fatal infections that are incurable with current antibiotics.

How Can I Tell if My Symptoms are Due to a Virus or a Bacteria?

This distinction can be tricky. That's why it's worth a visit to your doctor.

A few pointers:

  • Most virally caused colds and other upper respiratory infections will produce a wide variety of symptoms, such as a sore throat, sniffles, cough and achiness.
  • Bacterial infections often cause a more focused area of misery, such as a severely painful ear or an extremely sore throat.
  • Some of the signs (like thick, green mucus) used to be thought of or suggested the presence of a bacterial infection, but this is no longer believed to be accurate.
  • Viruses usually leave within a week. Illnesses that last more than 10 days or that grow suddenly worse after 5 to 7 days may have evolved into a bacterial infection.
  • People with underlying lung problems (such as asthma or chronic obstructive pulmonary disease) or other chronic illnesses may be more prone to bacterial infections and should seek a professional opinion sooner.

How Can I Help Prevent Superbugs?

  • Practice good hand washing to avoid becoming ill or passing an illness on to others.
  • Get a yearly flu vaccination.
  • If you become ill, talk with your doctor about whether your illness is more likely from a virus or bacteria. Don't insist on an antibiotic; ask your doctor why you do or do not need one.
  • If you do need an antibiotic, make sure you take it as directed; don't stop the medicine just because you begin to feel better. Not taking the entire prescription may allow resistant bacteria to thrive and not be completely killed off.
Remember: Don't ever take someone else's antibiotic, and don't give yours to anyone else either. Prescription medications are never meant to be shared.


"Antimicrobial (Drug) Resistance: Quick Facts." Niaid.nih.gov. Jan 2009. National Institute of Allergy and Infectious Disease, National Institutes of Health. 14 January 2009. <http://www3.niaid.nih.gov/topics/antimicrobialResistance/Understanding/quickFacts.htm>

"Bacteria Vs. Virus." Aware.md. Alliance Working for Antibiotic Resistance Education. 14 January 2009. <http://www.aware.md/PatientsAndConsumers/BacteriaVirus.aspx>

"Get Smart: Know When Antibiotics Work." Cdc.gov. Aug 2008. Centers for Disease control. 14 January 2009. <http://www.cdc.gov/drugresistance/community/index.htm>

Ong, Samuel, Janet Nakase, Gregory J. Moran, David J. Karras, Matthew J. Kuehnert, David A. Talan, and the EMERGEncy ID NET Study Group. "Antibiotic Use for Emergency Department Patients With Upper Respiratory Infections: Prescribing Practices, Patient Expectations, and Patient Satisfaction." Annals of Emergency Medicine. 50:3: (2007):213-20. <http://www.annemergmed.com/issues/contents?issue_key=S0196-0644(07)X0098-2>

Wong, David M., Dean A. Blumberg, and Lisa G. Lowe. "Guidelines for the Use of Antibiotics in Acute Upper Respiratory Tract Infections." American Family Physician. 74:6(2006): 956-66. <http://www.aafp.org/afp/20060915/956.html>

LifeWire, a part of The New York Times Company, provides original and syndicated online lifestyle content. Rosalyn Carson-DeWitt, MD, works as a medical writer, editor, and consultant in Durham, NC. She served as editor-in-chief for two multi-volume MacMillan encyclopedias: The Encyclopedia of Drugs, Alcohol, and Addictive Behavior and Drugs, Alcohol and Tobacco: Learning About Addictive Behavior. She worked on the 18th edition of the Merck Manual of Diagnosis and Therapy, and has written thousands of print and online articles for healthcare providers and consumers.

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