General Background: When & How to take Antibiotics


When should you take antibiotics?
Antibiotics are prescribed for illnesses caused by bacteria, not by viruses. The common cold and flu are caused by viruses, not by bacteria. Antibiotics do not work against viruses. When used prudently, antibiotics are a powerful medical tool to thwart bacterial diseases. Prudent use includes taking antibiotics only for diagnosed bacterial infections and following the precise directions on the prescription. (See About bacteria and antibiotics.)

What is the proper dosage?
Prescriptions are written to cover the time needed to help your body fight all the harmful bacteria. If you stop your antibiotic early, the bacteria that have not yet been killed can restart an infection.

Leftover antibiotics are not a complete dose, and they will not work to kill all your disease causing bacteria. Taking partial doses can select for the bacteria that are resistant. Always talk to your doctor because your symptoms may not be caused by bacteria. If you do have another bacterial infection, a complete dose of the appropriate antibiotic is needed to kill all the harmful bacteria.

How safe are antibiotics?
Antibiotics are generally safe and should always be taken as prescribed by your doctor; however,

  •  Antibiotics may alter the effectiveness of other medications and cause side effects or allergic reactions.
  •  Antibiotics can kill most of the bacteria in your body that are sensitive to them, including good bacteria. By destroying the bacterial balance, it may cause stomach upsets, diarrhea, vaginal infections, or other problems.
  •  If you take antibiotics unnecessarily you may contribute to the development of antibiotic resistance. If you become sick and your bacteria are resistant to your prescribed antibiotic, your illness lasts longer and you may have to make return office and pharmacy visits to find the right drug to kill the germ. For more serious infections it is possible that you would need to be hospitalized or could even die if the infection could not be stopped. Also, while the resistant bacteria are still alive, you act as a carrier of these germs, and you could pass them to friends or family members.
How does a physician decide which antibiotic to prescribe?
Physicians examine patients and consider their symptoms in order to tell if they should prescribe an antibiotic and, if so, which one. Physicians can also take a culture to see if bacteria are causing a particular illness, such as a throat culture to determine the presence of "strep throat." For hospital infections and some community-acquired infections, the doctor will obtain an "antimicrobial susceptibility report" that indicates which families of antibiotic drugs are useful for the particular bacteria recovered from the infection. If the cause of the infection is unclear, but suspected to be due to bacteria, the doctor may prescribe a broad-spectrum antibiotic that is useful for controlling a wide variety of bacterial types. The physician may choose either a generic or trade-name  (non-generic) antibiotic depending on the individual circumstances. 

What should women know before taking antibiotics?

  • Antibiotics often lead to a vaginal yeast infection. Because antibiotics kill the normal bacteria in the vagina, yeast no longer have competition for foodand grow rapidly. Yeast cells begin attacking tissues in the vagina, usually causing one or all of the following symptoms: itching, burning, pain during sex and vaginal discharge. If you think you have a yeast infection, consult a physician.
  • Antibiotics may reduce the efficacy of birth control pills. 
  • As with other medications, some antibiotics may be transmitted to a fetus, and some may cause harm. Therefore, you should never take antibiotics without your doctor's knowledge if you are pregnant or nursing.
 
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