What are antibiotics and how are they used?

Antibiotics are powerful drugs that are used to fight infections. Your healthcare team thinks you or your loved one might have an infection that can be treated with an antibiotic.

Not all infections are treated with antibiotics. While antibiotics may be effective against infections caused by bacteria (germs), they are not effective against viruses.

Like all drugs, antibiotics can have side effects and should be used only when necessary. Taking an antibiotic you don’t need can even be harmful. Because of this, there are important things to know about antibiotics.

How does my healthcare team know I need to take antibiotics?

The healthcare team may run tests to determine whether you need an antibiotic at all, and if so, which will work best. For example, your blood or urine may be checked for bacteria.

During treatment things may change. More tests and more information may show a different antibiotic is needed, or that this is a different type of infection. Tests may show that the antibiotic is not working. Or they may show an infection that cannot be treated with antibiotics.

What are side effects of antibiotics?

Antibiotics, like all medicines, may have side effects. Some can be serious.

Severe, possibly deadly diarrhea: Antibiotic use increases the risk of a gut infection caused by the bacteria Clostridium difficile (commonly called “C. diff”). When you take antibiotics, protective gut bacteria can be destroyed. Severe and sometimes deadly diarrhea can result from the C. difficile bacteria taking over your system. If you are taking antibiotics and develop severe diarrhea, let your healthcare team know immediately. Even if you stopped taking the antibiotic weeks ago and are no longer being treated, let your healthcare team know if you develop diarrhea.

Antibiotic resistance: The use of antibiotics may increase the risk of bacteria becoming resistant to them. Antibiotic-resistant infections can be very serious and difficult to treat.

Allergic reactions to antibiotics: It is important to tell your healthcare team if you have any known allergies or past drug reactions. Most emergency room visits due to antibiotic-related side effects are caused by allergic reactions to the drug. These may include mild rashes to serious skin blistering, swelling of the neck and throat, and difficulty breathing.

What questions should be asked about treatment with antibiotics?

It is important to understand what is happening with you or your loved one’s care. Here are a few important questions caregivers or patients should ask about antibiotic treatment:

  • What infection is this antibiotic treating? How does the healthcare team know that is the infection?
  • What side effects might occur from this antibiotic?
  • How long should these antibiotics be taken?
  • Are there special instructions on taking this antibiotic, such as which medications or supplements are safe to take with it, or if it should be taken with food?
  • What tests or monitoring will be done during treatment to show that the antibiotic is working?

Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy