The Centers for Disease Control and Prevention (CDC) says there are two main types of germs that cause most infections: viruses and bacteria. Antibiotics are powerful drugs used to treat certain illnesses, but they don't work against viruses such as colds and flu, but they do kill specific bacteria. The CDC cautions that antibiotics do not cure everything, and unnecessary use of antibiotics can even be detrimental. But if your illness is treatable by antibiotics, remember that there are pros and cons of using these drugs. Click on the tabs above for more information.