Antibiotics cure disease by killing or injuring bacteria.
The first antibiotic was penicillin, discovered in 1928. Today, over 100 different antibiotics are available to doctors to cure minor discomforts as well as life-threatening infections.
Antibiotics are not effective against viral and fungal infections. This means they are no use in dealing with colds, flu, bronchitis or most coughs. This is important because if antibiotics are used incorrectly then bacteria can become resistant.
For the same reason, it is important to complete the whole course of medication, as prescribed by your doctor.
Antibiotics fed to farm animals may also be adding to the problem of bacterial resistance (http://goo.gl/jGGM61). The World Health Organisation has called the latter a serious, worldwide threat to public health. “Without urgent action we are heading for a post-antibiotic era, in which common infections and minor injuries can once again kill” (http://goo.gl/UWcujW).
Common side effects from antibiotic use include upset stomach, diarrhea, and, in women, vaginal yeast infections. More: http://goo.gl/xljQx.