When it comes to dealing with an illness of bacterial or viral origin, the antibiotics of doctors are totally ineffective against viruses (which are the causes of flus and the common cold). When they do what they are designed to do, that is, destroy pathogenic bacteria in our bodies, they also destroy the friendly bacteria that our bodies need to support metabolism and the immune functions of the body.
When we have recovered from an illness with the help of antibiotics, the invading organisms may have been destroyed, but our immune systems have also been depressed. This makes us more susceptible to the next invasion of a bacteria, fungus, or virus. Hence, when children start receiving antibiotics for ear infections and other ailments of childhood, they get caught in a descending spiral of ever-recurring sickness. Once they get over one illness, they are ripe for the next. When they are sick again their systems require stronger and stronger antibiotics until they eventually end up with some sort of chronic (and possibly serious) disease later in life.