Antibiotics kill germs, all germs. Very usefull with infections such as pneumonia They can save your life. However, The intestines require germs to process the food you eat and if you kill all the germs off you cannot absorb nutrition. So after any antibiotic regime put the good germs back in your colon with a good probiotic, preferably from food. I have found barefoots recomendation of eating one whole pineapple a week for 2 weeks suficient to do this. The colon needs germs to process food.