There are issues with broad spectrum antibiotics for sure, but they're good drugs. I can try to reassure you till I'm blue in the face , but you'll ultimately have to make the decision to take them. Your doctor prescribed these because it was determined that the benefit outweighed the risk which is an easy determination to make considering the relatively mild side effect profile of antibiotics and it's efficacy in eliminating potentially life threatening bacteria. You're comparing a certainty (the bacteria) versus an unlikely (dangerous side effects). In my mind, it's a no-brainier.