Antibiotics are among the most frequently prescribed medications in healthcare, and the registered nurse sits at the center of their safe use. Nursing responsibilities span the entire medication process: verifying allergies before the first dose, collecting cultures before therapy begins, administering each agent by its correct route and rate, monitoring for adverse effects and organ toxicity, and supporting antibiotic stewardship so that these drugs remain effective for future patients. Antibiotic stewardship is the coordinated effort to ensure antibiotics are used only when genuinely indicated, at the right dose, route, and duration. Good stewardship optimizes patient outcomes while minimizing the development of resistant organisms, reducing avoidable adverse effects, and lowering the risk of complications such as *Clostridioides difficile* infection. Antibiotics are grouped by how they kill or inhibit bacteria, and understanding the mechanism helps predict both spectrum and side effects: - Cell wall synthesis inhibitors: penicillins, cephalosporins, carbapenems, and vancomycin disrupt the bacterial cell wall, causing lysis. - Protein synthesis inhibitors: aminoglycosides and tetracyclines act on the 30S ribosomal subunit; macrolides, clindamycin, and linezolid act on the 50S subunit. - DNA...