Antibiotic resistance is threatening modern medicine. Overuse and misuse of antibiotics is driving resistance to such an extent that we have entered the post-antibiotic era, where some multidrug-and pandrug-resistant bacterial infections are no longer treatable. If the situation is not reversed, 10 million people will die annually of drug-resistant infections by 2050. More than just a question of mortality, such infections are causing the closure of wards, cancellation of operations, and interference with other common medical procedures that rely on antibiotics for their success. The response to this crisis requires co-ordinated international action with increased surveillance of bacterial resistance, infection prevention, and antibiotic stewardship, i.e. access to affordable, quality-assured antibiotics prescribed appropriately. This review describes antibiotic stewardship at the individual patient and programmatic level, which must be adopted by every prescriber if we are to preserve modern medicine for future generations.