What is the most important advice to give a patient about completing their antibiotic prescription?

Patients must complete the full course of antibiotics even when symptoms resolve, because symptom improvement does not mean the infection is completely eliminated. Stopping antibiotics prematurely: (1) allows surviving bacteria to repopulate; (2) selects for antibiotic-resistant bacteria (those that partially survived the initial course may be more resistant); and (3) risks recurrence of the infection. This is one of the most important principles in responsible antibiotic use to combat the global problem of antimicrobial resistance.