Agents that inhibit the activity of bacterial beta-lactamases, enzymes that hydrolyse and inactivate beta-lactam antibiotics and are a common cause of antibiotic resistance.

To protect the beta-lactam antibiotic from inactivation, beta-lactamase inhibitors are used in combination with a beta-lactam drug (BL–BLI combinations). Examples of beta-lactamase inhibitors include clavulanic acid, sulbactam, tazobactam and avibactam.