Active therapy refers to the deliberate administration of a pharmacologically or biologically active intervention intended to directly inhibit, eradicate, or otherwise modify the course of an infectious agent or disease process.
In infectious diseases, this typically denotes treatment with antimicrobial agents (e.g., antibiotics, antivirals, antifungals, or antiparasitics) that have demonstrated activity against the causative pathogen (or a similar pathogen from the same family) and are given at doses and durations expected to achieve therapeutic efficacy. Data suggesting activity may include in vitro susceptibility results, in vivo efficacy results from animal models, and/or pharmacokinetics/pharmacodynamics probability of target attainment assessments.