Abstract Importance Recent changes in guidelines for managing Clostridioides difficile infections (CDI) have placed fidaxomicin as a first-line treatment. Objective To estimate the net cost of first-line fidaxomicin compared to vancomycin in the American and Canadian healthcare systems and to estimate the price points at which fidaxomicin would become cost saving for the prevention of recurrence. Data sources and study selection We identified randomized, placebo-controlled trials directly comparing fidaxomicin with vancomycin that reported on recurrence. Medication costs were obtained from the Veterans Affairs Federal Supply Schedule (US) and the Quebec drug formulary (Canada). The average cost of a CDI recurrence was established through a systematic review for each country. Data extraction, synthesis and outcome measures For efficacy, data on CDI recurrence at day 40 were pooled using a restricted maximal likelihood random effects model. For the cost review, the mean cost across identified studies was adjusted to reflect May 2022 dollars. These were used to estimate the net cost per recurrence prevented with fidaxomicin and the price point below which fidaxomicin would be cost saving. Results The estimated mean system costs of a CDI recurrence were $15 147USD and $8806CAD, respectively. Preventing one recurrence by using first-line fidaxomicin over vancomycin would cost $38 222USD (95%CI $30 577–$57 332) and $13 760CAD (95%CI $11 008–$20 640), respectively. The probability that fidaxomicin was cost saving exceeded 95% if priced below $1140USD or $860CAD, respectively. Conclusions and Relevance An increased drug expenditure on fidaxomicin may not be offset through recurrence prevention unless the fidaxomicin price is negotiated.