Abstract Background Hospitals at home are increasingly offering outpatient parenteral antimicrobial therapy (OPAT) in an attempt to reduce costly inpatient care, but these settings favor broad-spectrum antibiotics that require less frequent dosing than penicillin. Benzyl penicillin could be delivered via continuous infusion pumps (eCIP), but studies on their safety and efficacy in OPAT are scarce, and it remains unclear how much the availability of eCIPs increases penicillin use in real-life settings. Methods We examined 462 electronic healthcare records of erysipelas patients treated between January 2018 and January 2022 in a large Finnish OPAT clinic. Average marginal effects from logistic models were estimated to assess how the introduction of eCIPs in December 2020 affected penicillin use, and to compare clinical outcomes between patients with and without eCIPs. Results Introduction of eCIPs increased the predicted probability of penicillin treatment by 36.0 percentage points (95% confidence interval 25.5-46.5). During eCIP implementation, patients who received an eCIP had 73.1 (58.0-88.2) percentage points higher probability than patients without an eCIP to receive penicillin treatment. They also had about 20 percentage points higher probability to be cured at the time of discharge and three months after it. Patient and nurse satisfaction regarding eCIPs was very high. Conclusions Benzyl penicillin eCIP treatment is effective and safe, and substantially increases the use of penicillin instead of broad-spectrum antibiotics. To reduce the risk of antimicrobial resistance, eCIPs could increasingly be promoted for use in OPAT clinics, and there should be adequate education and support in their implementation. Key messages • Continuous infusion of benzyl penicillin via elastomeric infusors substantially decreases broad-spectrum antibiotic use among erysipelas patients treated at home. • When erysipelas patients can be treated with outpatient parenteral antibiotic therapy, the use of elastomeric benzyl penicillin infusors is safe and effective and should thus be increasingly promoted.