Efficacy of Polypodium vulgare L. root decoction in symptom management of hospitalized patients with severe acute respiratory infection: A randomized controlled trial.

BACKGROUND: Severe acute respiratory infections remain a major cause of global morbidity and mortality, particularly in low-resource settings where supportive treatment options are limited. Identifying safe, accessible adjunctive therapies is therefore a clinical priority. This study examined whether Polypodium vulgare L. root decoction, used as an adjunct to standard care, could influence prespecified longitudinal clinical and laboratory parameters, particularly vital-sign and oxygenation trajectories, during the 14-day follow-up period in adults hospitalized with mild to moderate severe acute respiratory infection. METHODS: In this randomized, multicenter trial with blinded outcome assessment, adults were assigned to receive P. vulgare root decoction plus standard care or standard care alone. Nine clinical and laboratory parameters were monitored over 14 days, and daily changes between groups were analyzed using longitudinal generalized estimating equations. Plant material was authenticated following ConPhyMP guidelines, and a voucher specimen (TM-1179) was deposited at the Shiraz University of Medical Sciences Herbarium. RESULTS: Eighty-eight participants completed the study (44 per arm). Adjunct P. vulgare therapy produced a faster reduction in heart rate (P < 0.0001) and a greater daily improvement in oxygen saturation (P = 0.004) compared with standard care alone. Conversely, reductions in inflammatory markers-erythrocyte sedimentation rate and C-reactive protein-were slower in the P. vulgare group (P < 0.0001), and the absolute neutrophil count increased more rapidly in the experimental arm than in the control arm (P = 0.003). No serious or fatal adverse events occurred in either group. CONCLUSIONS: Use of P. vulgare root decoction alongside standard care may enhance cardiorespiratory recovery in adults with mild to moderate severe acute respiratory infection, although its effects on inflammatory biomarkers appear variable. Larger, controlled trials are needed to confirm these findings and to clarify the therapeutic value of this adjunctive approach. TRIAL REGISTRATION: Iranian Registry of Clinical Trials (IRCT20120506009651N4; registered 07 June 2022).