A Literature Review on the Impact of <em>Epilobium</em> <em>parviflorum</em> Schreb. (Onagraceae) on Vascular Dysfunction Based on Its Proven Therapeutic Properties and a Folk Medicine Believes

Background/Objectives: Water and alcohol extracts of Epilobium have gained attention due to the high concentration of its bioactive compounds and associated health benefits. This review aimed to evaluate the effects of Epilobium parviflorum Shreb. (Onagraceae) preparations on vasculature in the light of its medical application on human health over the last five years. Materials and Methods: A literature search of databases such as PubMed/Medline, Scopus, and Google Scholar for original articles published between March 2000 and March 2025 was undertaken. The keywords used were: “aortic rings”, “ellagitannins”, “Epilobium”, “hypotension”, “oenothein B”, “Onagraceae”, “systolic blood pressure”, “vasorelaxation”, “willow herb”. Only one study was found, and this was discussed in this review. Results: Herb of E. parviflorum Shreb. is used as a remedy in folk medicine with a variety of therapeutic properties, including its preventive effects and ability to relieve symptoms in patients with benign prostate hyperplasia, prostatitis, and cancer. Other properties include kidney and urinary tract diseases, skin infections and antibacterial properties. E. parviflorum contains bioactive compounds such as oenothein B, quercetin-3-O-glucuronide and myricetin-3-O-rhamnoside. In a low dose they contribute to the reduction of oxidative stress due to their antioxidant and immunostimulant effects, positively reducing inflammation that causes certain conditions. At higher concentrations Epilobium generates reactive oxygen species that stimulate the body’s defense mechanisms against a variety of cancers. Conclusions: Although the potential application of E. parviflorum in metabolic disorders was not extensively studied before, its antioxidant and anti-inflammatory properties are well documented, which suggests potential pathways for future research and therapeutic development of preparations to benefit vascular health.