Relevant aspects to the clinical use of Equisetum arvense L. (common horsetail; EA) were reviewed and a search was conducted in the databases PubMed, LILACS, SciELO, Virtual Health Library, Cochrane and Scopus using the keyword “Equisetum arvense” for articles published from 2013 through 2017. So, eighty-eight articles that addressed the pharmacognostic aspects and in vitro and in vivo biological activity, clinical trials with Equisetum arvense (EA) combined with other plants or alone, case reports concerning possible drug interactions and review studies were selected. The most relevant reported pharmacological effects included antioxidant, anticarcinogenic, antimicrobial, vascular and ileum smooth muscle relaxant, analgesic, anti-inflammatory, antinociceptive, cytotoxic, antidiabetic, hepatoprotective, antilithiatic, dermatologic, wound healing, antileishmanial, diuretic, immunizing, platelet aggregation inhibitory, osteoblast response-promoting, remineralizing, anxiolytic, sedative, anticonvulsant and cognitive performance-stimulating activities. Five clinical trials demonstrated the efficacy of phytotherapeutic complexes containing EA, with three for treating benign prostate hyperplasia, one for chronic musculoskeletal pain and one describing the effects of a topical preparation on brittle nail syndrome. Three clinical trials tested EA alone; one analyzed its pharmacokinetics; another addressed the wound-healing effect of 3% EA ointment and a randomized double-blind clinical trial found that the diuretic effect of EA was superior compared to the negative control and equivalent to treatment with hydrochlorothiazide (25 mg/ day) without changes in electrolyte excretion. Considering its long history of traditional use in several countries, in vivo and in vitro research and more recent clinical studies, EA meets the requisites for having well-defined medical applications with proven efficacy and acceptable safety.