Exploring Over-the-Counter Herbal and Nutritional Products for Adult Depression: A Comprehensive Evidence Landscape

Depression is a pervasive psychiatric disorder characterized by prolonged depressed mood, anhedonia, and associated cognitive and somatic symptoms. Globally, major depressive disorder (MDD) affects up to 21% of populations, with significant functional impairment and healthcare costs. Conventional treatment includes psychological therapies and pharmacotherapies—primarily antidepressants. However, challenges such as treatment accessibility, side effects, and patient preference have led many individuals to self-manage depressive symptoms using over-the-counter (OTC) herbal medical products (HMPs) and dietary supplements. Despite widespread use, a comprehensive understanding of the research landscape surrounding these OTC products for adult depression is lacking. Addressing this gap enables clinicians and researchers to identify promising interventions, optimize clinical recommendations, and direct future research efforts efficiently.

Study Design and Methodology

A rigorous scoping review followed the Joanna Briggs Institute and PRISMA-ScR guidelines, surveying records from MEDLINE, Embase, PsycINFO, AMED, and CENTRAL databases from inception through December 2022. Inclusion criteria centred on randomized controlled trials (RCTs) evaluating single-ingredient OTC products, including HMPs, dietary supplements, and single chemical medicines, administered orally to adults aged 18-60 years with depressive symptoms or diagnoses. Studies involving comorbid conditions were eligible; however, those focusing on other primary psychiatric disorders were excluded. Outcomes included validated depression rating scales or remission. Both monotherapy and adjunctive interventions were considered. Data extraction encompassed trial characteristics, interventions, comparators, outcomes, and safety reporting. Effectiveness outcomes were synthesized via vote counting due to the heterogeneity in products and trials.