Adulteration in Herbal Medicines: A Comprehensive Review on Types, Detection, and Health Impacts

Background: Adulteration of herbal medicines is a large-scale issue that compromises the quality, safety, and therapeutic effect of herbal drugs. It entails deliberate substitution, contamination, and incorporation of undeclared synthetic compounds, which often leads to serious adverse health effects. Objectives: This review critically examines the prevalence, character, and public health impact of herbal adulteration. It also specifies present advancements in identification methods and persistent gaps in methods and authentication. Materials and Methods: A critical literature review of world case studies, pharmacopoeial reports were taken. Emphasis was placed on the prevalence of adulteration of widely used herbal medicines. Both traditional methods of analysis (chromatographic and spectroscopic) and the newer tools, like artificial intelligence-based systems for authentication and classification, were considered. Results: Substitution adulteration is the most common, up to 70-90% in prevalent herbs like Coscinium fenestratum, Embelia ribes, and Saraca asoca. Various commercial preparations were detected to contain undeclared synthetic adulterants like corticosteroids, NSAIDs, and sildenafil. Heavy metals, microplastics, and pesticides as impurities add a triple burden of exposure, resulting in oxidative stress, endocrine disruptions, neurotoxicity, reproductive toxicity, and microbiome disruption. Though non-destructive, quick authentication techniques, most notably AI-powered image recognition and spectral analysis, are on the horizon, their application in daily quality control is still limited. Conclusion: Harmonized international regulation, more robust quality control measures, and better pharmacovigilance systems are needed urgently. Integrating interdisciplinary collaboration, building capacity, and enhancing consumer education will be key to controlling adulteration and the long-term credibility and safety of herbal medicines.