Counterfeit medicines are a growing global public health concern. These medicines may contain incorrect ingredients, no active pharmaceutical ingredient, or an improper amount of drug substance. They are often manufactured and distributed without regulatory approval and are designed to imitate genuine pharmaceutical products. This review discusses the definition, classification, challenges in detection, regulatory measures, and public health impact of counterfeit medicines, with special focus on developing countries such as India. The role of international organizations including the World Health Organization (WHO) and INTERPOL, particularly during the COVID-19 pandemic, is also reviewed. Various analytical techniques such as UV–Visible spectrophotometry, GC–MS/MS, HPLC, and LC–MS/MS used for detection of counterfeit medicines are described. Strengthening regulatory frameworks, improving public awareness, and adopting modern analytical techniques are essential to ensure patient safety and medicine quality.