Addiction is a complex and global problem. Its profound impacts don't include the addicts only, but also family, and whole society such as homelessness, unemployment, relational conflicts, and psychiatric comorbidity. Physical addictions can be classified into three groups: illicit (illegal) drugs, alcohol, and prescription drugs. The availability of a wide range of illicit drugs, often mixed with unknown substances, poses a significant seriousness on drug users. Many users lack awareness of both content and quality of the compounds they consume. Drug addiction can be a serious hazard, causing acute and chronic effects on health, compounded by the presence of potentially harmful drug adulterants. This review seeks to create a comprehensive overview of substances employed for adulteration or cutting agents in those illegally distributed drugs (illicit), particularly focusing on pharmaceuticals or medicines in recent years. Analysis of seized tablets purportedly containing tramadol and tapentadol has uncovered the use of venlafaxine as an adulterant their tablets. Pregabalin is frequently detected as adulterants in seized herbal samples contain synthetic cannabinoids.