ABSTRACT Unwanted materials that coexist with active pharmaceutical ingredients (APIs), surface during formulation, or become apparent after the formulation and API have run out are known as pharmaceutical impurities. The therapeutic properties of generic drugs may be affected, even in minute quantities, by the creation of these chemical pollutants. The pharmaceutical business is currently facing significant issues with impurity control. Researchers from the International Conference on Harmonization (ICH) have worked to manage pollutants. This review describes various impurity types, sources, and degrading transcription factors using specific examples. Keywords: Impurities, Formulation, efficacy, degradation.