Adulteration in food has a detrimental effect on the product’s quality, which may result in nutritional deficiency. It can also be harmful, particularly for medicinal herbal products, as certain adulterants are very toxic to the body. It is thus critical to screen and identify the presence of any probable adulterants in food and herbal products in order to ensure the customers’ safety. Infrared Spectroscopy is a very viable technique for such purposes, as specific molecules absorb light at specific wavelengths, which correspond to the vibration frequency of the molecule’s bonds. Adulterants typically have their own unique molecular fingerprints, which exhibit their own vibrational spectra. On the basis of these principles, IR Spectroscopy is sensitive enough to detect the presence of potentially detrimental as well as harmful compounds added to food and medicinal products. This chapter describes how Infrared Spectroscopy can be beneficially used in detecting the presence of adulterants that are unintentionally or irresponsibly added to food or traditional herbal products. The last one is more of a result of a lack of knowledge and awareness of food adulterants and their deleterious impacts.