Tetrazolium Red is widely used in biological and biochemical research as a vital stain to assess cell viability and metabolic activity. It is particularly valuable in assays that measure the activity of dehydrogenases in living cells. When Tetrazolium Red is reduced by these enzymes, it forms a colored formazan product, which can be quantified spectrophotometrically to determine the number of viable cells or the level of metabolic activity.

In microbiology, it is employed to evaluate the growth and viability of microorganisms, including bacteria and fungi. In plant biology, Tetrazolium Red is used to test seed viability by staining living tissues, helping to determine the germination potential of seeds. Additionally, it is applied in toxicology studies to assess the effects of chemicals or drugs on cell survival and proliferation. Its ability to provide a clear, measurable indicator of cellular activity makes it a crucial tool in various scientific fields.