Lugol’s solution, acid has a similar composition as Lugol’s solution. It was named after French physician J. G. A. Lugol, and it is widely used in the field of medicine. It is most commonly known as an antiseptic, disinfectant and starch indicator. Lugol’s solution affects the carbohydrate molecules in the following way: iodine binds to complex carbohydrates (starch in plant organisms, glycogen in animals), staining them in the process. Lugol’s solution, acid is an aqueous solution of iodine and potassium iodide with added acid. It is used in cytology and parasitology for staining parasites in stool samples, in zoology for staining protozoa in order to strengthen the contrast of inner structures (nuclei and glycogen vacuoles) and for conserving the protozoa.