Hematoporphyrin dihydrochloride is primarily used in medical research and clinical applications, particularly in the field of photodynamic therapy (PDT). It serves as a photosensitizing agent, which, when exposed to specific wavelengths of light, generates reactive oxygen species to target and destroy cancer cells. This property makes it valuable in treating certain types of cancers, such as skin, bladder, and esophageal cancers. Additionally, it is utilized in diagnostic imaging to identify malignant tissues due to its ability to accumulate selectively in tumor cells. Its role in both therapeutic and diagnostic applications highlights its importance in oncology and biomedical research.