4-Iodoamphetamine hydrochloride is primarily utilized in research settings, particularly in neuroscience and pharmacology. It acts as a serotonin receptor agonist, making it valuable for studying the serotonin system in the brain. Researchers use it to investigate the effects of serotonin on behavior, mood regulation, and neurochemical pathways. Additionally, it has been employed in radiolabeling studies to trace and visualize serotonin receptors in the brain, aiding in the understanding of psychiatric disorders and the development of potential therapeutic agents. Its application is strictly confined to controlled laboratory environments due to its potent psychoactive properties.