Phenethylamines are a class of organic compounds that contain a phenethylamine structure, which consists of a phenyl ring attached to an ethylamine chain. They are naturally occurring in various plants and animals and play a role in neurotransmission in the human brain. Some well-known phenethylamines include dopamine, norepinephrine, and epinephrine, which are important for regulating mood, attention, and stress responses. In addition to their natural forms, phenethylamines can also be synthesized in laboratories and are often studied for their psychoactive properties. Some synthetic phenethylamines, such as MDMA and amphetamine, are used recreationally and can have significant effects on mood and perception. However, their use can also lead to potential health risks and legal issues.