Serotonergic psychedelics (also known as serotonergic hallucinogens) are a class of hallucinogenic drugs with a method of action strongly tied to the neurotransmitter serotonin. Serotonin (often referred to as 5-HT, short for its full chemical name 5-hydroxytryptamine) is a naturally occurring neurotransmitter which is tied to positive mood, certain involuntary muscle control, and countless other functions, many of which are not yet fully understood.