Phenethylamine (PEA) is a naturally occurring monoamine alkaloid and trace amine found in the human body and in various foods, particularly chocolate. It acts as a central nervous system stimulant in humans. PEA is sometimes marketed as a dietary supplement for improving mood, based on its role as a neuromodulator and neurotransmitter. PEA can enhance the activity of neurotransmitters such as dopamine and norepinephrine, which are involved in regulating mood and emotional responses.

Scientific studies have shown that PEA levels may be lower in individuals with certain mood disorders, including depression. Some small clinical studies and case reports suggest that supplementation with PEA, especially in combination with monoamine oxidase B inhibitors (which prevent its rapid breakdown), may produce antidepressant effects and improve mood. However, these effects are typically short-lived when PEA is used alone due to its rapid metabolism in the body.

Despite these findings, the overall quality and quantity of evidence supporting the use of PEA for mood swings specifically is limited. Most research focuses on depression rather than mood swings or bipolar disorder. Major medical guidelines do not currently recommend PEA as a standard treatment for mood swings. More robust, large-scale clinical trials are needed to establish efficacy and safety for this indication.