Teacrine, chemically known as theacrine, is a purine alkaloid structurally similar to caffeine and is primarily found in the Camellia assamica var. kucha tea plant. Its main biological action is as an adenosine receptor antagonist and dopamine modulator, mechanisms that influence central nervous system arousal and alertness. Although Teacrine is marketed as an energy and focus enhancer, direct scientific evidence specifically linking Teacrine to significant support or modulation of the sympathetic nervous system (SNS) is limited. A few clinical studies have demonstrated that Teacrine can increase subjective feelings of energy, improve mood, and reduce fatigue without causing the habituation or cardiovascular stimulation often seen with caffeine. Some studies also report modest increases in heart rate and blood pressure, which are markers of sympathetic activation, but these findings are inconsistent and generally less pronounced than with caffeine.

Overall, the use of Teacrine for supporting the SNS is based on its stimulant-like effects and its molecular similarity to caffeine, which is a well-established SNS activator. However, the available scientific evidence is preliminary and limited in both scope and scale, with few high-quality or long-term studies directly evaluating its impact on the SNS in humans. Therefore, while there is some scientific rationale for its use, the strength of the evidence is weak, meriting a score of 2 out of 5.