Eleuthero root (Eleutherococcus senticosus), also known as Siberian ginseng, has a long history of use in traditional Chinese and Russian herbal medicine. It is classified as an adaptogen—herbs believed to help the body resist stressors of all kinds, including physical, chemical, and biological stresses. The adrenal cortex plays a key role in the body’s stress response by producing corticosteroids such as cortisol.

Traditionally, eleuthero was used to increase stamina, reduce fatigue, and enhance the body's resilience to stress, which has led to its reputation as a tonic for adrenal support. The link between adaptogens and adrenal function is mostly based on the idea that supporting the body's general stress response may indirectly support healthy adrenal cortex function.

While there is some scientific research suggesting that eleuthero may help modulate the stress response and improve endurance or cognitive function under stress, high-quality human studies specifically focusing on adrenal cortex function are limited. Most available studies are small, preliminary, or focus on general stress adaptation rather than direct adrenal hormone measurements. Thus, while tradition strongly supports its use for stress and fatigue—which involves the adrenal cortex—the scientific evidence for direct adrenal support remains limited.