A greater than normal concentration of epinephrine in the blood.

Epinephrine is a substance produced by the medulla (inside) of the adrenal gland.

The name epinephrine was coined in 1898 by the American pharmacologist and physiologic chemist (biochemist) John Jacob Abel who isolated it from the adrenal gland which is located above (epi-) the kidney (Greek nephros).

Epinephrine causes increased rapidness of the heart beat, strengthens the force of the heart's contraction, opens up the airways (bronchioles) in the lungs, and has numerous other effects.