Epinephrine, commonly known as adrenaline, is a hormone and neurotransmitter produced by the adrenal glands. It plays a crucial role in the body's fight-or-flight response, increasing heart rate, blood pressure, and energy supply during stressful situations. In medical settings, epinephrine is used to treat severe allergic reactions, known as anaphylaxis, and to manage cardiac arrest. It can be administered through injections or auto-injectors, such as the EpiPen, to quickly counteract life-threatening symptoms.