Cortisol, also known as hydrocortisone, Compound F, or Cortef, is an endogenous glucocorticoid hormone produced by the adrenal cortex. It belongs to the steroid hormone class and plays a crucial role in various physiological processes. Cortisol is synthesized from cholesterol and is released in response to stress and low blood-glucose concentration. Synthetic forms of cortisol are used in medicine to treat a variety of conditions. Researchers have extensively studied cortisol due to its significant impact on the body's stress response and metabolic functions. It is primarily involved in the regulation of metabolism, immune response, and maintenance of homeostasis. Cortisol's role in the body's response to stress, inflammation, and circadian rhythms has been a major focus of research. Its dysregulation is associated with conditions such as Cushing's syndrome and Addison's disease. Cortisol exerts its effects by binding to glucocorticoid receptors, which are part of the nuclear receptor superfamily. Upon binding, the hormone-receptor complex translocates to the nucleus, where it influences the transcription of target genes involved in glucose metabolism, immune response, and other vital processes. Researchers have found that cortisol's action involves complex signaling pathways that modulate various physiological responses. The pharmacokinetic properties of cortisol include a circulating half-life of approximately 70 minutes. It is metabolized primarily in the liver and excreted in urine. Oral bioavailability is limited due to first-pass metabolism. Cortisol is used clinically in its synthetic form to treat inflammatory and autoimmune conditions, among others. It is approved by regulatory agencies like the FDA for various therapeutic uses. Researchers have observed its efficacy in managing conditions such as asthma, rheumatoid arthritis, and adrenal insufficiency. Its use is regulated and requires a prescription.