Cyclooxygenase-1 (COX-1) is an enzyme that plays a crucial role in the production of prostaglandins, which are compounds that help regulate various physiological functions in the body. COX-1 is primarily involved in maintaining the protective lining of the stomach, supporting platelet function, and promoting kidney function. It is expressed in many tissues, including the stomach, kidneys, and platelets. COX-1 is one of two main types of cyclooxygenase enzymes, the other being cyclooxygenase-2 (COX-2). While COX-1 is generally considered to be constitutive, meaning it is always present in tissues, COX-2 is often induced during inflammation. This distinction is important for understanding the effects of nonsteroidal anti-inflammatory drugs (NSAIDs), which can inhibit both COX-1 and COX-2, leading to potential side effects.