Muhammad ibn Zakariya al-Razi was born in Rayy (modern-day Iran), a city renowned as a center of learning and culture. While the exact date of his birth remains uncertain, it is estimated to be around 865 CE. Little is known about his early childhood. He was born into a well-respected family that fostered his intellectual curiosity. The culturally vibrant atmosphere of Rayy greatly influenced his future pursuits and the development of his polymathic interests.

Before dedicating himself to medicine, al-Razi explored various fields. He was reportedly a skilled lute player and singer, indicating an appreciation for the arts. He also delved into philosophy, engaging with various schools of thought. Furthermore, he spent a considerable amount of time pursuing alchemy, driven by the ambition to transmute base metals into gold. This period of diverse interests likely honed his observation skills and analytical abilities, which proved invaluable in his later medical career.

Around the age of 30, al-Razi shifted his focus to medicine. The precise reason for this transition is unclear, but it marked a significant turning point in his life. He began his formal medical studies in Baghdad, then the intellectual hub of the Islamic world, likely under the tutelage of prominent physicians of the time. This commitment to medical knowledge demonstrates al-Razi's evolving intellectual priorities and his eventual dedication to the field of medicine.

Al-Razi's exceptional abilities were quickly recognized, leading to his appointment as the chief physician of the hospital in Rayy, his hometown. Later, he also assumed the same prestigious position at the renowned Baghdad hospital. These appointments underscore his growing reputation as a skilled and knowledgeable physician, entrusted with the responsibility of overseeing medical care in major urban centers. He likely gained extensive clinical experience during this period, observing a wide range of diseases and treatments.

Al-Razi began compiling "Kitab al-Hawi" (The Comprehensive Book), one of the most extensive medical encyclopedias ever written. This massive work contained his own observations, insights, and summaries of Greek, Indian, and other medical writings. "Al-Hawi" was not organized systematically but rather served as a vast repository of medical knowledge, emphasizing clinical case studies and practical experience. This magnum opus, published posthumously, profoundly influenced medical practice for centuries.

Al-Razi wrote "Kitab fi al-jadari wa al-hasbah" (The Book on Smallpox and Measles), a groundbreaking treatise that provided the first clear and accurate descriptions of these two distinct diseases. He meticulously detailed their symptoms, stages of development, and potential complications, enabling physicians to differentiate between them for the first time. This work is considered a landmark achievement in the history of medicine and established al-Razi's reputation as a keen observer and diagnostician.

In his later years, al-Razi suffered from failing eyesight, eventually leading to complete blindness. Accounts suggest that this was caused either by cataracts or excessive exposure to fumes during his alchemical experiments. Despite his physical limitations, he continued to dictate his thoughts and writings. He died in Rayy around 925 or 935 CE. The exact circumstances of his death are not definitively known.

Abu Bakr al-Razi's contributions to medicine and science were immense and long-lasting. His works were translated into Latin and other languages, becoming standard textbooks in European medical schools for centuries. His emphasis on clinical observation, experimentation, and rational inquiry laid the foundation for modern medical practice. Al-Razi's legacy as one of the greatest physicians in history continues to inspire medical professionals and scientists today.