Dr. Meyerhof writes in "The Legacy of Islam" (P.132): "Muslim doctors laughed at the Crusaders' medical attendants for their clumsy and elementary efforts. The Europeans had not the advantage of the books of Avicenna, Jaber, Hassan bin Haytham, Rhazes. However, they finally had them translated into Latin. These translations exist still, without the translators' names. In the 16th century the books of Averroes (Inb Rushd) and avicenna (Ibn Sina) were put out in Latin translation in Italy and used as the basis of instruction in the Italian and French universities."
On page 116 of the same work he writes that after Rhazes' death the works of Avicenna (AD 980-1037) were taken up. His influence on thought and philosophy and general science was profound, and his medical works (based on the works of Galen which he had found in the Samarqand library in Arabic translation) had a sensational outreach.
Other scientists followed – Abu'l-Qais of Andalusia; Ibn-Zahr of Andalusia; Abbas the Irani; Ali ibn-Rezvan of Egypt; Ibn Butlan of Baghdad; Abu Mansur Muwaffaq of Herat; Ibbn Wafeed of Spain; Masooya o Baghdad; Ali-ibn-Esau of Baghdad; Ammar of Mosul; Ibn-Rushd (Averroes) of Andalusia; whose works were translated into Latin were used in European universities. Europe knew nothing of the cholera bacterium when Islam entered Spain, and the people there regarded the disease as a punishment sent from heaven to exact the penalty of the sins: but Muslim physicians had already proved that even the public plague was a contagious disease and nothing else that came from Allah.
Dr. Meyerhof writes of Avicenna's book "The Canon" that it is a masterpiece of medical science which proved its worth by being printed in a series of 16 editions in the closing years of the 15th century AD, 15 Latin and one Arabic. In the 16th century more than a score of further editions were published, because of its value as a scientific work. Its use continued throughout the 17th and 18th centuries, so that it became the most widely known of all medical treatises. It is still consulted in medical schools.
Will Durant writes that Mohammad ibn Zachariah Razi (Rhazes) was one of Islam's most progress physicians, author of 200 treatises and books well worth studying today: in particular his
1. "Smallpox and Measles" (published in Latin and other European tounges in 40 editions between 1497 and 1866), and
2. "The Great Encyclopedia" 20 volumes mostly unobtainable nowadays: five volumes were devoted to optics; translated into Latin AD 1279; printed in five editions in 1542 alone; known as the most authoritative work on the eye and its ailments and treatment for centuries; one of the nine basic works on which Paris University composed its medical course in 1394 AD.
Surgery made similar progress in the hands of Islamic practitioners, who even used anaesthetics, though theses are assumed to be of modern origin. They employed a henbane base. Among Rhazes' innovations was the use of cold water to treat persistent fever, of dry-cupping for apoplexy, of mercury ointment and animal gut for wound sutures, and many others.