Abu Bakr Muhammad bin Zakaria al-Razi

(known as: Rhazes or Al Razi or Razi)

865-925 AD

Al Razi was a Persian Muslim physician, philosopher, pharmacist, and scholar who made fundamental and enduring contributions to science and medical practice. He wrote over 180 books and articles on different aspects of philosophy and medicine.

For Razi's medical practices he drew heavily upon the ancients, such as Hippocrates and Galen. However, his research as a pharmacist in the field of alchemy provided him with ways to expand upon the humor theory of his predecessors. He discovered through experimentation that objects had qualities such that of oil and sulpher, which were not readily explained by humor theory. This led him to consider a more complex elemental makeup of the world. He discovered sulfuric acid and ethanol and refined them for both medical and scientific use. Razi was also the first to describe small pox and to distinguish it from measles.

Al Razi was the medical head of the hospital in his home city of Rayy, near today's Tehran in Iran. He later headed a hospital in Baghdad, where he conducted his research and taught students. His medical textbook the al Hawi, or Comprehensive Work on Medicine was assembled by his students after his Razi's death. It was translated into Latin by Europeans in 1279 and served as a standard medical textbook in the Western world until the 1700s. It contains over 1000 of his case histories.

Among his topics in al Hawi, are comments on speech disorders. These are talked about in his chapters on the head and throat (chapters in the book are arranged according to bodily location beginning with the head and ending with the feet). Razi recognized that hoarseness of the voice was located in the larynx. The causes of hoarseness, he said were varied, including moisture, catarrh, ulceration of the lung, and inhalation of cold air (Rockey & Johnstone, 1979, p. 231). He attributed many speech problems to a malfunctioning of the tongue.

Razi, like his contemporaries and predecessors, explained some speech problems as movement restriction of the tongue caused by an attached frenum, or a tongue that is too wide or too small, too moist, or too flaccid or rigid. A common explanation for stuttering at the time had to do with the temperature of the tongue. A warm or hot tongue was good for freeing or loosening the tongue and improving speech. Razi draws from Massarjawaih, a Jewish physician and Razi's contemporary, to make this point:

If, or when, the condition (stuttering) becomes exaggerated, the breath is trapped and the heat then engendered serves to free the tongue, after the fashion of singers and the like, who have to perform for a long time (Razi quoted in Rockey & Johnstone, 1979, p. 237).

In the medical and surgical encyclopedia Continens, Al Razi described voice problems, including hoarseness. He ascribed the problems to laryngeal lining, recurrent nerves, laryngeal muscles the respiratory system and the brain. For therapy he recommended respiratory exercises and vocal training (e.g., singing the musical scales).

In Razi's therapies for speech disorders he often drew from the tenets of humor theory. For problems that he saw as due to excess moisture of the humors or the tongue, he administered drying agents. He recommended, for example, using sour fruit to dissolve excess phlegm or wrapping the tongue in cloth soaked in lettuce juice (Rockey & Johnstone, 1979, p. 240). For stuttering, Razi recommended breathing exercises (Rockey & Johnstone, 1979, p. 241).

The Razi Institute in Tehran and Razi University in Kermanshah were named after Al Razi, and he is recognized on Razi Day (Pharmacy Day) which is celebrated in Iran every August 27.

Writings of Al Razi translated into English

The Book for the Elite.

The Book of Experiences

The Cause of the Death of Most Animals because of Poisonous Winds

The Physicians' Experiments

The Person Who Has No Access to Physicians

The Big Pharmacology

The Small Pharmacology


The Doubt on Galen

Kidney and Bladder Stones

The Spiritual Physik of Rhazes

Diseases of children (see Radbill, 1971)

Rhazes' description of small-pox:

The eruption of the Small-Pox is preceded by a continued fever, pain in the back, itching in the nose, and terrors in sleep. These are the more peculiar symptoms of its approach, especially pain in the back, with fever; then also a pricking which the patient feels all over his body; a fullness of the face, which at times goes and comes; an inflamed color, and vehement redness in both the cheeks; a redness of both the eyes; a heaviness of the whole body; great uneasiness, the symptoms of which are stretching and yawning; a pain in the throat and chest, with a slight difficulty in breathing, and cough; a dryness of the mouth, thick spittle, and hoarseness of the voice; pain and heaviness of the head; inquietude, distress of mind, nausea, and anxiety; (with this difference, that the inquietude, nausea, and anxiety are more frequent in the Measles than in the Small-Pox; while, on the other hand, the pain in the back is more peculiar to the Small-Pox than to the Measles); heat of the whole body, an inflamed color, and shining redness, and especially an intense redness of the gums.

Writings about Al Razi

Iskandar, A. (1975). The medical bibliography of al Razi. In G. F. Hourani (Ed.), Essays on Islamic philosophy and science. Albany: State University of New York Press.

Radbill, S. X. (1971). The first treatise on pediatrics. American Journal of Diseases of Children, 122, 369-376.

Rockey, D. & Johnstone, P. (1979). Medieval Arabic views of speech disorders: Al-Razi (c. 865-925). Journal of Communication Disorders, 12, 229-243.