The following are excerpts from Rhazes, Treatise on Smallpox and Measles. The full text is available on Google Books: click here. All section headings are my own.
Causes of the disease, and demographics of patients
I say then that every man, from the time of his birth till he arrives at old age, is continually tending to dryness; and for this reason the blood of children and infants is much moister than the blood of young men, and still more so than that of old men.
For this reason the blood of infants and children may be compared to must, in which the coction leading to perfect ripeness has not yet begun, nor the movement towards fermentation taken place; the blood of young men may be compared to must, which has already fermented and made a hissing noise, and has thrown out abundant vapors and its superfluous parts, like wine which is now still and quiet and arrived at its full strength; and as to the blood of old men, it may be compared to wine which has now lost its strength and is beginning to grow vapid and sour.
Now the disease arises when the blood putrefies and ferments, so that the superfluous vapors are thrown out of it, and it is changed from the blood of infants, which is like must, into the blood of young men, which is like wine perfectly ripened: and the disease itself may be compared to the fermentation and the hissing noise which take place in must at that time. And this is the reason why children, especially males, rarely escape being seized with this disease, because it is impossible to prevent the blood’s changing from this state into its second state, just as it is impossible to prevent must (whose nature it is to make a hissing noise and to ferment,) from changing into the state which happens to it after its making a hissing noise and its fermentation.
As to young men, whereas their blood is already passed into the second state, its maturation is established, and the superfluous particles of moisture which necessarily cause putrefaction are now exhaled; hence it follows that this disease only happens to a few individuals among them, that is, to those whose vascular system abounds with too much moisture, or is corrupt in quality with a violent inflammation; or who in their childhood have had only a mild form of the disease, whereby the transition of the blood from the first into the second state has not been perfected.
And as for old-men, the disease seldom happens to them, except in pestilential, putrid, and malignant constitutions of the air, in which this disease is chiefly prevalent.
Symptoms and prognosis
The disease is of the number of acute and hot diseases.
When the pustules are white, large, distinct, few in number, and easy in coming out, and the fever is without much violence and heat, or distress and anxiety; and when the patient’s heat and distress and anxiety diminish upon the very first eruption, and entirely cease after the eruption is completed; that sort is the most curable and least dangerous.
But when the appearance of the pustules is brought about with difficulty, and the patient is not relieved upon their eruption, they are a bad sort.
There is a bad and fatal sort of the white and large pustules, namely those which become confluent and spread, so that many of them unite and occupy large spaces of the body, or become like broad circles, and in color resemble fat.
As to those white pustules which are very small, close to each other, hard, warty, and containing no fluid, they are of a bad kind, and their badness is in proportion to the degree of difficulty in their ripening. And if the patient be not relieved upon their eruption, but his condition continues unfavorable after it is finished, it is a mortal sign.
And as to those [pustules] which are of a greenish, or violet, or black color, they are all of a bad and fatal kind; and when, besides, a swooning and palpitation of the heart come on, they are worse and still more fatal. And when the fever increases after the appearance of the pustules, it is a bad sign; but if it is lessened on their appearance, that is a good sign.
Treatment for disease in early stages
The eruption of pustules [the characteristic symptom of this disease] is preceded by a continued fever, pain in the back, itching in the nose, and terrors in sleep.
When, therefore, you see these symptoms [take the following steps]:
It is necessary that blood should be taken from children, youths, and young men who have never had the disease . . . before the pustules appear in them. A vein may be opened in those who have reached the age of fourteen years; and cupping glasses must be applied to those who are younger; and their bedrooms should be kept cool.
Let their food be such as extinguishes heat; soup of yellow lentils, broth seasoned with the juice of unripe grapes, veal broth, broth made of woodcocks, hens, and pheasants, and the flesh of these birds minced and dressed with the juice of unripe grapes. Their drink should be water cooled with snow, or pure spring water cold, with which their dwellings may also be sprinkled.
In the middle of the day let the patient wash himself in cold water, and go into it, and swim about in it. he should abstain from new milk, wine, dates, honey, and in general from sweet things; and dishes made by a mixture of flesh, onions, oil, butter, and cheese; from lamb, beef, locusts, young birds, high-seasoned things, and hot seeds.
We will now mention those medicines which thicken and cool the blood, and check its putrefaction and ebullition. These are checked by all acid things, such as vinegar and citrus juice; and still more useful are those things which have an astringency joined to their acidity, such as the juice of unripe grapes, apples, quinces and pomegranates; and those things which by their nature thicken the blood, such as lentils, cabbage, coriander, lettuce, poppy, endive, and common camphor.
This may in general suffice concerning preservation from the disease before the coming on of the fever and pustules. And by this means the disease is entirely repelled from one who is in such a condition that it can be repelled: and whatever pustules do come out must needs be favorable and few in number. By this means also it is brought about that the change in the blood from the first state into the second should not be effected all at once and in a short time, with ebullition and fermentation, which are accompanied by frightful and dangerous accidents, but little and little, and in a long time, and gradually, by way of ripening, not putrefaction, and without fevers that are either frightful, malignant, and dangerous, or else hurtful and without doubt painful.
Treatment for disease in later stages
The eruption of the pustules of the disease is accelerated by well wrapping the patient up in clothes, and rubbing his body, by keeping him in a room not very cold, and by sipping cold water, a little at a time, especially when the burning heat is very great; for cold water, when it is sipped a little at a time, provokes sweat, and assists the protrusion of the superfluous humors to the surface of the body. Let the patient put on a double shirt, with the upper border closely buttoned; and underneath let there be placed two small basins of boiling water, one before and the other behind him, so that the vapor may come to the whole body except the face; and the skin may be rarefied, and disposed to receive and evaporate the superfluous humors. For when the surface of the body is in this state, the patient is suffused with sweat, which is calculated to cool him and is very beneficial. And by this management not only is the surface of the body rendered soft, but also the strength of the patient is preserved, so that in this state nothing is more beneficial.
This method is sufficient to facilitate the expulsion of the superfluous humors to the exterior, when Nature is not languid, nor the superfluous humors too thick and viscid, and difficult to be expelled. When, however, the outward fever is mild and slight, but anxiety and inquietude continue, and the expulsion of the disease is slow and difficult, and delayed beyond the fifth day, you will then have to use those medicines which promote the eruption of the pustules.
The following is an easy, gentle mode of treatment, which will not excite too much heat, and will facilitate the eruption of the pustules:
Take yellow figs, to the number of thirty,
Of raisins stoned, twenty drachms
Pour upon them three pints of water, and let them boil gently until they are nearly dissolved. Give the patient to drink half a pint of this decoction, at three several times. Then cover him up with clothes, and expose him to hot vapor, in the manner we have before mentioned.
Treatment for scars and marks caused by the disease
The marks of the disease are of two sorts; namely either in the eye, or on the rest of the body.
In the eye the part on which the disease broke out is covered with an opaque whiteness. When this happens in the eyes of children, of those, namely, who are of a moist constitution of body, and tender skin, it is the more easily deterged.
Now, the medicines which deterge the eye and take off the whiteness, are sal ammoniac, the dungs of sparrows, swallows, starlings, mice, and crocodiles, coral, hematite, verdigris, the sediment of urine, myrrh, juniper resin, the milky juice of wild lettuce, the dung of bats, and musk. It will be best to use these when the patient is just come out of the bath, or after holding his head over the steam of hot water.
As to the medicines which remove the marks of the disease from the face and the rest of the body, they are these: white litharge, dried reed roots, rotten bones, bastard sponge, coral, sarcocol, almonds, birthwort, the ben-nut, the seeds of radish, melon, and rocket, and the meal of beans, rice, lupines, and kidney beans: let the patient be anointed with these in rice water, or barley water.
The description of a liniment which removes the marks of the disease:
Take of the meal of common chick peas,
bean meal, of each three drachms,
melon seed, five drachms,
white litharge, two drachms,
reed roots dried, three drachms
Pound all of them together in barley water; then anoint the patient several times successively after he has held his head over the steam of hot water, or after coming out of the bath. Then wash him in a bath made of a decoction of melon rinds, dried violets, bran, and common chick peas pounded; rub him well, and then apply the liniment a second time.
These, therefore, are the medicines which remove the marks and scars of the disease: and in order to efface the pock-holes, and render them even with the surface of the body, let the patient endeavor to grow fat and fleshy, and use the bath frequently, and have his body well rubbed.