In the ancient teachings of Ayurveda, the nature and progression of fever are described with great detail. Fever, it is said, may arise from disturbances in the bodily humors—bile and wind in the head, phlegm and bile in the trika region, and wind and phlegm in the back. Such fevers tend to manifest after a day’s passage. There are further types of fever, some rooted in the impurities, fat, marrow, or bone, while others dwell solely in the marrow and bone, revealing their effects there. Phlegm, too, is recognized in two forms: one in the calves, emerging first from wind in the head; and when it reaches the bone and marrow, it behaves contrary to the fourth type previously mentioned. A threefold fever, caused by the strength of the doshas and the origin of other actions, persists for three days but releases its grip for one day. When fevers lack reversal, they may fast for seven nights, impacting not only the body but also the mind and actions, both at the time and thereafter. The fourth type of fever, arising from deep-seated behavior within the tissues and the equal increase of the doshas, is particularly difficult to treat. Subtle fevers, moving along the pathways of blood and other channels, progress slowly and lightly over a long period, inching their way through the body and leaving nothing untouched, causing burning and other discomforts. If the sequence is interrupted by effort, fever accompanied by burning is observed. Such fevers are uneven and difficult in their onset, often following the course of the night. Each stage is slower and weaker, consistent with their nature. Over time, they acquire tastes and qualities corresponding to their causes; when provoked, the disorder may burn fiercely, sometimes after a long delay. Just as a seed placed in earth and moistened with water does not wait for time to sprout, so too the seed of disorder acts without delay. And as poison, once it gains momentum, exerts its force upon the body, so does disorder and poison, agitated by the passage of time. Thus, fevers arise—irregular and persistent—bringing agitation, heaviness, dejection, collapse of limbs, and stretching. Loss of appetite, vomiting, and breathlessness are common to every type of fever, along with spitting blood, thirst, dryness, heat, and painful effort. Burning, redness, confusion, delirium, and babbling occur when blood is involved; thirst, fatigue, altered complexion, internal burning, dizziness, and darkness also afflict the patient. When the disorder resides in the flesh or fat, it brings foul smells, twitching of limbs, sweating, excessive thirst, vomiting, and sometimes a foul odor or endurance. Delirium, fatigue, loss of appetite, pain in the bones and their splitting, activation of disorder, awakening, breathlessness, spasms, and groaning are seen. In the marrow, internal burning, external coldness, breathlessness, hiccups, darkness of vision, cutting pain in vital spots, and stiffness of the genitals may occur. If the disorder reaches the semen, death may arise for those whose semen is affected. The five types that follow are increasingly difficult to cure in reverse order. Heaviness from phlegm feels as if smeared over the limbs; in mild fever, delirium appears with coldness and a covering sensation. Mild fever is always dry and passes with difficulty in cold, making the limbs stiff and weak, dominated by phlegm. In diabetes, a fever with a turmeric-like color and coating is called ‘haridraka,’ a fatal type. When phlegm and wind are both present and bile is deficient, the fever is sharp by day or mild, but arises at night. When the body’s strength is given to the sun and exhausted by exertion, fever from wind arises in the early part of the night. When the self is in the stomach and phlegm and bile are situated below, half the body becomes cold and the other half hot. When bile is placed in the body and phlegm settles at the extremities, the body becomes hot, while the hands and feet remain cold. When affliction occurs in the fluids, blood, flesh, and fat, or in the bone and marrow, the body loses its luster. The patient may become unconscious, distressed by the urge to evacuate, and look around as if angry, constantly passing foul, hot stool with force. However, when the body is light, free from fatigue, delusion, and heat; when digestion occurs in the mouth, the senses function well, there is no pain; sweating, sneezing, the mind united with its nature, desire for food, and itching on the head—all these are signs of the absence of fever. Then, the sage Dhanvantari speaks: “Now I will explain the causes of blood-bile disorder. By consuming excessively hot, bitter, pungent, sour, salty, and burning substances, or by eating kodrava, uddālaka, and similar foods repeatedly, and by excessive use of bile-provoking substances, bile becomes aggravated, turns fluid, and disturbs the blood.” When bile and blood combine and attain similarity in form, they spread throughout the body; their mixture gives rise to disorders, even from a bite. When blood displays the same smell and color as bile, it is identified as such, arising from the sites of blood, the spleen, and the liver. Symptoms include heaviness of the head, loss of taste, desire for cold, smoky or sour eructation, vomiting, aversion to food, cough, shortness of breath, dizziness, and fatigue. The blood is unhealthy, the mouth smells like fish, and in the absence of fever, there is redness, yellowish or greenish color in the eyes and other organs. The patient loses the ability to distinguish between blue, red, and yellow colors; in dreams, madness and unrighteousness manifest. When aggravated, the disorder emerges upwards from the nose, eyes, ears, and mouth; downwards from the genitals and anus; and also from the hair follicles—all these are its outlets. When associated with phlegm, it is curable by purgation; many medicines are prescribed for bile, but purgation is the best remedy. Where phlegm is also present, purification is beneficial; astringent and sweet tastes are suitable for cleansing phlegmatic disorders. Substances that are naturally pungent, bitter, or astringent, and remove phlegm, are suitable for downward-moving and chronic cases, and are treated by emesis. Thus, the wise physician learns to recognize the nature of fever and blood-bile disorders, their causes, symptoms, and the appropriate remedies, as taught by Dhanvantari.