🌿 Folk Prescriptions

Summer refers to the months of April to June in the lunar calendar, beginning from Start of Summer and ending on Start of Autumn. This period includes six solar terms: Start of Summer, Grain Full, Grain in Ear, Summer Solstice, Minor Heat, and Major Heat.
According to The Yellow Emperor’s Inner Canon, describing the characteristics of summer solar terms, it states: “In the three months of summer, this is called flourishing and blooming; the energies of heaven and earth converge, and all things blossom and bear fruit.” This means that during the three months of summer, the yang energy of heaven descends while the heat from the earth rises upward, causing the energies of heaven and earth to intermingle. Most plants flourish and bear fruit, making it a season of abundant beauty and vitality.
In the four seasons of the year, summer is the time when yang energy is strongest. The climate is hot and full of life force. For humans, this is a period of vigorous metabolism,
when the body's yang energy spreads outward, with yin energy remaining internally. Blood and qi circulation also become more active and are concentrated at the surface of the body. To adapt to the hot climate, skin pores open up, allowing sweat to be released. Through sweating, body temperature is regulated to suit the hot and humid weather. When discussing how to preserve health in summer, Wang Qishi stated in The Mirror of Rationality in Treating Deficiency: “Prevent summer heat, but also avoid taking cold due to heat; in long summer, prevent dampness.” This clearly outlines the fundamental principles of summer health preservation: guard against summer heat in peak summer; guard against dampness in long summer; meanwhile, protect the body’s yang energy, avoiding excessive coldness in an attempt to escape heat, which could harm internal yang energy. As The Yellow Emperor’s Inner Canon points out, “Nourish yang in spring and summer,” meaning even in the scorching summer, one must still pay attention to protecting internal yang energy.
Heat is the dominant factor in summer, derived from intense fire energy, manifesting exclusively in summer. In TCM, heat is considered a yang pathogen, characterized by rising and dispersing tendencies, easily depleting qi and injuring body fluids. This is its pathological feature. When heat pathogen invades the body, it causes the pores to open excessively and leads to profuse sweating. Excessive sweating results in reduced body fluids—this is the key to injury of body fluids. When body fluids are injured, symptoms such as intense thirst, dry lips, constipation, dark urine, irritability, and mental confusion appear. If not promptly treated, excessive opening may further develop into severe depletion of vital energy. At this stage, symptoms like fatigue, shortness of breath, lack of speech, and even sudden collapse or unconsciousness may occur, potentially leading to death. Thus, preventing summer heat should not be taken lightly.
Dampness is the primary factor in long summer. In many regions of China, especially southern areas, summers are both hot and rainy. Diseases caused by dampness are common during this season. Air humidity reaches its highest level during this time. Additionally, exposure to external injuries, sweat-soaked clothes, getting wet from rain or water, or living in damp environments can lead to infection by damp pathogens.
TCM holds that dampness is a yin pathogen, prone to damaging the body’s yang energy. Because of its heavy, sticky nature, it easily obstructs the flow of qi, resulting in chronic and difficult-to-cure diseases—this is the pathological characteristic of dampness. Moreover, dampness tends to damage spleen yang, since the spleen prefers dryness and dislikes dampness. Once spleen yang is suppressed by dampness, the spleen’s normal function of transforming and transporting food and fluids becomes impaired, leading to stagnation of qi. Clinically, this manifests as abdominal distension, poor appetite, loose stools, and cold limbs. Especially when the spleen’s ascending and descending functions are disrupted, fluid retention occurs, commonly seen as edema with a puffy appearance under the eyes.
TCM also considers dampness heavy and turbid, so external dampness often causes symptoms like heaviness, fatigue, and a sensation of head weight as if wrapped in cloth. Due to dampness’s sticky nature, damage tends to be persistent and hard to resolve. If dampness affects the skin and tendons, it often causes pain and stiffness localized in one area, hence known as “Zhuo Bi” (fixed arthralgia). Generally, dampness-related illnesses have prolonged courses. For example, damp-heat disease often presents clinical features resembling oil mixed into flour—difficult to separate. Rheumatic conditions arising from combined wind and dampness affecting skin and joints often recur repeatedly. Internal dampness frequently produces pathological secretions that are foul-smelling and unclean, such as exudates in skin lesions or vaginal discharge in damp leukorrhea, which are sticky and malodorous. Therefore, people often refer to dampness as a “visible pathogen” with a filthy nature.
Since dampness often arises from moisture rising from the ground, it typically attacks the lower parts of the body first. Clinical examples include lower limb ulcers, damp foot conditions (such as tinea pedis), and vaginal discharges—all associated with dampness.
Modern science measures humidity as the amount of water vapor in the air, indicating the degree of moisture in objects. Humidity is a significant factor in climate change and directly affects human health. Generally, the ideal humidity range for humans is 40%–60%. When temperatures exceed 25°C, the ideal relative humidity is around 30%. In autumn, cool weather and moderate humidity boost mental alertness. However, during the dog days of summer, high temperatures, low pressure, and high humidity make it difficult for sweat to evaporate after being released, causing restlessness, fatigue, loss of appetite, and increased risk of gastroenteritis and dysentery. If humidity is too low, the mucous membranes of the upper respiratory tract lose excessive moisture, weakening resistance and increasing susceptibility to colds. Furthermore, during long summer, hot and muggy weather with continuous rain makes clothing and food prone to dampness, mold, and hair growth, causing discomfort. Wearing damp clothing increases the risk of catching a cold or triggering joint pain, while consuming moldy or spoiled food can cause gastroenteritis or even poisoning. Therefore, it is essential to guard against dampness during long summer.
“Also prevent taking cold due to heat”—this warns people in hot summer to protect their internal yang energy. As The Yellow Emperor’s Inner Canon says: “Nourish yang in spring and summer.” So, how should we protect yang energy in summer?
The foremost point is that people must not seek only immediate comfort by excessively avoiding heat and seeking coolness—for instance, sleeping outdoors in the cold night or drinking cold beverages without restraint—leading to internal deficiency of middle qi, thus allowing summer heat and wind-cold pathogens to invade. When cooling down, one must particularly cover the abdomen. Many rural areas prefer wearing “doubi” (abdominal wraps), which aligns well with health preservation principles. The Book of Elderly Care states: “During summer, when the sky is hot and the earth is warm, avoid sitting in shaded passageways, through gaps in walls, or under broken windows, to prevent invasion by evil winds.” The Treatise on Preserving Life also advises: “Do not sleep under the stars, nor let yourself fall asleep while fanning, to cool off.” These are precious experiences in health preservation, consistent with the spirit of “nourishing yang” in summer. Ancient people emphasized preserving yang energy in summer because summer heat externally steams the body, causing profuse sweating and open pores, making the body most vulnerable to invasion by wind, cold, and damp pathogens.
Secondly, one must guard against cold-induced illness: Cold-induced illness refers to diseases contracted from prolonged exposure to air-conditioned environments. Mild cases may involve facial neuralgia, lower limb pain, fatigue, headaches, backaches, frequent colds, and varying degrees of gastrointestinal issues. Severe cases may lead to skin diseases and cardiovascular disorders. Symptoms are particularly pronounced among the elderly.
There are two main causes of cold-induced illness:
First, repeated entry and exit from air-conditioned environments cause the body to undergo multiple cold adaptation reflexes, stimulating excessive secretion of adrenaline by the sympathetic nervous system, thereby adding hidden burden to the heart. In TCM theory, there has long been the saying that summer is suitable for nourishing the heart, as the five zang organs correspond to the five seasons. Specifically, in summer, the heart corresponds to the season. During summer, outdoor activities increase, physical activity rises, and due to longer days and shorter nights, sleep duration decreases compared to other seasons. Consequently, the body consumes more energy, blood circulation accelerates, and sweating increases significantly. Clearly, the heart bears heavy strain during this season. If heart care is neglected, it is easy to cause heart damage. From this, it is evident that repeatedly entering and exiting air-conditioned environments is detrimental to the heart. Since the heart belongs to fire, harming the heart damages yang energy.
Second, individuals who remain long in air-conditioned environments experience a series of physiological reactions upon returning to hot natural surroundings. Besides rapid temperature rise, the skin begins to sweat. Sweat-covered skin often harbors many bacteria. When people re-enter the air-conditioned environment, the skin and blood vessels contract immediately, allowing bacteria to easily enter the body through open pores, causing infection.
Given these circumstances, one must not indulge in excessive coolness during extreme heat to prevent cold-induced illness. Measures include:
Keeping indoor-outdoor temperature differences within 5°C, ideally not exceeding this. Indoor temperature should not drop below 25°C.
Turn off air conditioners before sleeping; avoid keeping air-conditioned rooms sealed for long periods. Whenever possible, allow indoor air to circulate with outside air.
When feeling cool indoors, stand up and move arms and legs appropriately to accelerate blood circulation.
Those suffering from chronic conditions such as coronary heart disease, hypertension, or arteriosclerosis—especially the elderly—and those with joint pain should avoid staying long in air-conditioned environments.
Additionally, one must guard against dampness: As previously mentioned, dampness is a yin pathogen that easily harms yang energy, especially damaging spleen yang. In peak summer, the heart corresponds to the season, whereas in long summer, the spleen—the organ corresponding to the season—becomes most vulnerable to dampness. Thus, dampness in long summer most readily impairs spleen function, leading to diminished digestive and absorptive capacity. According to TCM nutrition, dietary principles in long summer should be light and less greasy, favoring warm foods. The renowned Yuan Dynasty health expert Qiu Chuji advocated: “Warm food, not overly full, eaten in small portions throughout the day… Avoid fatty and greasy foods.” That is, diet in long summer should be slightly warm—not excessively cold; avoid overeating, but consume meals more frequently. In some southern regions of China, many people have a habit of eating chili peppers, because spicy food promotes sweating, creating a sense of cool comfort in stifling heat. Moreover, eating spicy food aids digestion, stimulates appetite, increases internal heat production, helping prevent the common phenomena in high temperature and high humidity—reduced digestive fluid secretion and weakened gastrointestinal motility.
To prevent dampness invasion, living environments must avoid dampness: TCM holds that “dampness injures flesh,” meaning dampness easily damages muscles, such as in common rheumatoid arthritis. The Yellow Emperor’s Inner Canon also notes: “Those injured by dampness suffer first in the lower part,” where “lower part” refers to the lower body. This implies dampness typically attacks the lower body first, as dampness often originates from moisture rising from the ground. Hence, dampness commonly affects the lower body, such as tinea pedis, lower limb ulcers, and vaginal discharges in women. Therefore, during long summer, dwellings must be ventilated, moisture-proof, and heat-insulated. If indoor spaces are overly damp and air is polluted, furniture and clothing will mold and grow hair, causing damage. It also harms the body’s yang energy. Research in some countries on childhood rheumatic diseases shows that over 50% of affected children were caused by living in damp houses.