🌿 Folk Prescriptions

Summer refers to the months of April to June in the lunar calendar, beginning from Start of Summer and ending at Start of Autumn. This period includes six solar terms: Start of Summer, Grain Full, Grain in Ear, Summer Solstice, Minor Heat, and Major Heat.
Describing the characteristics of summer in the Huangdi Neijing (The Yellow Emperor's Inner Canon), it states: "During the three months of summer, this is called flourishing beauty; 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, creating a convergence of heavenly and earthly energies. As a result, most plants bloom and bear fruit, making it a season of abundant prosperity and beauty.
In the four seasons of the year, summer is the time when yang energy is strongest. The climate is hot and life is vigorous. For humans, this is a period of heightened metabolism.
The body's yang energy disperses outward, while yin energy remains internally, causing blood and qi to circulate more vigorously and become active on the surface of the body. To adapt to the hot climate, skin pores open up to allow sweat to be released, helping regulate body temperature and adjust to the scorching heat. When discussing how to preserve health in summer, Wang Qishi stated in Li Xun Yuan Jian (The Fundamental Principles of Treating Deficiency): "Prevent summer heat, but also avoid catching cold due to cooling down excessively; 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 cold-seeking behavior that may harm internal yang energy. This aligns with the principle in the Huangdi Neijing: “Nourish yang in spring and summer,” meaning even in the hottest summer, one must still protect internal yang energy.
Heat is the dominant factor in summer, derived from intense fire energy and occurring exclusively in summer. TCM considers heat as a yang pathogen with a rising and diffusing nature, easily depleting qi and injuring body fluids. This is its pathological feature. When heat pathogens invade the body, the pores open widely and sweating increases. Excessive sweating leads to depletion of body fluids—this is the key aspect of injury to body fluids. When body fluids are depleted, symptoms such as thirst, dry lips, hard stools, yellow urine, restlessness, and mental confusion appear. If not promptly treated, excessive opening can further deteriorate, exceeding physiological compensatory limits and inevitably depleting vital energy. At this stage, symptoms like fatigue, shortness of breath, reluctance to speak, and even sudden fainting or loss of consciousness may occur, potentially leading to death. Thus, preventing summer heat should never be taken lightly.
Dampness is the primary factor in long summer. In many regions of China, especially southern areas, it is both hot and rainy. Diseases caused by dampness frequently occur during this season. Air humidity reaches its highest level during this time. Additionally, exposure to external injuries, sweat-soaked clothing, getting wet from rain or water, or living in damp environments can lead to dampness-related illnesses.
TCM holds that dampness is a yin pathogen that easily injures yang energy. Because of its heavy, sticky, and obstructive nature, it tends to block the movement of qi, resulting in chronic and difficult-to-cure diseases—this is the pathological characteristic of dampness. Moreover, dampness easily damages spleen yang because the spleen prefers dryness and dislikes dampness. Once spleen yang is suppressed by dampness, the spleen cannot function normally in transforming and transporting food essence, 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 impaired, fluid retention occurs, commonly presenting as edema with a puffy appearance under the eyes.
TCM also believes that dampness is heavy and turbid, so after external dampness invasion, common symptoms include heaviness and fatigue in the body, and a sensation of head weight as if wrapped in cloth. Due to dampness’s sticky nature, damage often lingers and is hard to resolve. If dampness invades the skin, tendons, and bones, it typically causes persistent pain and soreness localized in one area, hence known as "Zhe Bi" (fixed arthralgia). Generally speaking, dampness-related diseases have prolonged courses. For example, damp-heat febrile diseases often exhibit a stubborn, inseparable clinical pattern. Rheumatic conditions arising from combined wind and dampness invading the skin and joints often recur repeatedly. Internal dampness diseases commonly produce pathological substances that are foul-smelling and unclean, such as exudates in skin lesions or secretions in damp leukorrhea—sticky and malodorous. Therefore, people often refer to dampness as a "visible pathogen" with an impure, turbid nature.
Since dampness often arises from moisture rising from the ground, its attack on the body usually begins from the lower part. Clinical examples such as lower limb ulcers, damp foot disease, and vaginal discharge are often related to dampness.
Modern science measures dampness using humidity—the amount of moisture in the air and the degree of object dampness. Humidity is a significant factor in weather changes and directly affects the human body. Generally, the ideal humidity range for humans is 40%–60%. When temperatures exceed 25°C, the appropriate relative humidity should be around 30%. In autumn, when the weather is cool and humidity moderate, people feel energetic. However, during the dog days of summer, due to high temperature, low pressure, and high humidity, sweat does not evaporate easily, causing discomfort, fatigue, reduced appetite, and increased risk of gastroenteritis and dysentery. If humidity is too low, mucous membranes in the upper respiratory tract lose excessive moisture, weakening resistance and increasing susceptibility to colds. Furthermore, during long summer, with hot and muggy weather, continuous rain, and humid air, clothes and food are prone to dampness, mold, and hair growth, causing discomfort. Wearing damp clothes may lead to colds or trigger joint pain, while consuming moldy or spoiled food can cause gastroenteritis or even poisoning. Therefore, during long summer, one must pay special attention to preventing dampness invasion.
"Also prevent taking cold due to heat," this warns people in hot summers to protect their internal yang energy. As the Huangdi Neijing says: "Nourish yang in spring and summer." So, how should we protect yang energy in summer?
The first point is that people should not seek immediate comfort by excessively avoiding heat and seeking coolness, such as sleeping outdoors in the cold or drinking cold beverages without restraint, which can weaken the middle energizer and allow summer heat and wind-cold pathogens to invade. When cooling down, one must particularly cover the abdomen. Many rural areas favor wearing "doudu" (abdominal wraps), which is highly consistent with health preservation principles. The Yyang Shouqin Shu (Book of Elderly Care) notes: "In summer, when the sky is hot and the earth is warm, avoid cooling under eaves, passageways, gaps in walls, or broken windows, to prevent catching the 'evil wind.'" The She Sheng Xiaoxi Lun (Discourse on Preserving Life) also advises: "Do not lie under the stars and moon, especially while asleep, nor let others fan you for coolness." These are precious experiences in health preservation, fully aligned with the spirit of "nourishing yang" in summer. The reason ancient people emphasized nourishing yang in summer lies in the fact that intense summer heat externally steams the body, causing massive sweating and open pores, making the body most vulnerable to invasion by wind, cold, and damp pathogens.
The second point is to guard against "cold air illness": this refers to a condition contracted by individuals who work and live in environments with prolonged exposure to air conditioning. Mild cases present symptoms such as facial neuralgia, lower limb pain, fatigue, headache, back pain, frequent colds, and varying degrees of gastrointestinal disorders. Severe cases may develop skin diseases and cardiovascular issues, with older adults showing more pronounced symptoms.
There are two main causes of cold air illness:
The first is that repeated daily exposure to air-conditioned environments triggers multiple cold adaptation reflexes, prompting excessive secretion of adrenaline by the sympathetic nervous system, thereby adding undue burden to the heart. In traditional Chinese medicine, there has long been the concept that summer is the season for nurturing the heart, since the five zang organs correspond to the five seasons—specifically, the heart corresponds to summer. During summer, outdoor activities increase, physical activity rises, and due to longer days and shorter nights, sleep duration is generally less than in other seasons. Consequently, the body consumes more energy, circulation accelerates, and sweating increases significantly. Clearly, the heart bears a heavy load during this season. If heart care is neglected, it is easy for the heart to suffer 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 equates to harming yang energy.
The second cause is that individuals staying long-term in air-conditioned environments experience a series of physiological reactions upon re-entering hot natural environments. Besides rapid temperature rise, the skin begins to sweat. Sweat-covered skin often harbors numerous bacteria. When returning to the air-conditioned environment, the skin and blood vessels contract immediately, allowing bacteria to easily enter the body through open pores and cause infection.
Given these circumstances, one must not indulge in excessive coolness during extreme heat to prevent cold air illness. Measures include:
Keeping indoor-outdoor temperature differences within 5°C, ideally not exceeding this. Indoor temperature should not fall below 25°C.
When going to sleep, turn off the air conditioner. Avoid keeping air-conditioned rooms sealed for long periods; whenever possible, allow indoor air to circulate with outside air.
When feeling chilly indoors, stand up and move your limbs and torso appropriately to accelerate blood circulation.
Those suffering from chronic conditions such as coronary heart disease, hypertension, arteriosclerosis, especially elderly individuals, should avoid prolonged stays in air-conditioned spaces. People with joint pain should also refrain from living in such environments.
Additionally, one must guard against dampness invasion: as previously mentioned, dampness is a yin pathogen that easily harms yang energy, particularly damaging spleen yang. While summer corresponds to the heart, long summer corresponds to the spleen among the five zang organs. Therefore, dampness in long summer most easily affects the spleen’s function, impairing digestion and absorption. According to TCM nutritional theory, dietary principles in long summer should be light and non-greasy, with warm foods preferred. The renowned Yuan dynasty health expert Qiu Chuji advocated: "Warm food, not overly full, consumed in small portions throughout the day... Avoid fatty and greasy foods." That is, food 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 the habit of eating chili peppers, because spicy food promotes sweating, providing a refreshing sensation in stifling heat. Additionally, eating spicy food aids digestion, enhances appetite, increases internal heat production, thus helping prevent the common phenomena in high temperature and high humidity—such as reduced digestive fluid secretion and weakened gastrointestinal motility.
To prevent dampness invasion, one must avoid damp living environments: TCM holds that "dampness injures flesh," meaning dampness easily damages muscles, such as in common rheumatic arthritis. The Huangdi Neijing also states: "Dampness injury first affects the lower part," where "lower" refers to the lower part of the body. This implies dampness typically attacks the body starting from the lower portion, because dampness often originates from moisture rising from the ground. Hence, its impact commonly begins from the lower body, such as common foot fungus, lower limb ulcers, and female leukorrhea. Therefore, during long summer, living quarters must be well-ventilated, moisture-proof, and heat-insulated. If indoor humidity is too high and air becomes stagnant, furniture and clothing will mold and grow hair, causing damage. It can also harm the body’s yang energy. Research in some countries on childhood rheumatism shows that over 50% of affected children were due to living in damp houses.