In the hot summer months, Liu Yi San is a commonly inquired remedy, known for its affordability and practicality. The formula for Liu Yi San is quite simple, consisting of talcum powder (滑石粉, huá shí fěn) and licorice (甘草, gān cǎo) in a ratio of 6:1. Once prepared as a powder, it has a large surface area for quick action and also provides protective and astringent effects. Talcum powder has a sweet and bland taste, is slightly cold in nature, heavy and smooth in texture, and can promote dampness elimination, clear heat, and descend excess. It effectively clears heat, alleviates summer heat, promotes urination, and dispels dampness while also astringing sores, facilitating the expulsion of damp-heat from the San Jiao (三焦, sān jiāo) through urination. The proportion of licorice in Liu Yi San is minimal; its primary role here is to clear heat and harmonize, balancing the properties of the other herbs. When combined with talcum powder, it can generate fluids, facilitating urination without harming the body’s fluids, while also moderating the cold nature of talcum powder.
In summer, the heat evil is quite severe. The character for heat (暑, shǔ) has a sun above and below, with the character for earth (土, tǔ) in the middle, which symbolizes the condition of heatstroke. Externally, there is a manifestation of heat, but the function of the spleen and stomach is often weak. The heat evil is classified as a Yang evil, associated with fiery energy, and it tends to affect the heart. Therefore, after exposure to heat evil, symptoms such as high fever, irritability, thirst, and flushed face often occur. The heat evil has characteristics of rising and dispersing; the rising aspect manifests as disturbance to the spirit, leading to dizziness, chest tightness, and discomfort; the dispersing aspect manifests as sweating, and excessive sweating can damage fluids and deplete energy, resulting in symptoms like thirst, yellow urine, and fatigue. Heat often combines with dampness, leading to symptoms such as fever, thirst, fatigue, and also the pathogenic characteristics of dampness, such as heaviness in the limbs, chest tightness, nausea, vomiting, and loose stools. For instance, during outdoor activities in summer, one may only feel thirsty, dizzy, and fatigued; however, if one stays in an air-conditioned room, symptoms like heaviness in the limbs, chest tightness, and nausea may arise. If one consumes cold drinks, the spleen and stomach must expend energy to neutralize the cold, and if dampness traps the spleen and stomach, it exacerbates the damp evil, making heatstroke more likely. The efficacy of Liu Yi San includes clearing summer heat and promoting dampness elimination, indicated for symptoms such as fever, fatigue, thirst, diarrhea, and scanty yellow urine due to damp-heat. It can also be used externally to treat prickly heat (痱子, fèi zǐ). How should we understand the diarrhea mentioned in the efficacy? There may be surface heat and thirst, but the middle burner is also damp, and this dampness cannot transform into fluids to alleviate the heat and thirst. This is not contradictory; for example, when swimming in the sea, one may feel thirsty even while surrounded by water. Why is that? Because seawater does not quench thirst. The dampness in the spleen and stomach is trapped in the middle burner, while the surface presents as heat, leading to either vomiting or diarrhea. Consuming cold drinks, ice beer, or ice watermelon in summer can easily lead to diarrhea, but this type of vomiting and diarrhea is a detoxification response. It should not be deliberately suppressed; instead, timely fluid replenishment can alleviate fever and thirst while preventing fluid loss from diarrhea, such as through oral rehydration salts. If one consumes cold fruits and drinks, leading to dizziness, nausea, abdominal pain, and diarrhea, one can also take Huo Xiang Zheng Qi Shui (藿香正气水, huò xiāng zhèng qì shuǐ) to relieve symptoms. Liu Yi San can also be used externally to treat prickly heat, which is caused by high-temperature and humid environments leading to blocked pores and superficial inflammation due to sweat gland rupture. Some individuals develop transparent small blisters, while others may have red patches, depending on the severity of the blockage and the depth of the affected area.
For example, white prickly heat appears as small superficial blisters the size of a pinhead, with thin walls that easily break, containing clear fluid, and generally without noticeable symptoms. Red prickly heat is more common, occurring in areas with many folds and sweating, presenting as densely arranged pinhead-sized papules, vesicles, with surrounding redness, accompanied by mild itching or burning sensations. Liu Yi San is not only effective for prickly heat but can also be used for various skin issues caused by damp-heat, such as eczema, athlete’s foot, sweat blisters, diaper rash, urethritis, and dampness-related itching in the lower body. How to use Liu Yi San? It can be taken internally or applied externally; the dosage is 6-9g per time, 1-2 times a day. For internal use, it can be taken directly with warm water or wrapped in a gauze bag and decocted. For those who can, using fresh lotus leaves for decoction yields better results. For external use, it can be sprinkled on the affected area after bathing, and the term ‘sprinkle’ is quite illustrative, similar to how women apply foundation. If children are prone to prickly heat, Liu Yi San can also be added during their bath. Precautions: Do not use on broken skin; avoid contact with eyes.
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All Western and Chinese medicines and formulas mentioned in this article should be used under the guidance of a professional.
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