Fever, Sweating, Shivering and Thirst in Summer Heat?
Patient search terms: heatstroke / fever in hot weather / sweating profusely / chills and shivering / fidgety and thirsty / no appetite in summer / diarrhea after cold drinks
Medical names for this condition: summer-heat disease · summer-heat with dampness · heatstroke (yang summer-heat / yin summer-heat) · deficient upright qi · dampness retained internally
Opening: A June day, a fifty-year-old man, and an illness that hit like a collapsing mountain
Today’s case comes from Doctor Zhu Danxi, the great Yuan-dynasty physician, treating a summer-heat disease. The patient was a man in his fifties. It was the sixth lunar month — the season when the weather in the Jiangnan region starts to turn truly hot, roughly our July. Suddenly he collapsed into illness: his body ran a fever, sweat poured off him in streams — and yet at the same time he felt cold and shook all over, trembling so violently that he could not even eat. On top of that he was restless, irritable and desperately thirsty.
💬 Note from Doctor Luo: This illness sounds alarming, but the ancients had it figured out long ago. The moment Doctor Zhu Danxi took the pulse, he knew what he was dealing with — the pathogenic influence of summer-heat (shu). But to understand this case properly, we first need to get to know this particular evil qi, because summer-heat is genuinely different from ordinary heat.
First, meet summer-heat: the most unusual of the six excesses
Chinese medicine holds that the external world has six kinds of pathogenic qi, the liu yin, or “six excesses”: wind, cold, summer-heat, dampness, dryness, and fire. The word “yin” here means “excess”: summer being hot and winter being cold are normal changes of climate — but once the climate goes past its proper measure, it becomes a qi that injures people. And the most unusual of the six is summer-heat (shu).
💬 Note from Doctor Luo: Someone will ask: there’s already “fire,” and fire is heat — why set aside a separate category for summer-heat? Because summer-heat is heat taken to the extreme — scorching heat, heatstroke, these happen at the very hottest time of summer. And summer-heat has three distinctive traits that ordinary fire does not share.
First, summer-heat is a yang pathogen, and its nature is heat. A person struck by summer-heat tends to develop high fever, intense thirst, a desire to drink, a flushed face — a whole set of heat signs. Second, summer-heat rises and disperses; it consumes qi and damages fluids. In extreme heat people sweat in torrents, and with the sweat, the body’s fluids drain away; when sweating goes too far, qi escapes along with the sweat — Chinese medicine calls this “qi fleeing with the sweat” (qi sui han tuo). That is why people struck by summer heat so often feel collapsed, weak, and drowsy, with a restless heart and a racing pulse — in severe cases they faint, and life itself is endangered. Third, summer-heat almost always carries dampness with it. The worst days of summer are sauna days — hot and stifling, dampness in the air outside; and people love to gulp down cold water, which generates dampness inside the body as well. Internal and external dampness join forces and injure the spleen and stomach — vomiting and diarrhea, loss of appetite, a bloated belly, and whole-body heaviness all arrive together.
Who was the patient? A man in his fifties, gambling until his eyes were red
The patient was “in his fifties” — well past the prime of youth. In the case record, Doctor Zhu Danxi wrote down the cause of the illness in complete clarity: this man loved to gamble.
💬 Note from Doctor Luo: Notice how Doctor Zhu Danxi writes his cases — he loves to record the patient’s lifestyle habits. How bad was this gentleman’s gambling? When the gambling fever took him, he would not rest, just kept at it hour after hour, in a small stuffy room, hot and airless, sweat pouring down — and kept right on betting! In this way he “labored himself into deficiency” (zhi lao er xu), draining his upright qi bit by bit.
Doctor Zhu Danxi’s analysis: the man was older, his constitution naturally weaker than a young man’s. On top of that he gambled through the nights, exhausting himself until his body was frail. Then in the sixth month the summer heat struck — a great sweat, and with the sweat the qi fled with it, leaving the upright qi even more deficient. When qi is so weak that even the defensive qi (wei qi) at the body surface is insufficient, then when an external pathogen arrives, the first thing the person feels is cold and trembling — trembling so badly he could not even eat.
What did Doctor Zhu Danxi think? The most crucial move of the whole case
What did the pulse say? When Doctor Zhu Danxi took it: the pulse was empty, faint, thin, weak, and rapid — extremely weak and without force, thin yet beating fast.
💬 Note from Doctor Luo: An empty, faint, thin, weak pulse tells you the upright qi is insufficient; the rapid quality (shu) is a sign of depleted fluids and yin deficiency. Keep this pulse picture in mind — every judgment that follows flows from it.
Doctor Zhu Danxi pronounced his verdict: “This is a summer-heat disease.” But then he immediately revealed the most crucial judgment of the entire case — the main contradiction was not how fierce the summer-heat pathogen was, but that this man’s upright qi was too deficient. So how to treat it? Not by clearing heat and purging fire right away. First, strengthen the upright qi: decoct ginseng into a soup, and use the ginseng decoction to take down the powder of Si Ling San (Four-Powder Powder). After eight doses, the illness was cured.
Breaking down the prescription: why use dampness-dispelling herbs to treat summer-heat?
On the surface the formula looks odd: this is summer heat injuring the body, fluids badly depleted — so why reach for herbs that drain dampness? The Si Ling San that Doctor Zhu Danxi used was derived from Doctor Zhang Zhongjing’s Wu Ling San (Five-Powder Powder).
💬 Note from Doctor Luo: Wu Ling San is one of Doctor Zhang Zhongjing’s famous formulas: bai zhu (atractylodes), zhu ling (polyporus), fu ling (poria), and ze xie (alisma), plus gui zhi (cinnamon twig). The cinnamon twig warms yang and transforms qi — when yang qi is insufficient, water collects in the bladder, and urination is difficult, Wu Ling San opens up the water-dampness and restores normal fluid metabolism. Si Ling San is simply Wu Ling San with the cinnamon twig removed — because cinnamon twig is warming, and during the intense heat of summer it is no longer appropriate. Remove it, keep the bai zhu to strengthen the spleen, keep zhu ling, fu ling and ze xie to drain water-dampness. Then add ginseng to support the upright qi, strengthen the spleen, and drain dampness — attacking on three fronts at once.
Why does treating summer-heat make you think of water-dampness? The reasoning here, which Doctor Luo explains especially well, is this: summer-heat almost always carries dampness with it. On a hot, humid day people crave water and gulp down large amounts — but at that moment the body’s functions are running low, so the water they drink cannot be transported and transformed, cannot be put to use. It stays in the body and itself becomes a pathogen, stuck there, unable to be converted into usable fluids. The result is a paradox: on one hand, usable fluids are insufficient and the person is parched and restless; on the other hand, dampness is abundant; and on top of it all, the upright qi is too weak to transform any of it.
💬 Note from Doctor Luo: Someone will ask: in the early stage of summer-heat injury, when fluids are depleted, shouldn’t you use the San Dou Wu Mei Bai Tang Tang (Three-Bean Plum and Sugar Decoction — wu mei, smoked plum, and white sugar, the sour-sweet method that generates yin fluids) to replenish them? Correct — in the early stage you may. But not now. At this point the body is already full of water, and the main contradiction has become deficient upright qi plus dampness causing trouble. Now the approach must be to support the upright qi, drain the dampness, and let the body slowly restore itself. That is exactly the thinking behind Doctor Zhu Danxi’s ginseng with Si Ling San.
A digression: chasing cold in summer heat — the ancients had already paid the price
After the case, Doctor Luo Dalun shares a long, very practical discussion of “yin summer-heat” versus “yang summer-heat.” Later generations divided heatstroke into two types: yang summer-heat is when the weather is scorching, the body is burning hot, and fluids are badly damaged — this needs qi supplementation and yin nourishment, for example Doctor Wang Mengying’s Qing Shu Yi Qi Tang (Clear Summer-Heat and Boost Qi Decoction), which leans on shi hu (dendrobium) and xi yang shen (American ginseng) and other yin-nourishing herbs. Yin summer-heat, by contrast, is the illness people chase after by seeking cold in hot weather — hiding in cool caves, sitting in a drafty hall, or gulping iced drinks until the cold and damp injure the body, producing vomiting, diarrhea, and whole-body weakness.
💬 Note from Doctor Luo: The term “yin summer-heat” was introduced by Doctor Li Dongyuan. The ancients actually already had ice — it is said that Song-dynasty emperors ate ice and got diarrhea too. Everyone should understand: summer-heat itself is not divided into yin and yang. Summer-heat is heat; it is a yang pathogen. The so-called “yin summer-heat” is the consequence of our own greed for cold and improper handling — don’t blame that on the summer-heat pathogen itself. If it truly is yin summer-heat, then you use warming, dampness-dispelling herbs — Wu Ling San with cinnamon twig, or Huo Xiang Zheng Qi San (Agastache Powder to Rectify Qi) — pungent and warm to disperse, exactly right for the cold-dampness produced by sitting in air conditioning all summer.
A bonus lesson for modern life: be careful how you drink in summer heat
Finally, Doctor Luo Dalun brings the discussion back to today: cold drinks are everywhere now, and in the heat of summer, plenty of people drink iced things recklessly until their spleen and stomach break down — vomiting, diarrhea, and explosive watery stools are everywhere.
💬 Note from Doctor Luo: In summer heat, be careful what you drink — do not drink ice-cold liquids. What should you drink instead? Sour plum soup (suan mei tang) is excellent — it preserves the body’s fluids. And please don’t, just because it’s hot, go wild on watermelon and ice-cold drinks — it feels good in the moment, but the body definitely pays for it. In chasing a moment’s comfort we tend to overdo it and hurt ourselves — that is the lesson of this case for us today.
From this case we can see Doctor Zhu Danxi’s consistent philosophy of medicine: he treated the person, not just the disease. In one glance he saw that the root of this man’s problem was deficient upright qi, and so he sent the ginseng decoction with Si Ling San — support the upright, drain the dampness, and eight doses brought recovery. When we study Doctor Zhu Danxi, this is what we should study: his conviction that the practitioner must always focus on the patient’s own upright qi.
Compiled from Doctor Luo Dalun’s commentary on Doctor Zhu Danxi’s summer-heat cases (《格致余论》).