# Why Does TCM Say "Cold Is a Stagnating Evil"? Like an Ice Sculptor Freezing Your Body in Place
A Question
Have you ever experienced this?
You go out in winter without gloves, and your fingers go numb and stiff; even after coming back inside, they take half a day to warm up. You eat a big bowl of ice watermelon, and your stomach immediately cramps, sending you running to the bathroom. You drink a cold beverage during your period, and your lower abdomen throbs with pain, as if there's a block of ice inside. Your knees ache faintly in winter, getting worse when it's cold, easing with a hot compress. The doctor says: "Cold evil stagnates; where there is blockage, there is pain." You ask: "Isn't cold just low temperature? How did it become a pathogenic evil?"
You ask a Western doctor: "What is cold?" The doctor says: "There's no such concept as cold. It might be vasoconstriction or muscle spasms."
You ask a TCM practitioner: "What exactly is cold?" The old doctor says: "Cold has the nature of stagnation and causes pain. Cold causes qi to contract; blood flow is not smooth."
One says "vasoconstriction," the other says "cold stagnation"—are they talking about the same thing?
Even more surprising, TCM says cold is also divided into two types: external cold (colds, frostbite, joint pain) and internal cold (yang deficiency, cold uterus, cold limbs). External cold can be understood—it's cold, after all. But what is the "cold" inside the body? Insufficient yang qi? Cold uterus? What exactly is going on?
Traditional Chinese Explanation
The concept of "cold" (han) was systematically defined in the Huangdi Neijing. The ancients observed that some people get joint pain after being exposed to cold, some get abdominal pain after eating cold food, some have cold hands and feet in winter, and some get menstrual cramps after being exposed to cold during their period. They summarized this pathogenic characteristic of "contraction, stagnation, and pain" as cold evil—"cold has the nature of stagnation and causes pain" (Suwen·Bi Lun).
TCM summarizes the functions and characteristics of "cold" into three keywords: contract, stagnate, and pain.
Contract (shou)—"cold causes qi to contract." Cold causes pores to contract, blood vessels to constrict, and muscles to tighten. When exposed to cold, goosebumps appear on the skin (pore contraction), hands and feet become cold (vasoconstriction), and muscles become stiff (muscle contraction). This is the body's self-protection—reducing heat loss. But excessive contraction leads to poor qi and blood flow.
Stagnate (ning)—"cold has the nature of stagnation." Cold causes qi and blood to flow more slowly, like water freezing. Blood viscosity increases, blood flow slows, and metabolic products accumulate. After joints are exposed to cold, synovial fluid viscosity increases, and joint movement becomes less flexible. This is "stagnation"—not actually freezing, but a slowing and thickening of physiological activity.
Pain (tong)—"causes pain." Pain caused by cold evil is the most typical. Because qi and blood are stagnant, where there is blockage, there is pain. Vasoconstriction causes tissue ischemia, and metabolic products (lactic acid, bradykinin) accumulate, stimulating nerve endings and producing pain. A hot compress causes blood vessel dilation, improves blood flow, and relieves pain—"where there is free flow, there is no pain."
Cold is also divided into external cold and internal cold:
• External cold—exposure to cold evil from the outside, invading through the skin. Wind-cold cold (aversion to cold, no sweating, headache), frostbite (pale skin, numbness), cold bi syndrome (cold pain in joints, aggravated by cold), cold stagnation abdominal pain (abdominal pain and diarrhea after eating cold food).
• Internal cold—insufficient yang qi within the body, declining warming function. Yang deficiency (aversion to cold, cold limbs, listlessness), cold uterus (menstrual pain, irregular menstruation, infertility), cold stomach (stomach pain relieved by warmth, vomiting of clear water), kidney yang deficiency (weak knees and lower back, frequent nocturia).
So, the "cold" the ancients spoke of is not just low temperature, but a functional metaphor describing pathogenic characteristics—contraction, stagnation, and pain. The ancients used "cold" to summarize what modern people need multiple concepts like "vasoconstriction," "muscle spasms," "metabolic slowing," and "inflammatory mediator accumulation" to explain.
Alright, now let's translate "cold" into modern language.
I'm not going to talk about vasoconstriction, nerve conduction, or inflammatory mediators. Too complicated. You just need to remember one metaphor:
That's it. Your "cold," essentially, is a metaphor describing "low temperature causing physiological function suppression"—it emphasizes not the temperature itself, but the effect of temperature on physiological functions—contraction, stagnation, and pain.
Specifically:
What does external cold correspond to? It corresponds to the temperature stimulus response in modern medicine. Cold stimuli cause skin vasoconstriction (reducing heat loss), muscle contraction (generating heat), and pore closure (reducing evaporation). If these reactions are excessive, they lead to: colds (decreased immunity + viral invasion), frostbite (tissue ischemia and necrosis), and joint pain (increased synovial fluid viscosity + inflammatory response). External cold is not "cold evil" drilling into the body; it is the negative impact of low temperature on physiological systems.
What does internal cold correspond to? It corresponds to low metabolic function in modern medicine. Yang deficiency corresponds to hypothyroidism (decreased metabolic rate), autonomic nervous system dysfunction (thermoregulatory disorder), and anemia (insufficient heat production). Cold uterus corresponds to insufficient pelvic blood flow and low endometrial function. Cold stomach corresponds to reduced gastric mucosal blood flow and decreased digestive function. The essence of internal cold is low metabolic and circulatory function—the body's insufficient "heat production" and "transport" capacity.
What does "where there is pain, there is blockage; where there is free flow, there is no pain" correspond to? It corresponds to ischemic and hypoxic pain. Vasoconstriction causes reduced tissue blood flow, cellular hypoxia, and accumulation of metabolic products (lactic acid, bradykinin, substance P), stimulating nerve endings and producing pain. Hot compresses or exercise cause blood vessel dilation, improved blood flow, and removal of metabolic waste, relieving pain. This is the scientific basis of "where there is free flow, there is no pain"—not "qi is flowing," but blood is flowing, oxygen supply is adequate, and metabolic waste is cleared.
So, "cold" is not mysticism. It is a functional metaphor—describing the suppression of physiological functions by low temperature. The ancients used "cold" to summarize what modern people need multiple concepts like "vasoconstriction," "muscle spasms," "metabolic slowing," and "inflammatory mediator accumulation" to explain.
Real-Life Cases
Four vignettes to instantly show you what "cold" really is.
Case One: Joint Pain in Winter.
Your knees ache faintly in winter, getting worse with cold and easing with a hot compress. The doctor says: "Cold evil stagnates, blocking the meridians."
The truth: Cold stimuli cause vasoconstriction around the joints, increased synovial fluid viscosity, and reduced blood supply to joint cartilage. At the same time, cold causes muscles and ligaments to stiffen, increasing friction during joint movement. Accumulation of metabolic products stimulates nerve endings, producing pain. Hot compresses cause vasodilation, restore synovial fluid fluidity, and relieve pain. It's not "cold qi in the joints"; it's the physiological changes in blood vessels, synovial fluid, and muscles caused by low temperature. But the metaphor of "cold stagnation" accurately describes this process.
Case Two: Diarrhea from Eating Ice Watermelon.
In summer, you eat a big bowl of ice watermelon, and your stomach immediately cramps, sending you running to the bathroom. The doctor says: "Cold evil directly strikes, damaging spleen yang."
The truth: Cold drinks cause gastric mucosal and intestinal mucosal vasoconstriction, reduced digestive juice secretion, and disturbed intestinal peristalsis (first slowing, then accelerating). Low temperature also stimulates the intestinal vagus nerve, causing intestinal spasms and increased secretion. The result is abdominal pain and diarrhea. It's not "cold evil entered the spleen"; it's the direct stimulus of low temperature on the digestive system. But the description of "cold evil directly striking" vividly illustrates how cold drinks directly harm the digestive system.
Case Three: Cold Uterus Menstrual Pain.
During your period, you eat cold food, and your lower abdomen throbs with pain, as if there's a block of ice inside. The doctor says: "Cold uterus with blood stasis, where there is blockage, there is pain."
The truth: Cold stimuli cause pelvic vasoconstriction and reduced uterine blood flow. The endometrium becomes ischemic and hypoxic, prostaglandin secretion increases, causing strong contractions of uterine smooth muscle (dysmenorrhea). Hot compresses or drinking hot water cause pelvic vasodilation, improved blood flow, and relaxation of uterine smooth muscle, relieving pain. It's not "there's cold qi in the uterus"; it's pelvic vasoconstriction and uterine smooth muscle spasms caused by low temperature. But the metaphor of "cold uterus" accurately describes this pathological process.
Case Four: Granny's Cold Hands and Feet.
Your grandmother has cold hands and feet in winter; even with two quilts, she can't warm up. The doctor says: "Yang deficiency with severe cold, the limbs lose warmth."
The truth: Elderly people have enhanced peripheral vasoconstrictor responses, reducing skin blood flow. Thyroid function may be decreased, lowering basal metabolic rate. Autonomic nervous regulation function declines, and thermoregulatory capacity decreases. Anemia or malnutrition may also lead to insufficient heat production. Cold hands and feet are a combined result of insufficient metabolic heat production + peripheral vasoconstriction + declining thermoregulatory function. It's not "yang qi is deficient," but the metaphor of "yang deficiency" vividly describes the decline in metabolic and circulatory functions.
Four cases, one underlying logic: cold is not the temperature itself, but the suppression of physiological functions by low temperature—contraction, stagnation, and pain.
Modern Research
Are there scientific studies on "cold"?
Yes, and there are many. Scientists don't use the word "cold"; they use:
• Vasoconstriction and blood flow. Cold stimuli cause vasoconstriction through the sympathetic nervous system, reducing skin blood flow by more than 80%. Tissue ischemia leads to hypoxia, accumulation of metabolic products, and release of inflammatory mediators, producing pain. This is the scientific basis for "cold has the nature of stagnation and causes pain." Research shows that Raynaud's patients (fingers turn white and painful when exposed to cold) have abnormally sensitive finger vasoconstrictor responses. It's not "cold evil stagnates," but ischemic pain caused by excessive vasoconstriction.
• Low temperature and digestion. Animal experiments show that gastric perfusion of 4°C cold water can reduce gastric mucosal blood flow by 40%, decrease gastric acid secretion, and delay gastric emptying. After intestinal mucosa is exposed to cold, peristalsis is first inhibited and then increased, with secretion increasing. This is the scientific basis for "cold evil directly strikes, damaging spleen yang." It's not "cold evil harmed the spleen," but the direct physiological impact of low temperature on the digestive system.
• Temperature and inflammation. Cold environments can activate certain inflammatory pathways (such as the NLRP3 inflammasome), increasing the release of pro-inflammatory factors. After joints are exposed to cold, chondrocyte metabolism slows, and inflammatory factors (IL-1β, TNF-α) accumulate in the joint fluid, intensifying pain. Hot compresses increase blood flow, accelerate the removal of inflammatory factors, and relieve pain. This is the scientific basis for "where there is free flow, there is no pain"—not "qi is flowing," but blood flow improves, inflammatory mediators are cleared, and pain is relieved.
These studies fully demonstrate that "cold" is a system that can be precisely described using modern scientific language. The ancients used "cold" as a summary; modern people use "vasoconstriction," "muscle spasms," "metabolic slowing," and "inflammatory mediator accumulation" to describe it—they are talking about the same pathogenic mechanism.
Practical Methods
Now that you understand "cold," how do you use this knowledge?
First, dispel a few misconceptions:
• Eating ginger can expel all cold. Ginger can indeed dilate blood vessels and promote digestion, but "expelling cold" is not a universal remedy. During heat conditions (inflammation, infection), eating ginger may worsen symptoms. Ginger is "warm," not "universal."
• Hot foot baths cure all diseases. Hot foot baths can dilate foot blood vessels and improve peripheral blood flow, effective for cold hands and feet and mild fatigue. But they cannot treat diabetic foot (risk of burns), varicose veins (may worsen), or severe heart disease (may increase cardiac burden). Understanding the indications is more important than blindly "expelling cold."
Specific methods:
• Keep warm (prevent external cold). In winter, pay attention to keeping the head, neck, and feet warm. The head accounts for 30% of the body's heat loss, the neck has large blood vessels, and the feet are the farthest from the heart. Wear a hat, a scarf, and thick socks—not "old-fashioned," but "scientific cold prevention." TCM says "cold rises from the feet"—when the feet get cold, blood vessels throughout the body constrict.
• Avoid cold drinks (protect the spleen and stomach). Especially on an empty stomach, during menstruation, or after exercise—don't drink cold beverages. Cold drinks cause gastric mucosal vasoconstriction, reduced digestive juice secretion, and gastrointestinal dysfunction. TCM says "cold form and cold drink harm the lungs"—cold food and drinks harm the digestive system. Modern medicine confirms that when stomach temperature drops, digestive enzyme activity decreases, and gastrointestinal peristalsis becomes disturbed.
• Hot compress (where there is free flow, there is no pain). For joint pain, menstrual pain, and cold stomach pain, hot compresses are an effective way to relieve pain. Hot compresses cause local vasodilation, increased blood flow, removal of metabolic waste, and muscle relaxation. It's not "hot air driving away cold qi," but improved blood flow, restored oxygen supply, and pain relief. But the temperature shouldn't be too high (40–45°C is appropriate), and the duration shouldn't be too long (15–20 minutes).
• Moderate exercise (generating heat and unblocking yang). Exercise is a natural way to "expel cold." During exercise, muscle heat production increases, blood vessels dilate, blood flow accelerates, and metabolism rises. TCM says "movement generates yang"—exercise doesn't directly "expel cold," but improves the "cold stagnation" state by increasing metabolism and blood flow. 3–5 sessions of moderate-intensity exercise per week, 30 minutes each time.
• Warm-tonifying diet (supporting yang qi). People with yang deficiency constitution (cold-aversion, cold limbs, low energy) can appropriately eat warm-tonifying foods: lamb, ginger, jujubes (Chinese red dates), and longan. These foods are rich in calories, iron, and B vitamins, which can improve metabolism and blood circulation. It's not that "food has yang qi," but that nutrition supports metabolism, and calories support body temperature. But during heat conditions or inflammation, warm-tonifying is not appropriate.
These methods don't require you to believe in TCM. You just need to understand: cold is not the temperature itself, but the suppression of physiological functions by low temperature—contraction, stagnation, and pain. Preventing and managing this suppression is "expelling cold."
One-Minute Summary
🕐 One Minute to Understand "Cold"
Cold = Ice sculptor / freezer, a stagnating evil that causes pain.
Cold contracts and stagnates—it's not low temperature, but the suppression of physiological functions by low temperature.
External cold = external low temperature stimulus; internal cold = insufficient yang qi, low metabolic and circulatory function.
Cold = vasoconstriction + muscle spasms + metabolic slowing + inflammatory mediator accumulation.
Cold is not mysticism; it's a metaphor describing the physiological effects of low temperature.
Causes: treating cold as a physical entity, over-reliance on "cold-expelling" folk remedies, warm-tonifying during heat conditions, neglecting the root cause.
Methods: keep warm (prevent external cold), avoid cold drinks (protect the spleen and stomach), hot compress (where there is free flow, there is no pain), moderate exercise (generating heat and unblocking yang), warm-tonifying diet (supporting yang qi).
The ancients called it "cold has the nature of stagnation and causes pain"; modern people call it "vasoconstriction + ischemia and hypoxia + accumulation of metabolic waste."
Different names, but the body knows: cold is not the enemy; the contraction and stagnation it brings are.
xiaokz 小筷子 · Concept 42
Using the language of modern science to help the world understand Chinese traditional wisdom.
No mysticism, no superstition, no belittlement.
Understanding, not just believing.