Cough With Phlegm That Just Won’t Go Away? — Doctor Luo Dalun: Distinguish Cold From Heat, and the Right Medicine Picks Itself

💬 Note from Doctor Luo: Dear friends, good morning. This is the first recording of the new year, and I apologize for recording it so late. During the holiday our housekeeper was off, so I took care of my grandmother and my mother — three meals a day and all the chores of daily life. Now I know: none of us should look down on housework. Some women cook three meals a day for the family, and let me tell you, it really is an exhausting job. I’m not much of a hand at it, so I was worn out — the tea garden, cooking, prepping ingredients, grocery shopping, it was very hard work. Once the holiday was over and the housekeeper came back, I sent my elderly mother to the seaside. That’s when I realized I needed rest — during that whole time I hadn’t rested at all; it was mental exhaustion. I think this is what life is: everything is a form of cultivation. Whatever you encounter is a test and a chance to grow, so I am very happy to accept these challenges.

Opening: after COVID, why does the cough with phlegm never seem to end?

After the new year, work officially begins, and Doctor Luo continues to share Chinese medicine knowledge. Today’s topic: after COVID, many friends keep coughing with phlegm, often saying “it’s been a long time and there’s still phlegm.” What’s going on?

💬 Note from Doctor Luo: Let’s talk about phlegm in Chinese medicine. Chinese medicine distinguishes visible phlegm (you xing zhi tan) from invisible phlegm (wu xing zhi tan). Visible phlegm is what you can see — for example, when you cough something up and see it, we call that visible phlegm. Invisible phlegm is the sticky fluid your body produces that has not been expelled; wherever it lodges, it blocks the movement of qi and blood. Chinese medicine calls this invisible phlegm — though in fact it is also a tangible substance. Visible and invisible phlegm share exactly the same root cause; it’s just that during an external contraction, there may be more visible phlegm. In daily life, when the spleen loses its healthy transport function (jian yun) and the kidney loses its qi-transformation function (qi hua), fluids are retained, slowly congeal, and combine with metabolic waste to form invisible phlegm — that may be more common. But the root is the same; when this invisible phlegm is gradually expelled through the digestive tract, it becomes visible phlegm.

Why does phlegm cause coughing and wheezing?

When phlegm blocks the throat, the airways, and the respiratory tract, it causes coughing — and the two echo each other.

💬 Note from Doctor Luo: We need to stop the cough and calm the wheeze — because sometimes phlegm blocks the respiratory tract, even blocking the finest passages, and causes wheezing; further spasm of the airways also causes wheezing. That’s why stopping cough, calming wheeze, and resolving phlegm are usually treated together.

So how do we adjust? Doctor Luo says, the single most important thing is to distinguish cold from heat.

💬 Note from Doctor Luo: This confused me badly when I was first studying Chinese medicine. Just after learning the medicine — a person has a cough, we have all these herbs, we should give them and see results. But there was no effect at all. That made a deep impression on me: at the time I used every cough-suppressing and phlegm-resolving herb I knew — why didn’t it work? I was very curious. Later I understood: you have to distinguish cold from heat. Herbs also have cold and warm natures. Match them correctly — heat conditions get cooling herbs, cold conditions get warming herbs — and the effect is immediate. What does Chinese medicine talk about? It talks about pattern differentiation (bian zheng). If you don’t differentiate patterns, you assume all these herbs stop cough and calm wheeze and pile them all on — that’s actually wrong. Quite a lot of people never grasp this. From then on I insisted on treating the cold–heat distinction as a top priority.

A true story: the child’s cough wouldn’t heal — why did yours work right away?

Doctor Luo tells a case that impressed him deeply — back in Beijing, something a parent said made him think for a long time.

💬 Note from Doctor Luo: A parent said to me: “Teacher Luo, you all studied the same Chinese medicine.” I asked what he meant. He said: “Why didn’t my child’s cough get better after I treated it for so long, yet the moment you saw him, it worked?” That suddenly gave me pause — many people are trapped in routine formulas and disdain distinguishing cold from heat, as if it isn’t that fast. They look at a child coughing with phlegm and pile on every cough-suppressing and phlegm-resolving herb at once. If you don’t distinguish cold from heat, it won’t work — the fundamentals are unclear. You may use many herbs afterward and think they work, but they truly don’t. This impressed me deeply. Distinguishing cold from heat is the basic skill of all Chinese medicine — no matter how skilled you are or how long you’ve studied, you must carefully differentiate, for every single patient. Different stages bring changes in cold and heat; when evil qi arrives there are different reactions, with cold–heat changes.

How was that child cured? Doctor Luo says the key was observation:

💬 Note from Doctor Luo: The parent brought the child over. The child was playing nearby, and I kept observing — I never made a diagnosis, just watched. Until the child had a violent coughing fit and coughed up a mouthful of phlegm. I looked: the phlegm was yellow — that means there was inflammation in the airways, a heat pattern. So I gave cooling herbs, and it worked immediately. Now, can you observe that in the two or three minutes of a clinic visit? You need to observe on your own — in daily life. When you collect it, take a photo with your phone, then you know this is yellow phlegm, that is white phlegm. After observing, you provide the information to your doctor. Most people I meet — “my child is coughing,” “my family member is coughing” — don’t provide anything at all. Ask what color the phlegm is: “I don’t know yellow from white.” This is the first thing to observe: the color of the phlegm. That’s first-hand data.

How to judge cold from heat? Four observation points plus whole-body signs

How do you make a rough cold–heat judgment? Doctor Luo gives a concrete method — in most cases, look at these:

💬 Note from Doctor Luo: First, distinguish by phlegm color. In most cases, yellow phlegm means heat; white phlegm means cold. That’s the general rule — occasionally during an external contraction, if the contraction progresses too quickly, heat may be present before the phlegm turns yellow, and you’ll see white phlegm — but that’s very brief. As long as it slows down a little and lasts a little longer, the color of the phlegm that comes out is very important. If you haven’t seen the phlegm, your judgment can sometimes go wrong. So the first thing to observe is phlegm color. Ninety percent of people come to me and say “treat my cough”; I ask what color the phlegm is — “I don’t know, I don’t know.” “Go home and look; tell me in a day or two” — so you must observe in advance.

Second, look at the tongue body. If the edges and tip of the tongue are red, there is heat; if the tongue edges and the whole tongue are pale white — aside from the coating, the tongue body itself is all pale — there is likely cold. With heat, the coating may turn yellow sometimes, or may not, but the color of the tongue body is important: reddish or pale — that expresses cold and heat.

Third, look at the nasal discharge. Whether the nasal discharge is yellow or white can also distinguish cold from heat.

Fourth, feel the pulse and look at the whole. If the pulse beats fast, there is heat inside. People with heat show heat throughout: fever, flushed face, red eyes, yellow urine, and dry, bound stool. Cold conditions show chills all over, a pale complexion, terribly cold when the wind blows, clear and profuse urine, loose stools easily, and great fear of cold.

💬 Note from Doctor Luo: This rough distinction of cold and heat by constitution needs slow experience to master. Why are some Chinese medicine doctors so accurate? Because they’ve distinguished cold from heat for a long time, every day. Those who see little can’t tell the difference. Ordinary people always say “I can’t tell cold from heat” — because they see too little. So build your own model — observe yourself at any time. What do you look like when hot? What changes when you get hotter? You’ll learn gradually. When you’re not in a heat state, look at your tongue — what color, what condition — and remember it. Then in the last couple of days, why has it turned a bit red? Why does your throat hurt a little? Why are the tongue edges red? Then you know this is heat. Judge and learn on your own, step by step.

Even the famous doctors of antiquity stumbled on cold and heat

This matter of distinguishing cold from heat — even many ancient doctors tripped over it.

💬 Note from Doctor Luo: Look at the ancient physicians: many of them also failed to distinguish cold from heat. Li Dongyuan treated a child — it was clearly a cold pattern, but someone saw the red eyes and red face and said, isn’t that heat? That was floating yang escaping outward (xu yang wai yue) — in fact still a cold pattern. So Li Dongyuan used warming-yang herbs and the child recovered; otherwise the child would have been lost. This shows that many physicians of that era also couldn’t distinguish cold from heat. Distinguishing cold and heat, like distinguishing yin and yang, is the opening skill of Chinese medicine. If you’re careless and can’t judge clearly, your prescriptions will certainly be wrong. So when that parent asked “you all studied the same Chinese medicine, right?” — yes, the same Chinese medicine. It comes down to how well you grasp the theoretical system; you need to get that clear.

Cold phlegm — what to do? A checklist of warming phlegm-resolving herbs

Within cold and heat, what do we use for each? Doctor Luo gives a rough breakdown. Cold patterns: the phlegm is white — like egg white, some like thick white latex paint, some like foam; that kind of heavy phlegm-dampness, cold-dampness. The tongue is pale, very white, with teeth marks and much saliva — clearly yang deficiency with water flooding. The complexion is pale and the body feels cold — this is a yang-deficiency pattern with obvious cold evil. In this case use warming herbs. What warming herbs resolve phlegm and calm wheezing?

💬 Note from Doctor Luo: The first is ban xia (pinellia). We always use processed ban xia — fa ban xia (processed with licorice and lime), jiang ban xia (processed with ginger), and so on. Ban xia is a warming herb that dries dampness and resolves phlegm. What else? tian nan xing (arisaema) — slightly toxic, bitter, pungent, warm; its warm-drying nature exceeds ban xia’s. In some prescriptions you’ll see tian nan xing; it’s usable. Then bai jie zi (white mustard seed), su zi (perilla seed), and lai fu zi (radish seed) — put these three together and you have San Zi Yang Qin Tang (Three-Seed Decoction for Nourishing Parents). Bai jie zi is pungent; pungent-warm, it resolves phlegm extremely well, especially phlegm within the channels — that cold phlegm lying under the ribs, between skin and membrane. People say nothing but bai jie zi can remove it. It excels at dissolving that kind of phlegm in the interstices of the body — cold phlegm. Su zi (the seed of perilla) also resolves phlegm, and lai fu zi is radish seed. All of these are warming.

Jie geng (platycodon) is also slightly warm — Doctor Luo emphasizes its role in the lung channel:

💬 Note from Doctor Luo: Jie geng is warm — slightly warm. It spreads the lung and regulates qi, carries the medicinal power upward, and moves qi upward; it opens the chest, regulates qi, and resolves phlegm. Generally we say jie geng mainly unblocks and moves qi, so it can be used for both cold and heat. But its own nature is slightly warm, especially suited to cold patterns and cold coughs. You can also use jie geng for heat patterns — it guides herbs into the lung channel and the upper burner; this effect is strong, moving upward. We call it the “boat herb” (zhou ji zhi yao) — like a little boat ferrying the medicine upward. Especially in treating lung abscess (fei yong) — when the lung grows abscesses or sores, lobar pneumonia and all kinds of severe lung-heat conditions — jie geng can also be added to drain pus outward. So jie geng plays a very big role in treating the lung channel. Treating COVID and pneumonia nowadays, jie geng is also a frequently used herb — I use it very often.

Xuan fu hua (inula flower, also called jin fei cao) is also warm, and its medicinal power moves downward:

💬 Note from Doctor Luo: Xuan fu hua’s power moves downward; it softens hardness and resolves phlegm, especially good for that sticky, gluey state, pressing it down. We say “all flowers rise; only xuan fu hua descends” — the nature of every flower is to move upward; xuan fu hua moves downward. When you encounter lung qi rebelling upward that won’t stop — a cough you can’t hold back — how do you make the lung qi descend? Use a little xuan fu hua; it has the function of pressing the lung qi downward. The jin fei cao sold in pharmacies today is the above-ground part of the inula plant; it also resolves phlegm, stops cough, and calms wheeze.

Then there’s bai qian (cynanchum) — slightly warm; we use it often. When you buy a patent medicine and see bai qian in the formula, you know it’s warm, often paired with warm herbs — for example bai qian with jing jie (schizonepeta), which disperses cold; for cold coughs and cold phlegm, such herbs are used. xing ren (apricot kernel) stops cough, calms wheeze, and regulates lung qi; the qi moves downward; its nature is bitter and slightly warm; usable in both cold and heat; it resolves phlegm very well — external-contraction coughs often add a little xing ren.

💬 Note from Doctor Luo: The classic formula Ma Xing Shi Gan Tang (Ephedra, Apricot Kernel, Gypsum, and Licorice Decoction) — Zhang Zhongjing’s formula: ma huang (ephedra) releases the exterior and disperses cold; what’s the xing ren for? To regulate and descend lung qi; add raw shi gao (gypsum) to clear lung heat; add gan cao (licorice) to harmonize the center. It’s a very classic formula. Zhang Zhongjing was especially skilled at using xing ren to descend lung qi, stop cough, calm wheeze, and resolve phlegm. There’s also bai bu (stemona) — in the old pharmacopoeia it’s slightly warm, enters the lung channel, has a moistening function; it can descend lung qi, regulate qi, and resolve phlegm; we use bai bu often. And zi wan (aster) and kuan dong hua (coltsfoot) — both carry a slight toxicity; zi wan is warm, kuan dong hua is also warm; both are flowers, both open and regulate lung qi and resolve phlegm. Generally people say they can be used for cold or heat, but I basically use them for cold patterns — when the person truly has a cold cough, white phlegm, and chills over the whole body, coughing without stop: what do I do? I use bai bu, zi wan, kuan dong hua and the like in very small amounts — for example 3 grams each. Don’t overdo it; use them gently. After a few days it resolves, and then stop. Don’t keep using them. chen pi (aged tangerine peel) is warm; ju hong (red tangerine peel) is warm — ju hong’s ability to disperse external cold is stronger, chen pi’s ability to regulate qi and harmonize the center is stronger; both are warm. Ju hong and chen pi can be used long-term, working gradually. Bai jie zi, zi wan, kuan dong hua — just use a little; they help scatter cold phlegm. Once the lung cold is relieved, that’s it — no need for more.

Hot phlegm — what to do? A checklist of cooling phlegm-resolving herbs

Remember the heat pattern signs: the phlegm is yellow, the tongue edges are red, the tongue is red, the body even carries a bit of heat — you often feel hot; urine is yellow and scanty; stool is easily dry and bound; the whole body shows heat. In this case clear lung heat and use cooling herbs.

💬 Note from Doctor Luo: Just now I said bai qian is warm; qian hu (peucedanum), by contrast, is cool — slightly cold. Qian hu can descend lung qi and resolve phlegm, but it’s cold, and it resolves phlegm-heat — the heat in the phlegm is dissolved away. Then there’s gua lou (trichosanthes fruit) — sometimes gua lou pi (the rind), sometimes whole gua lou. Gua lou is cold. It’s especially good at tipping heat outward; we call it di tan dao zhi — “wash away phlegm and guide out stagnation”: it clears the phlegm out, then clears the accumulated stagnation. It also moistens the intestines and unblocks stool — the lung and the large intestine are interior–exterior paired (fei yu da chang xiang biao li); when the lung is hot, the large intestine is also hot, and the stool is dry; gua lou unblocks the stool. So it’s a cooling herb that clears heat. Then there are the bei mu (fritillaria) — divided into chuan bei mu (Sichuan fritillaria) and zhe bei mu (Zhejiang fritillaria). Chuan bei mu is bitter and slightly cold; for dry phlegm (zao tan) you can use chuan bei — its heat-clearing effect is actually quite marked; in heat patterns, use chuan bei. Zhe bei mu is also cold, often used during external contractions; it resolves phlegm and also disperses accumulations — because various nodules caused by phlegm-fire can be spread apart. So in chronic conditions, for nodules and masses caused by heat, people often add zhe bei mu to help resolve phlegm and scatter the lump. Both chuan bei and zhe bei are cold and cool.

Zhu ru (bamboo shavings) and zhu li (bamboo sap) — everything from the bamboo plant is cool, and it resolves phlegm:

💬 Note from Doctor Luo: Xian zhu li kou fu ye (Fresh Bamboo Sap Oral Liquid) — I introduced it during the pandemic, and people used it a lot. When the phlegm is yellow — various kinds of yellow phlegm — zhu li quickly dissolves it, including phlegm-heat. Zhu ru is the shaved inner layer of bamboo, curled in little strips — that’s zhu ru. Zhu li is the water that drips out when you roast bamboo. There’s a story from the internet: a family got COVID, and the grandfather took a machete, cut a big bundle of bamboo, set it on fire, and gave the children the water that dripped from the burning bamboo — they drank it and got well. That’s clearing phlegm-heat; zhu li’s ability to clear phlegm-heat is extremely strong. For other diseases caused by phlegm-heat — stroke with fever, traumatic brain heat, and so on — it can all be used. So you should know: zhu ru and zhu li are cold and cool.

Then hai fu shi (pumice) and hai ge ke (clam shell) — also commonly used, herbs that clear heat and resolve phlegm. Here let me emphasize luo han guo (monk fruit):

💬 Note from Doctor Luo: Luo han guo is cool — sweet and cool, not severely cold. For a dry throat with a bit of heat, use luo han guo. In the Guangxi region there are all sorts of luo han guo preparations; you can also boil luo han guo water and drink it yourself — it’s quite sweet. Some beverages nowadays even use luo han guo extract sweetness to replace sugar. Luo han guo is cool and moistening; for dry, heat-dry conditions, use luo han guo to cool and moisten.

Sang bai pi (mulberry root bark) — the white bark of the mulberry root — is frequently used for lung heat:

💬 Note from Doctor Luo: If there’s lung heat and yellow phlegm, we often add a little sang bai pi. The ancients said, “to drain the excess of the lung, nothing but sang bai pi will do” — when you have lung heat, what can drain it away? Sang bai pi works extremely well. It’s cool — remember that. And pi pa ye (loquat leaf) — usually said to be bitter and neutral, but in fact it’s slightly cold. Pi pa ye should only be used when there’s heat: hot coughs, yellow phlegm — pi pa ye works very well. If you use pi pa ye for a cold condition, the effect is not so good. Why can’t people cure disease when they mix cold and heat together? I think the finer the distinction, the better. Pi pa ye comes honey-processed or raw; I used to always use raw pi pa ye, now it doesn’t matter — write pi pa ye, honey-processed or raw, both fine. Pi pa ye clears lung heat and descends lung qi — it moves downward. For phlegm-heat, you can use a little pi pa ye. I usually pair xing ren and pi pa ye together.

A practical combination: external contraction cough with yellow phlegm — match it this way for immediate results

So how do you actually use it? Doctor Luo gives a practical combination:

💬 Note from Doctor Luo: When you encounter an external contraction, the cough is obvious, and the phlegm is yellow — that means there’s a heat pattern inside. I often use heat-clearing, toxin-resolving herbs — such as jin yin hua (honeysuckle, also called shuang hua), lian qiao (forsythia), pu gong ying (dandelion), huang qin (scutellaria) — to clear lung heat; and as long as there’s a cough, I add a bit of xing ren — xing ren is warm, but it works for both cold and heat; it descends lung qi. But I always add pi pa ye and zhe bei mu — I definitely add these heat-clearing herbs. Pi pa ye and zhe bei mu plus xing ren — sometimes I use the xing ren, sometimes not — but once pi pa ye and zhe bei mu are in, the effect is immediate; the heat is quickly cleared. Usually you don’t even need zhu li — that’s when things got out of hand: the phlegm is obvious, big clumps of yellow phlegm — then use zhu li. At the very start, there’s no need to go straight to zhu li. Pi pa ye and zhe bei mu are heat-clearing and are what we use all the time; if lung heat is marked, add a little sang bai pi. This is distinguishing cold from heat. Then regulating becomes very easy.

Treating the root: strengthen the spleen and tonify the kidney — that’s where phlegm is truly resolved

Besides distinguishing cold and heat, Doctor Luo stresses that strengthening the spleen and tonifying the kidney is even more important.

💬 Note from Doctor Luo: Why do you have so much phlegm? Where is the root? We say the lung is the container that stores phlegm (fei wei chu tan zhi qi) — the lung is only the result; lots of phlegm in the lung is only the result. The spleen is the source that generates phlegm (pi wei sheng tan zhi yuan) — the root is here: if the spleen can’t control dampness, can’t keep upright qi sufficient, then fluids slowly congeal into phlegm, and the phlegm is born. The kidney is the root of phlegm generation (shen wei sheng tan zhi ben) — why are your spleen and stomach weak? Kidney qi insufficiency. So Chinese medicine also has the approach of tonifying the spleen and kidney to resolve phlegm and stop cough.

Closing: distinguish cold from heat, and you can pick medicine in the pharmacy at a glance

Today Doctor Luo mainly taught everyone to distinguish cold from heat, and introduced some herbs.

💬 Note from Doctor Luo: I’ve listed these herbs in a table; you can all see it. Once you know it, go to the pharmacy and look at which herbs are present in greater proportion — sometimes they’re mixed together; see which proportion is larger. Sometimes cold and heat are intermingled, without an obvious single pattern — but you must find the emphasis: am I mainly cold or mainly heat? When they’re mixed, if I grasp the main pattern clearly, the disease is easy to treat and the hit rate is high. If you haven’t misjudged — it’s clearly a cold pattern or a heat pattern — basically the prescription works immediately; pick any few of these herbs and it gets better right away. That’s the charm of Chinese medicine.

💬 Note from Doctor Luo: Today I taught you to distinguish cold from heat — the first lecture of the new year, and we’ve talked for almost half an hour. Thank you all for listening. In the future we’ll discuss these herbs in detail — just now I skimmed through, touching the names and the cold–heat nature of each. Later we can go through them one by one. That will give you better guidance for preventing external contractions and choosing medicines at the pharmacy. Dear friends, that’s all for today. Thank you for listening. Tomorrow we’ll share more Chinese medicine knowledge — see you tomorrow!

Compiled from Doctor Luo Dalun’s health lecture series (cough and phlegm series: distinguishing cold from heat to choose the right medicine).