Pathological Product Variable Yin Internal

Phlegm as a pathological product

痰 Tán · Phlegm
Also known as: Tan · Phlegm-Dampness · Tan Yin · Turbid Phlegm

Phlegm (Tan) is a pathological product formed when the body's fluid metabolism becomes impaired, resulting in the accumulation and thickening of body fluids. It can be visible (as mucus) or invisible (causing various systemic symptoms), and once formed, becomes a secondary disease-causing factor.

Key Properties

Sticky and viscous Turbid and heavy Obstructive Lingering and difficult to resolve Can flow anywhere in the body Variable thermal nature

Season

Late Summer

Body Layers

Middle Jiao

痰

Tán

Phlegm

Nature & Properties

Thermal Nature

Variable

Yin-Yang

Yin

Season

Late Summer

Educational content · Consult qualified TCM practitioners for diagnosis and treatment

Overview

Phlegm (痰, Tán) is one of the most important pathological products in Traditional Chinese Medicine, formed when body fluids fail to be properly transformed and transported. Unlike the Western understanding of phlegm as simply respiratory mucus, TCM views phlegm as a complex pathological substance that can affect virtually any part of the body.

In TCM theory, phlegm is generated when the transformation and transportation functions of the Lungs, Spleen, and Kidneys become impaired. The classic saying "the Spleen is the source of phlegm production, while the Lungs are the receptacle that stores it" (脾为生痰之源，肺为贮痰之器) captures this relationship. When body fluids stagnate due to organ dysfunction, they can condense and thicken into phlegm over time.

TCM distinguishes between two types: visible phlegm (有形之痰, yǒu xíng zhī tán) which can be seen as sputum or felt as lumps, and invisible phlegm (无形之痰, wú xíng zhī tán) which causes symptoms like dizziness, mental fog, and various inexplicable conditions. The ancient saying "strange diseases are mostly due to phlegm" (怪病多痰) reflects phlegm's role in many complex, difficult-to-diagnose conditions.

Historical Context

The concept of phlegm has evolved significantly throughout Chinese medical history. Early references to fluid disorders appear in the Huangdi Neijing, but Zhang Zhongjing (c. 150-219 CE) in the Jin Gui Yao Lue systematically categorized phlegm-fluid disorders and established treatment principles that remain foundational today.

The Song Dynasty physician Yang Shiying (仁斋直指方论) first clearly distinguished between the thick, turbid nature of phlegm (痰) and the thinner quality of fluid retention (饮). During the Jin-Yuan period, Zhu Danxi (朱丹溪, 1281-1358) greatly expanded phlegm theory, emphasizing the Spleen's role and developing the treatment principle of strengthening Spleen function to address the root cause.

Later physicians increasingly recognized "invisible phlegm" as a cause of complex internal disorders beyond respiratory symptoms. This broader understanding led to the famous saying "strange diseases are mostly due to phlegm" (怪病多痰), acknowledging phlegm's role in mysterious conditions affecting the mind, nervous system, and various organs.

Defining Characteristics

Sticky and Viscous

黏滞

Phlegm has a thick, gluey quality that makes it difficult to expel and causes it to stick to tissues and channels. This stickiness leads to symptoms that are stubborn and hard to treat, as the phlegm adheres wherever it lodges.

Turbid

浊

Phlegm is characterized by cloudiness and impurity. When it affects the clear orifices (head, sense organs), it causes confusion, dizziness, and mental fogginess. This turbid nature contrasts with the clear, refined quality that healthy body fluids should have.

Heavy

重

Like dampness, phlegm has a heavy quality that weighs down the body and mind. Patients often report feelings of heaviness in the head, limbs, or chest. This weight can impair movement and mental clarity.

Obstructive

阻滞

Phlegm blocks the flow of Qi, blood, and body fluids through channels and organs. This obstruction can cause pain, masses, nodules, and functional impairment wherever the phlegm accumulates.

Mobile and Pervasive

流动无处不到

Once formed, phlegm can travel throughout the body following the Qi. It can lodge in any organ, tissue, or channel—from the skin surface to deep within organs, from the muscles to the bones. This accounts for phlegm's involvement in such a wide variety of conditions.

Entry Routes

Unlike external pathogens, phlegm is primarily generated internally rather than entering from outside. However, external factors can trigger its formation:

  • External dampness invasion: Can impair fluid metabolism and contribute to phlegm production
  • External pathogen affecting the Lungs: Wind-cold or wind-heat attacking the Lungs can impair their dispersing function, leading to fluid accumulation and phlegm
  • Dietary factors: Excessive consumption of cold, raw, greasy, or sweet foods damages Spleen function and promotes phlegm generation

Progression Pattern

Body Layers Affected

Middle Jiao

Phlegm typically develops and progresses through recognizable stages:

  1. Initial dampness accumulation: Fluid metabolism begins to slow, creating mild dampness symptoms like heaviness and digestive sluggishness
  2. Dampness condensing to phlegm: Over time, stagnant fluids thicken and condense into phlegm, becoming more substantial and obstructive
  3. Phlegm lodging in specific locations: Phlegm settles in organs, channels, or tissues, producing location-specific symptoms
  4. Phlegm combining with other pathogens: Phlegm commonly combines with heat (forming phlegm-heat), cold (cold-phlegm), or blood stasis (phlegm and blood stasis), creating more complex and stubborn conditions
  5. Chronic phlegm disorders: Long-standing phlegm becomes deeply entrenched, difficult to resolve, and may contribute to serious conditions

Clinical Relevance

In modern clinical practice, phlegm patterns are extremely common and clinically significant. Understanding phlegm pathology helps practitioners address conditions that might otherwise seem unrelated or mysterious.

Common clinical applications include:

  • Respiratory conditions: chronic bronchitis, asthma, COPD, and sinusitis with mucus production
  • Digestive disorders: nausea, poor appetite, and abdominal distension with a slippery pulse and greasy tongue coating
  • Mental-emotional conditions: anxiety, depression, bipolar disorder, and cognitive impairment attributed to phlegm misting the orifices
  • Cardiovascular conditions: atherosclerosis and coronary heart disease viewed as phlegm and blood stasis obstructing the Heart vessels
  • Metabolic disorders: obesity, hyperlipidemia, and metabolic syndrome often involve phlegm-dampness accumulation
  • Tumors and masses: many benign masses (lipomas, nodules, cysts) are attributed to phlegm accumulation

Diagnosis relies on the combination of a slippery pulse and greasy tongue coating as hallmark signs, along with symptoms of obstruction, heaviness, or turbidity.

Common Manifestations

Cough with Sputum

Productive cough with visible phlegm of varying color and consistency depending on whether it's cold-phlegm (white, thin) or heat-phlegm (yellow, thick)

Chest Oppression

A feeling of fullness, tightness, or stuffiness in the chest due to phlegm obstructing Lung and Heart function

Dizziness and Vertigo

Phlegm turbidity rising to cloud the clear orifices of the head, causing spinning sensations and mental fogginess

Nausea and Vomiting

Phlegm in the Stomach disrupts its descending function, causing rebellious Qi that manifests as nausea or vomiting of phlegm-fluid

Mental Confusion or Mania

Invisible phlegm misting the Heart orifices can cause symptoms ranging from brain fog to severe mental disturbance, including manic behavior (Dian Kuang)

Nodules and Lumps

Phlegm accumulating in soft tissues can form palpable masses, including scrofula (瘰疬), goiter (瘿瘤), lipomas, and other soft nodules

Numbness and Heaviness

Phlegm blocking channels causes numbness, tingling, or a heavy sensation in the limbs

Globus Sensation (Plum Pit Qi)

A sensation of something stuck in the throat that cannot be swallowed or coughed up, caused by phlegm and Qi stagnation

Tongue Manifestations

The tongue provides important diagnostic information for phlegm patterns:

  • Coating: The most characteristic sign is a greasy or slippery coating (腻苔). This coating appears smooth, sticky, and difficult to scrape off
  • Coating color: White greasy coating suggests cold-phlegm or damp-phlegm; yellow greasy coating indicates phlegm-heat
  • Coating thickness: Thick coating indicates more severe or deeply lodged phlegm
  • Tongue body: May be swollen with teeth marks (indicating Spleen Qi deficiency failing to transform fluids)
  • Tongue color: May be pale (cold-phlegm with Yang deficiency) or red (phlegm-heat)

Pulse Manifestations

Pulse qualities associated with phlegm conditions include:

  • Slippery pulse (滑脉, Huá mài): The most characteristic pulse for phlegm—feels smooth and round, like pearls rolling under the fingers. This is the hallmark sign of phlegm or dampness in the body
  • Wiry pulse (弦脉, Xián mài): Often accompanies phlegm when there is Liver involvement or Qi stagnation combined with phlegm
  • Deep pulse (沉脉, Chén mài): May indicate phlegm-fluid (Yin) retention, especially when combined with slippery quality
  • Soft/Soggy pulse (濡脉): Indicates dampness transforming into phlegm with underlying deficiency

Common Pathogen Combinations

The most common combination, as dampness is the precursor to phlegm. Phlegm-dampness is heavy, sticky, and particularly affects the Spleen and digestive system. Symptoms include abdominal bloating, loose stools, fatigue, and a heavy sensation throughout the body. The tongue coating is white, thick, and greasy.

When phlegm combines with heat or when phlegm itself generates heat through prolonged stagnation. Characterized by yellow, thick, sticky sputum, fever, thirst, irritability, and a red tongue with yellow greasy coating. Common in acute respiratory infections and inflammatory conditions.

Phlegm and Blood Stasis (痰瘀互结)

Combined with Blood statis as a pathological product

A serious and stubborn combination where phlegm and stagnant blood become intertwined. Creates fixed masses, nodules, and tumors. Associated with conditions like atherosclerosis, stroke, and certain cancers. Symptoms include fixed stabbing pain, palpable masses, and purple discoloration. Very difficult to treat and requires addressing both pathological products simultaneously.

Phlegm combined with internal wind, often seen in conditions like stroke, epilepsy, and tremors. Symptoms are characterized by sudden onset, movement (convulsions, trembling), and unpredictability. May present with dizziness, numbness, facial paralysis, or loss of consciousness.

Phlegm with cold characteristics, often due to Yang deficiency failing to warm and transform fluids. The phlegm is white, clear, thin, and easy to expectorate. Patients feel cold, prefer warm drinks, and have a pale tongue with white slippery coating. Common in chronic bronchitis with Yang deficiency.

Differentiation from Similar Pathogens

Phlegm vs. Dampness: Both arise from impaired fluid metabolism, but dampness is more diffuse and foggy, while phlegm is more condensed and substantial. Dampness causes heaviness and sluggishness; phlegm causes obstruction and masses. "Dampness is the mother of phlegm"—dampness can develop into phlegm over time.

Phlegm vs. Fluid Retention (饮, Yǐn): Both are pathological fluid accumulations, but phlegm is thicker and more turbid, while fluid retention (Yin) is thinner and more watery. Fluid retention tends to stay in specific body cavities (stomach, chest, hypochondrium), while phlegm can travel anywhere.

Phlegm vs. Water Swelling: Water swelling manifests as edema with pitting, while phlegm creates masses, nodules, or obstructive symptoms without pitting edema. Water is the clearest, followed by fluid retention, then phlegm as the most turbid.

Visible vs. Invisible Phlegm: Visible phlegm can be seen (sputum) or felt (nodules). Invisible phlegm is diagnosed through its effects: mental symptoms, dizziness, and strange or difficult-to-explain conditions, combined with a slippery pulse and greasy tongue coating.

Treatment Principles

Treatment of phlegm requires addressing both the manifestation (branch) and the root cause:

  • Transform phlegm (化痰, huà tán): The primary approach using herbs and acupuncture that directly resolve phlegm accumulation
  • Strengthen the Spleen (健脾): Essential for preventing new phlegm formation—"treat phlegm by treating the Spleen." As Zhu Danxi stated: "Treatment of phlegm should fortify the Spleen earth and dry Spleen dampness—this treats the root"
  • Regulate Lung Qi (宣肺): Restore the Lungs' dispersing and descending functions to prevent fluid accumulation
  • Warm Yang (温阳): For cold-phlegm patterns, warm Spleen and Kidney Yang to enhance fluid transformation
  • Clear heat (清热): For phlegm-heat patterns, clear heat while transforming phlegm
  • Move Qi (行气): Qi movement helps transport and transform phlegm—"treat phlegm by first treating Qi"
  • Invigorate blood (活血): When phlegm and blood stasis combine, both must be addressed

Representative Formulas

Er Chen Tang

The foundational formula for transforming phlegm and drying dampness, treating the Spleen to address the root of phlegm production

Wen Dan Tang

Clears phlegm-heat from the Gallbladder and Heart, used for anxiety, insomnia, and mental restlessness due to phlegm-heat disturbing the spirit

Ban Xia Bai Zhu Tian Ma Tang

Treats dizziness and vertigo caused by wind-phlegm rising to disturb the head

Di Tan Tang

A stronger phlegm-transforming formula for stubborn phlegm blocking the channels and orifices

Ling Gui Zhu Gan Tang

Warms Yang and transforms phlegm-fluid, especially for fluid retention in the chest with palpitations

Representative Points

ST-40

Fenglong

The empirical point for phlegm—transforms phlegm and dampness throughout the body regardless of location. As the Luo-connecting point of the Stomach channel, it strengthens the Spleen and resolves both visible and invisible phlegm
REN-12

Zhongwan

Front-Mu point of the Stomach, strengthens Spleen and Stomach function to address the root of phlegm production
REN-22

Tiantu

Descends Lung Qi, benefits the throat, and resolves phlegm accumulation in the chest and throat
PC-6

Neiguan

Opens the chest, calms the Heart, and descends rebellious Qi; often combined with ST-40 for chest oppression and anxiety from phlegm
SP-6

Sanyinjiao

Strengthens the Spleen and resolves dampness, addressing the root cause of phlegm formation

Classical Sources

Jin Gui Yao Lue (金匮要略)

Chapter 12: Phlegm-Fluid Cough Disease

问曰：夫饮有四，何谓也？师曰：有痰饮，有悬饮，有溢饮，有支饮

Question: There are said to be four types of fluid retention—what are they? The Master said: There is phlegm-fluid retention, suspended fluid retention, overflowing fluid retention, and supporting fluid retention

Dan Xi Xin Fa (丹溪心法)

Chapter on Phlegm

治痰之法，实脾土，燥脾湿，是治其本

The method for treating phlegm is to strengthen the Spleen earth and dry Spleen dampness—this treats the root

Za Bing Yuan Liu Xi Zhu (杂病源流犀烛)

Phlegm-Fluid

痰为诸病之源，怪病皆由痰成也

Phlegm is the source of various diseases; strange diseases are all caused by phlegm

Jing Yue Quan Shu (景岳全书)

Discussion on Phlegm

脾家之痰，则有虚有实，如湿滞太过者，脾之实也；土衰不能制水者，脾之虚也

Phlegm of the Spleen has both excess and deficiency types: when dampness stagnation is excessive, this is Spleen excess; when Earth is weak and cannot control water, this is Spleen deficiency

Modern References

Recent Advances and Perspective of Studies on Phlegm Syndrome in Chinese Medicine

PMC/NIH Research Review (2016)

Comprehensive review examining the biological basis of phlegm syndrome and its relationship to modern disease categories including cardiovascular disease and stroke

The Foundations of Chinese Medicine

Giovanni Maciocia (2015)

Detailed discussion of phlegm as a pathological product, including differentiation of phlegm types and treatment strategies

Chinese Herbal Medicine: Materia Medica

Dan Bensky, Steven Clavey, Erich Stöger (2004)

Comprehensive reference for herbs that transform phlegm with clinical applications and traditional usage