A Comparative Study on the Understanding of "Fever" between Traditional Chinese Medicine and Western Medicine

The understanding of fever in Traditional Chinese Medicine (TCM) and Western Medicine presents a complementary relationship of "microscopic mechanism–macroscopic syndrome differentiation": Western medicine follows the causal chain of "pyrogen → thermoregulatory set point → fever," emphasizing precise etiological localization and quantitative grading; TCM follows the pathogenic chain of "external pathogen invasion → struggle between righteous qi and pathogenic factors → disharmony of Ying and Wei qi → fever," emphasizing dynamic comprehension of the body's overall state and progression trends. The following systematically compares these two paradigms across four dimensions: etiological mechanisms, syndrome differentiation systems, treatment strategies, and clinical integration.

1. Etiology and Pathogenesis: Theoretical Dialogue between Pyrogen Cascade Reaction and the Struggle between Righteous Qi and Pathogenic Factors

1.1 Western Medicine: From Pyrogens to the Thermoregulatory Set Point

Western medicine holds that the core mechanism of fever involves pyrogens acting on the hypothalamic thermoregulatory center, causing an upward shift of the thermoregulatory set point and resulting in an imbalance between heat production and heat dissipation.

Pyrogens are classified into two categories: exogenous pyrogens include various pathogenic microorganisms (bacteria, viruses, fungi, etc.) and their products, inflammatory exudates, sterile necrotic tissue, and antigen-antibody complexes, among others; endogenous pyrogens are produced by immune cells, primarily including interleukin-1 (IL-1), tumor necrosis factor (TNF), and interferons, and are also known as leukocytic pyrogens.

In addition, non-pyrogenic fevers exist, such as hyperthyroidism (excessive heat production), traumatic brain injury (central fever), heat stroke (impairment of heat dissipation), and acute myocardial infarction (absorption fever), among others.

1.2 Traditional Chinese Medicine: From External Pathogen Invasion to Disharmony of Ying and Wei

TCM holds that the fundamental pathogenesis of fever is the invasion of external pathogens into the human body, with the body's righteous qi rising to resist the pathogenic factors. The struggle between righteous qi and pathogenic factors at the body surface or within the zang-fu organs leads to disharmony of Ying and Wei qi and imbalance of yin and yang. External pathogens include the six excesses (wind, cold, summer-heat, dampness, dryness, and fire) as well as pestilential qi. TCM emphasizes that "when righteous qi is preserved within, pathogenic factors cannot invade"—whether fever occurs depends not only on the nature of the external pathogen but, more importantly, on the strength of the body's righteous qi and constitutional state.

1.3 Convergence Points of the Two Theories

The TCM theory of "struggle between righteous qi and pathogenic factors" closely resonates with Western immunology: when pathogens invade, macrophages release cytokines such as IL-1 and TNF-α, which prompt the hypothalamus to upregulate the thermoregulatory set point. A temperature elevation of 1–2°C can significantly enhance immune cell activity and inhibit viral replication—this precisely corroborates the TCM understanding that "fever is a manifestation of righteous qi overcoming pathogenic factors."

TCM's "disharmony of Ying and Wei" can be understood as dysregulation of the neuro-endocrine-immune network. Ying qi corresponds to the nutritional metabolism system, while Wei qi corresponds to the immune defense system; the two work synergistically to maintain the dynamic balance of metabolic-immune homeostasis.

2. Syndrome Differentiation Systems: Deep Comparison of Six-Meridian Differentiation, Wei-Qi-Ying-Blood Differentiation, and Fever Pattern Classification

2.1 Shanghan Theory: Six-Meridian Framework for Fever Differentiation

The Treatise on Cold Damage (Shanghan Lun) uses the Six Meridians as its framework, classifying exterior febrile diseases into six stages according to the depth of disease location and the relative strength of righteous qi versus pathogenic factors. The fever characteristics at each stage are distinctly different:

The transmission pattern of the Six Meridians closely corresponds to the natural course of infectious diseases: days 1–2 typically involve upper respiratory tract infections (Taiyang syndrome), days 3–4 may progress to pneumonia (Yangming syndrome), days 5–7 may present with systemic symptoms (Shaoyang syndrome), and severe cases may develop multiple organ dysfunction (the three Yin syndromes).

2.2 Wenbing Theory: Wei-Qi-Ying-Blood Framework for Fever Differentiation

In the Qing Dynasty, Ye Tianshi established the Wei-Qi-Ying-Blood (Defensive-Qi-Nutritive-Blood) syndrome differentiation system for warm-heat diseases, categorizing the depth of heat pathogens in the body into four levels:

Wei-level syndrome—pathogen in the Lung and Defensive level: fever, slight aversion to wind and cold, slight thirst, floating-rapid pulse. Treatment principle: acrid-cool exterior-release (Yinqiao San).

Qi-level syndrome—pathogen entered the Lung and Stomach: high fever, no aversion to cold but aversion to heat, profuse sweating, intense thirst, flooding pulse. Treatment principle: clear heat from the Qi level (Baihu Tang).

Ying-level syndrome—heat consuming Ying yin: worse fever at night, restlessness and insomnia, faint maculopapular rash, red-crimson tongue. Treatment principle: clear Ying level and vent heat outward (Qingying Tang).

Blood-level syndrome—disturbing blood and consuming blood: high fever with delirium, hematemesis and epistaxis, deep crimson tongue. Treatment principle: cool the blood and dispers stagnant blood (Xijiao Dihuang Tang).

Ye Tianshi's sixteen-character guideline—"When the pathogen is at the Wei level, sweating may resolve it; only when it reaches the Qi level should one clear heat; upon entering the Ying level, one may still vent heat outward; upon entering the Blood level, one must cool the blood and disperse stagnation"—embodies the dynamic thinking that as heat pathogens penetrate deeper, treatment strategies must correspondingly shift.

2.3 Correspondence between Western Medicine Fever Patterns and TCM Syndrome Differentiation

Western medicine classifies fever into six major patterns based on the morphological characteristics of the temperature curve, each corresponding to specific disease spectra:

Continued fever (temperature consistently 39–40°C, 24-hour fluctuation ≤1°C): commonly seen in lobar pneumonia, typhoid fever, etc.—corresponds to Yangming meridian syndrome in TCM (exuberant interior heat).

Remittent fever (temperature >39°C, 24-hour fluctuation >2°C): commonly seen in sepsis, suppurative inflammation—corresponds to exuberant heat in the Qi level or heat entering the Ying-Blood level in TCM.

Intermittent fever (alternating high fever and normal temperature): commonly seen in malaria, acute pyelonephritis—corresponds to the Shaoyang syndrome's "alternating chills and fever" in TCM.

Undulant fever (gradual rise and fall, recurring multiple times): commonly seen in brucellosis—corresponds to lingering damp-heat in TCM that is persistent and difficult to resolve.

Relapsing fever (high fever for several days then sudden drop, followed by another sudden rise after an interval): seen in relapsing fever, Hodgkin's disease—corresponds to repeated struggle between righteous qi and pathogens in TCM.

Irregular fever (no fixed pattern): seen in tuberculosis, rheumatic fever, cancer fever, etc.—corresponds to mixed deficiency and excess, complicated cold-heat patterns in TCM.

3. Treatment Strategies: Complementary Approaches of Syndrome Differentiation Treatment and Symptomatic Treatment

3.1 TCM: Same Disease, Different Treatments; Formula Adjustment According to Syndrome Changes

The core principle of TCM in treating fever is syndrome differentiation and treatment—the same "fever" may require completely different treatment approaches depending on the disease location, nature, and the patient's constitution. For example: a patient with chills, absence of sweat, headache, and body aches has a disease at the exterior level and should be treated with sweating and exterior-release (Mahuang Tang); a patient with high fever, constipation, abdominal distension, and dry mouth has a disease at the interior level and should be treated with purging the bowels and draining heat (Chengqi Tang). If the treatment approaches are reversed, not only will the fever not subside, but "complicated diseases" may arise—what modern medicine refers to as iatrogenic diseases, which are condition changes caused by inappropriate medical treatment.

TCM also emphasizes dynamic tracking of disease progression: disease is not static. A Shanghan disease may progress step by step from Taiyang to Yangming, Shaoyang, and even the three Yin meridians, or it may skip meridians in its transmission. Therefore, when responding to acute fever, TCM practitioners often prescribe formulas for only one day and re-evaluate the syndrome the following day based on changes in the condition.

3.2 Western Medicine: Concurrent Etiological Treatment and Symptomatic Management

Western medicine treatment of fever follows two pathways: first, etiological treatment—after identifying the pathogen, antibiotics, antiviral drugs, etc. are used to directly kill or inhibit the pathogen; second, symptomatic management—antipyretic and analgesic drugs (such as acetaminophen, ibuprofen) are used to lower the thermoregulatory set point, combined with physical cooling methods (tepid sponge baths, etc.) to prevent complications such as febrile seizures.

3.3 Classic Case: Insights from the 1954–1956 Japanese Encephalitis B Treatment

During the 1954 Japanese encephalitis B epidemic in Shijiazhuang, TCM practitioner Guo Keming and colleagues differentiated the syndrome as "heat predominating over dampness" and primarily used Baihu Tang and Qingwen Baidu Yin. All 34 patients were cured. In 1956, a similar outbreak occurred in Beijing, but applying the Shijiazhuang protocol yielded markedly reduced efficacy. Pu Fuzhou was called upon in the crisis and, through syndrome differentiation, determined that Beijing's continuous rainy weather indicated "equal severity of summer-heat and dampness." He switched to methods of resolving damp-heat and aromatic orifice-opening (Xingren Huashi Tang, Sanren Tang, etc.), and among 167 patients, none died—however, 98 different formulas were used, averaging fewer than two patients per formula.

This case profoundly reveals the fundamental differences between TCM and Western medical thinking: Western medicine asks "Is this Japanese encephalitis B?" and seeks one formula for one disease; TCM asks "What is this person's current state?" and tailors treatment to the individual, the timing, and the environment.

4. Towards Integration: Modern Practice of Integrating TCM and Western Medicine in Fever Diagnosis and Treatment

In modern clinical practice, the integration of TCM and Western medicine in treating fever has formed several mature models:

Sequential therapy: During acute high fever, Western symptomatic cooling (antipyretic analgesics + physical cooling) is administered first while completing examinations to identify the etiology; if bacterial infection is confirmed, antibiotics are combined with TCM herbs for clearing heat and detoxifying; if viral infection is confirmed, antiviral drugs are combined with TCM herbs for dispersing wind and releasing the exterior. Western medicine rapidly controls symptoms, while TCM regulates immunity and shortens disease duration.

Combined medication: Studies have shown that antiviral drugs combined with Lianhua Qingwen can accelerate relief of systemic symptoms such as high fever, sore throat, and fatigue, and reduce the conversion rate to severe disease.

Modern verification of formula mechanisms: The active components of Guizhi Tang can counteract the pyrogenic effects of various endogenous pyrogens including IL-1, TNF, and interferons; Mahuang Tang can significantly inhibit the TLR3, TLR4, and TLR7 signaling pathways and downregulate TNF-α levels; Xiaochaihu Tang not only reduces fever but also improves immune function status.

5. Conclusion

Facing the same "fever," Western medicine uses the thermometer as a measuring stick, following the causal chain of "pyrogen → cytokines → thermoregulatory set point → fever" to precisely localize the etiology; TCM uses the four diagnostic methods as tools, following the pathogenic chain of "external pathogen → struggle between righteous qi and pathogens → disharmony of Ying and Wei → Six-Meridian/Wei-Qi-Ying-Blood transmission" to dynamically comprehend the overall state. The two are not opposed but rather observe the same life phenomenon from different dimensions. The combination of Western medicine's precise quantification and TCM's holistic syndrome differentiation—capable of both rapidly controlling symptoms and identifying etiology, as well as tailoring treatment to the individual and adjusting dynamically—represents the future direction of fever diagnosis and treatment.