寒热往来与发热恶寒异∶发热恶寒，一时兼至；寒热往来，寒已方热，热已方寒。亦与疟不同∶疟发有
时，寒热长短有定；此则寒热无时，长短无定。虽不同于疟，而邪俱在少阳半表半里之间。
在传变之初，是由轻入重，始则寒热往来，继则热多寒少，再则但热不寒，至昼夜壮热、谵妄、烦渴毕现。在
传变之后，是由重出轻，昼夜壮热，渐减而为发热，有时而止，又减而为寒热往来，又减而为战汗，至脉静身凉而愈。
夫疫邪自里出表者轻，自表入里者重。初起寒热往来，是自表入里，犯及少阳，里气与邪相争拒，继则邪深
入里，表里并而为热，昼夜壮热而势日重。既传变之后，而寒热往来，是邪气向衰，正气来复，自里出表，经过少
阳。前之昼夜壮热，邪气秉纲者，至此正气渐和而寒热有时矣。前之邪阳独盛，亢极无阴作纯热者，至此则阴气来
复而寒热相争矣。前之邪并表里而热渴日加者，至此则里气逐出表邪而作战汗矣。治法于未传变之先，欲由表入里
时，但透达其邪，使易传化为主，达原饮是也。于传变之后，欲自里出表时，以和解为主，小柴胡汤是也。于屡经
汗下之余，脉或虚微、濡弱、结代，心或悸动，神或委倦，形或羸弱过甚，当养阴益气，助正却邪为主，参胡三
白汤、炙甘草汤、清燥养荣汤、补中益气汤是也。（濡同软。）
寒热往来与发热恶寒不同：发热恶寒是同时出现；寒热往来则是先感到寒冷，冷过之后才发热，热退之后才又感到寒冷。这也与疟疾不同：疟疾发作有固定的时间，发冷和发热的持续时间也是确定的；而此病则没有固定的发作时间，发冷和发热的长短也不确定。虽然不同于疟疾，但邪气都位于少阳经的半表半里之间。
在疾病传变的初期，病情是由轻转重，起初表现为寒热往来，接着变为热多寒少，再后来变成只有发热而没有恶寒，直到昼夜持续高热、胡言乱语、烦躁口渴等症状全部显现。在疾病传变之后，病情是由重转轻，昼夜持续的高热逐渐减轻变为发热，有时停止，进一步减轻变为寒热往来，再进一步减轻变为战汗（一种先战栗后出汗的症状），直到脉象平静、身体凉爽而痊愈。
疫邪从体内向体表透发的属于轻证，从体表向体内深入的重证。初起时的寒热往来，是邪气由表入里，侵犯少阳经，体内的正气与邪气相互抗争排斥，接着邪气深入体内，表里之气共同化热，导致昼夜高热且势头日益加重。经过传变阶段后的寒热往来，说明邪气正在衰退，正气开始恢复，病邪从体内向体表透发，经过少阳经。之前的昼夜高热，是因为邪气占据主导，至此正气逐渐调和，所以寒热发作有了定时。之前的邪热独盛，亢极无阴，表现为纯粹的发热，至此阴气来复，所以出现寒热相争的现象。之前的邪气并合表里，导致热渴日益加重，至此体内正气驱逐表邪外出，从而发生战汗。治疗方法在未传变之前，当邪气欲由表入里时，以透达邪气，使其容易传变化解为主，方用达原饮。在传变之后，当邪气欲自里出表时，以和解少阳为主，方用小柴胡汤。在多次经过发汗、攻下治疗之后，如果脉象虚微、濡弱或结代，心中悸动，精神委顿疲倦，形体极度虚弱羸弱，应当以滋养阴液、益气扶正，帮助正气祛除邪气为主，方用参胡三白汤、炙甘草汤、清燥养荣汤、补中益气汤。（“濡”同“软”。）
The alternation of chills and fever (Han Re Wang Lai) differs from simultaneous fever and aversion to cold (Fa Re E Han): simultaneous fever and aversion to cold occur at the same time; whereas in the alternation of chills and fever, one feels cold first, then becomes hot after the cold subsides, and feels cold again after the heat subsides. This also differs from malaria (Nue): malaria attacks have fixed times, and the duration of chills and fever are definite; this condition has no fixed attack times, and the duration of chills and fever is indefinite. Although different from malaria, the pathogenic factor resides in the half-exterior and half-interior region of the Shaoyang channel (Shaoyang Jing).
At the initial stage of disease transmission, the condition progresses from mild to severe: initially presenting as alternation of chills and fever, subsequently becoming more heat than cold, then evolving into only heat without cold, until continuous high fever throughout day and night, delirium (Chan Wang), restlessness, and excessive thirst manifest completely. After the stage of transmission, the condition recovers from severe to mild: continuous high fever gradually decreases to simple fever, sometimes stopping; further decreasing to alternation of chills and fever; further decreasing to battle sweat (Zhan Han); until the pulse becomes calm and the body cools down, leading to recovery.
Epidemic pathogens emerging from the interior to the exterior represent a mild condition, while those entering from the exterior to the interior represent a severe condition. The initial alternation of chills and fever indicates the pathogen moving from exterior to interior, invading the Shaoyang channel, where the interior righteous qi struggles against and rejects the pathogen. Subsequently, the pathogen penetrates deeply into the interior, causing both exterior and interior to generate heat, resulting in continuous high fever with an increasingly severe trend. The alternation of chills and fever after the transmission stage indicates that the pathogenic factor is declining and the righteous qi is recovering, with the pathogen moving from interior to exterior, passing through the Shaoyang channel. Previously, during continuous high fever, the pathogenic factor held dominance; now, as the righteous qi gradually harmonizes, the chills and fever occur at regular intervals. Previously, when pathogenic yang was exclusively flourishing and extreme without yin, manifesting as pure heat; now, as yin qi recovers, chills and fever contend with each other. Previously, when pathogenic factors combined in both exterior and interior, causing daily worsening of heat and thirst; now, as interior righteous qi drives out the exterior pathogen, battle sweat occurs.
For treatment before transmission, when the pathogen tends to move from exterior to interior, the primary method is to penetrate and guide out the pathogen to facilitate its transformation and resolution, using Da Yuan Yin (Reach the Origin Decoction). After transmission, when the pathogen tends to move from interior to exterior, the primary method is harmonization, using Xiao Chai Hu Tang (Minor Bupleurum Decoction). After repeated treatments with sweating and purging methods, if the pulse is deficient and faint, soft and weak, or knotted and intermittent; if there is palpitation; if mental spirit is lethargic and fatigued; if the physical form is excessively emaciated and weak, the primary method should be nourishing yin and replenishing qi, assisting the righteous qi to expel the pathogen, using Shen Hu San Bai Tang (Ginseng and Bupleurum Three Whites Decoction), Zhi Gan Cao Tang (Honey-Fried Licorice Decoction), Qing Zao Yang Rong Tang (Clear Dryness and Nourish Nutrient Decoction), and Bu Zhong Yi Qi Tang (Tonify the Middle and Augment the Qi Decoction). ("Ru" is synonymous with "Ruan".)