产后血气虚损，阴阳不和，败血不散，能令乍寒乍热，阴胜则乍寒，阳胜则乍热，阴阳
相乘
则或寒或热。若因产劳伤脏腑，血弱不能宣越，亦令败血不散，入于肺则热，入于脾(何为
败血入肺则热，入脾则寒也?岂以肺主气，气不和而热，脾统血，血不荣而寒乎?抑脾阴肺阳
而自为寒热耶?然总以逐瘀为主，而温凉之法有不同也)则寒。若误作疟治之则谬矣。阴阳不
和者宜增损四物汤，败血不散者用夺命丹。问曰∶二者何以别之?曰∶时有刺痛者，败血也
。但寒热无他症者，阴阳不和也(用增损四物汤不一，当随病加减)。
按薛氏曰∶产后寒热，因血气虚弱或脾胃亏损，乃不足之症。经云∶阴虚则发热，阳虚
则恶
寒。若兼大便不通，尤属气血虚弱，切不可用发表降火。若寸口脉微，名阳气不足，阴气上
入于阳中则恶寒，须用补中益气汤。尺部脉弱，名阴气不足，阳气下陷于阴中则发热，用六
味地黄丸。大抵阴不足，阳往从之则阳内陷而发热；阳不足，阴往从之则阴上入而恶寒。此
阴阳不分其归，以致寒热交争，故恶寒而发热也。当用八珍汤。若病后四肢发热，或形气倦
怠，此元气未复，湿热乘之故耳。宜补中益气汤。若肌热，大渴引饮，面红目赤，此血虚发
热，用当归补血汤。
产后血气虚弱亏损，阴阳失调，恶血（指离经之血或瘀血）停滞不散，会导致忽冷忽热。阴气偏胜则出现忽冷，阳气偏胜则出现忽热，阴阳相互侵扰则时而发冷时而发热。如果因为分娩劳力损伤脏腑，血液虚弱不能宣通发散，也会导致恶血停滞。恶血进入肺脏则表现为发热，进入脾脏则表现为寒冷。（为何败血入肺则热，入脾则寒呢？难道是因为肺主气，气机不和而发热；脾统血，血不荣养而发冷吗？还是说脾阴与肺阳各自产生寒热呢？然而总的治疗原则以祛除瘀血为主，但温法和凉法有所不同。）如果误当作疟疾治疗就错了。属于阴阳不和的，适宜使用增损四物汤；属于恶血不散的，使用夺命丹。问：如何区分这两种情况？答：如果时有刺痛感，是恶血阻滞；如果只有寒热而没有其他症状，是阴阳不和（使用增损四物汤并非固定不变，应当根据病情加减）。
按薛氏（薛己）所说：产后寒热，是由于血气虚弱或者脾胃亏损，属于虚证。《内经》说：阴虚则发热，阳虚则恶寒。如果兼有大便不通，更属于气血虚弱，千万不可使用发表（解表）和降火的方法。如果寸口脉微，名为阳气不足，阴气上入于阳分则恶寒，须用补中益气汤。尺部脉弱，名为阴气不足，阳气下陷于阴分则发热，用六味地黄丸。大抵阴气不足，阳气就会随之向内陷入而发热；阳气不足，阴气就会随之向上侵入而恶寒。这是因为阴阳之气没有分清其归属，导致寒热交争，所以既恶寒又发热。应当使用八珍汤。如果在病后四肢发热，或者形体气息倦怠，这是元气尚未恢复，湿热邪气乘虚而入的缘故。适宜用补中益气汤。如果出现肌肤发热，极度口渴想喝水，面色红赤眼睛发红，这是血虚发热，用当归补血汤。
After childbirth, the deficiency and depletion of Qi and Blood, disharmony of Yin and Yang, and failure of lochial stasis (stagnant blood) to dissipate can cause alternating chills and fever. When Yin is in excess, there are sudden chills; when Yang is in excess, there are sudden fevers; when Yin and Yang contend with each other, there are intermittent chills or fevers. If organ damage occurs due to labor during childbirth, and weak Blood fails to circulate freely, it also leads to the retention of lochial stasis. If this stasis enters the Lung, fever results; if it enters the Spleen, coldness results. (Why does lochial stasis entering the Lung cause fever, while entering the Spleen causes cold? Is it because the Lung governs Qi, and Qi disharmony leads to heat, while the Spleen controls Blood, and Blood failing to nourish leads to cold? Or do Spleen Yin and Lung Yang generate cold and heat independently? However, the general treatment principle focuses on expelling stasis, though the methods of warming and cooling differ.) If mistakenly treated as malaria, it would be erroneous. For cases of Yin-Yang disharmony, Zengsun Siwu Tang (Modified Four Substances Decoction) is appropriate; for cases of retained lochial stasis, Duoming Dan (Life-Restoring Pill) should be used. Question: How to distinguish between these two? Answer: Intermittent stabbing pain indicates lochial stasis. Chills and fever without other symptoms indicate Yin-Yang disharmony (The use of Zengsun Siwu Tang is not fixed; it should be modified according to the specific condition).
According to Xue Ji: Postpartum chills and fever, caused by weakness of Qi and Blood or impairment of the Spleen and Stomach, are deficiency syndromes. The Classic states: Yin deficiency leads to fever, and Yang deficiency leads to aversion to cold. If accompanied by constipation, it particularly belongs to Qi and Blood deficiency, and one must absolutely avoid using exterior-releasing or fire-descending methods. If the Cun position (distal radial pulse) is faint, it is named Yang Qi deficiency, where Yin Qi ascends into the Yang aspect causing aversion to cold; Buzhong Yiqi Tang (Tonify the Middle and Augment the Qi Decoction) is required. If the Chi position (proximal radial pulse) is weak, it is named Yin Qi deficiency, where Yang Qi sinks into the Yin aspect causing fever; Liuwei Dihuang Wan (Six-Ingredient Rehmannia Pill) is used. Generally, when Yin is insufficient, Yang follows it inward, sinking internally and causing fever; when Yang is insufficient, Yin follows it upward, invading externally and causing aversion to cold. This is because the Yin and Yang fail to distinguish their proper locations, leading to a struggle between cold and heat, thus resulting in both aversion to cold and fever. Bazhen Tang (Eight-Treasure Decoction) should be used. If after illness there is heat in the four limbs, or fatigue in form and Qi, this is due to unrestored Yuan Qi (Original Qi) being invaded by damp-heat; Buzhong Yiqi Tang is suitable. If there is skin heat, extreme thirst with desire to drink, red face, and red eyes, this is heat due to Blood deficiency; Danggui Buxue Tang (Angelica Tonifying Blood Decoction) should be used.