伤寒病后，失于调理，余邪未尽，阴阳错攻，当汗反下，当下反汗，以致为逆，邪不能解，故为百脉一宗，
举皆受病，无复经络传次，所以欲食不食，欲卧不卧，欲行不行，似寒无寒，似热无热，默默不知，口苦
便赤，药入口即吐利愈剧，如有邪祟，其脉微数，此为百合病，故用百合等汤。若溺时头痛，六十日愈。
溺时头不痛，淅然寒者，四十日愈。若溺快然而头眩者二十日愈。
伤寒邪未尽，又感风寒暑湿燥火，而成坏病，或汗吐下温针仍不解或小柴胡证罢而热尚在，亦为
坏病。盖病已过经，热留脏腑，阴阳坏乱，日久不痊，气血渐衰，变为此症。视其何逆，以法治之。
劳、为劳动之劳，复、为再病之复也。盖因伤寒新瘥，血气未平，余热未净，劳动其热，热气还经，遂复热
也。非止强力摇体，持重远行，至于梳头洗面，夏悲思虑，皆能复也。？其过用者乎。其饮食复者，乃曰
多食，过食内滞则复，余邪因食滞而复聚也。又曰、食谷则危，饮酒则剧。经曰、伤寒瘥后更发热者，小
柴胡汤和之。脉浮数者，以汗解之。脉沈实者，以下解之。然伤寒之邪，自外入也。劳复之邪，自内发也。
呜呼，食复也，劳复也，诸复可治，而御内则死矣。
昔顾子献不以华尃之诊为信，临死致有舌出数寸之验。由此观之，可不骇哉。
伤寒病痊愈后，因缺乏调理，残余的病邪尚未清除，导致阴阳失调。本应发汗解表却误用攻下法，本应攻下里实却误用发汗法，从而造成逆证，病邪无法解除。因为人体百脉同出一源（指全身经络血脉同源），所以全身都受到病邪侵害，不再遵循六经传变的次序。因此出现想吃饭却吃不下，想睡觉却睡不着，想行走却走不动，似有寒象却无寒，似有热象却无热的症状；患者沉默寡言、神情恍惚，口苦，小便色赤；药物入口即引发呕吐或腹泻，且病情加剧，仿佛被邪祟附体一般。其脉象微数，这称为百合病（一种以精神恍惚不定为主要表现的疾病），因此使用百合等方剂治疗。若排尿时头痛，六十日可愈；排尿时头不痛，但感到阵阵恶寒的，四十日可愈；若排尿顺畅但头晕目眩的，二十日可愈。
伤寒病邪未尽，又感受风、寒、暑、湿、燥、火六淫之邪，从而形成坏病（指误治或病情复杂化后的危重病症）；或者经过发汗、催吐、攻下、温针等治疗后仍不缓解，或者是小柴胡汤证已消失但余热仍在，也都属于坏病。这是因为病邪已经过了经络阶段，热邪留滞于脏腑，导致阴阳紊乱，日久不愈，气血逐渐衰弱，从而演变成这种病症。应当观察其具体的误治情况，根据相应的法则进行治疗。
“劳”指劳动，“复”指再次发病。大概是因为伤寒刚刚痊愈，气血尚未平复，余热未清，因劳累而激发余热，热气重新传入经脉，于是再次发热。不仅仅是强力活动身体、负重远行会导致复发，即使是梳头洗脸、夏季悲伤思虑，都能导致复发。难道这是过度使用体力吗？因饮食不当导致的复发，叫做多食，进食过多导致内部停滞，余邪便因食物停滞而重新聚集。又说：进食谷物则病情危急，饮酒则病情剧烈。医经记载：伤寒痊愈后再次发热的，用小柴胡汤调和；脉象浮数的，用发汗法解除；脉象沉实的，用攻下法解除。然而，伤寒的病邪是从外部侵入的；而劳复的病邪是从内部产生的。唉，饮食复和劳复都是可治的，但如果房事不节（御内）导致的复发，则是死症。
After the recovery from a cold damage disease, if proper care is neglected and residual pathogenic factors remain unresolved, yin and yang become disordered. If sweating should have been induced but purgation was mistakenly used, or if purgation should have been applied but sweating was mistakenly induced, this leads to adverse conditions where pathogens cannot be resolved. Since all vessels originate from one source (referring to the common origin of all meridians and blood vessels in the body), the entire body becomes affected by the pathogen, without following the sequential transmission of the six meridians. Consequently, there are symptoms such as wanting to eat but being unable to, wanting to sleep but being unable to, wanting to walk but being unable to, appearing cold yet not actually cold, appearing hot yet not actually hot; the patient remains silent and bewildered, with a bitter taste in the mouth and dark urine; any medicine taken induces vomiting or diarrhea, worsening the condition, as if possessed by evil spirits. The pulse is faint and rapid. This is called Baihe Bing (Lily Disease, a condition characterized primarily by mental restlessness and uncertainty). Therefore, decoctions containing Baihe (Lily Bulb) etc. are used. If headache occurs during urination, recovery takes sixty days. If there is no headache during urination but a sensation of chilliness, recovery takes forty days. If urination is smooth but accompanied by dizziness, recovery takes twenty days.
If residual pathogens from cold damage remain and are further exposed to wind, cold, summerheat, dampness, dryness, or fire, a Huai Bing (Ruined Disease, referring to critical conditions resulting from misdiagnosis/mistreatment or complex progression) forms. Alternatively, if treatment with sweating, emesis, purgation, or warm needle therapy fails to resolve the condition, or if the Xiao Chaihu Tang syndrome has ceased but residual heat persists, these also constitute Huai Bing. This is because the pathogen has passed beyond the meridian stage, with heat lingering in the zang-fu organs, causing chaos in yin and yang. After prolonged illness without recovery, qi and blood gradually decline, leading to this syndrome. One must observe the specific nature of the adverse changes and treat according to the appropriate principles.
"Lao" refers to labor/effort, and "Fu" refers to recurrence of illness. Generally, after a new recovery from cold damage, when qi and blood are not yet stabilized and residual heat remains uncleaned, physical exertion stirs up the residual heat, which returns to the meridians, causing fever to recur. This is not limited to strenuous body movement or carrying heavy loads over long distances; even combing hair, washing face, or summer-time sorrowful thinking can cause recurrence. Is it due to overexertion? Recurrence due to diet is termed "overeating"; excessive intake causes internal stagnation, allowing residual pathogens to re-aggregate due to food retention. It is said that eating grains leads to critical danger, while drinking alcohol exacerbates the severity. The classics state: For fever recurring after cold damage recovery, use Xiao Chaihu Tang to harmonize; for floating and rapid pulses, resolve via sweating; for deep and excess pulses, resolve via purgation. However, the pathogen of cold damage enters from the exterior, whereas the pathogen of Lao Fu arises from within. Alas, dietary recurrence and labor recurrence are treatable, but recurrence due to sexual indiscretion (Yu Nei) leads to death.
In the past, Gu Zixian did not trust Hua Tuo's diagnosis and indeed suffered the verification of his tongue protruding several inches upon death. From this, one can see how alarming this is.