伤寒脉弦细。头痛发热者。属少阳。少阳不可发汗。发汗则谵语。此属胃。胃和则愈。胃不
和则烦而悸。
经曰、少阳之至。其脉弦。故头痛发热者。三阳表证所同。而脉弦细。则少阳所独也。少阳经
兼半里。热气
已动。是以不可发汗。发汗则津液外亡。胃中干燥。必发谵语。云此属胃者。谓少阳邪气并于阳明
胃府也。若邪去而胃和则愈。设不和。则木中之火。又将并入心脏。而为烦为悸矣。
少阳中风。两耳无所闻。目赤。胸中满而烦者。不可吐下。吐下则悸而惊。
此少阳自中风邪之证。不从太阳传来者也。少阳之脉。起于目锐 。其支从耳后入耳中。以下
胸中。少阳受邪。壅热于经。故耳聋目赤。胸中满而烦也。是不在表。故不可吐。复不在里。故不可
下。吐则伤阳。阳虚而气弱则悸。下则伤阴。阴虚而火动则惊。
伤寒六七日。无大热。其人躁烦者。此为阳去入阴故也。
邪气在表则发热。入里则躁烦。伤寒六七日。外无大热。而其人躁烦者。邪气去阳而之阴也。
去、又训作往。言阳邪往入阴中也。
伤寒三日。三阳为尽。三阴当受邪。其人反能食而不呕。此谓三阴不受邪也。
伤寒一日太阳。二日阳明。三日少阳。四日当传太阴。内经伤寒传变之常法然也。阳邪传阴。
则当呕而不能食。若其人反能食。不呕。则邪气不传于阴。将从阳而解也。
伤寒三日。少阳脉小者。欲已也。
伤寒三日。少阳受邪。而其脉反小者。邪气已衰。其病欲解而愈。经云、大则病进。小则病退
。此之谓也。少阳病欲解时。从寅至辰上。
少阳、胆木也。从寅至辰。为木旺之时。故其病欲解。必于是三时。亦犹太阳之解于巳午未。阳
明之解于申酉戌也。
伤寒病见脉象弦细，伴有头痛、发热的症状，属于少阳病。少阳病禁止使用发汗法治疗。如果误用发汗法，会导致患者出现谵语（神志不清，胡言乱语），这是因为邪气传入胃腑。若胃气调和则病愈；若胃气不和，则会出现心烦和心悸的症状。
《内经》说：少阳经的脉象表现为弦脉。因此，头痛发热是三阳经表证共同具有的症状，但脉象弦细则是少阳病所独有的特征。少阳经兼涉半表半里，体内热气已经萌动，所以不可发汗。发汗会导致津液外泄耗损，胃中干燥，必然引发谵语。文中说“此属胃”，意思是少阳的邪气并入了阳明胃腑。如果邪气去除且胃气调和，疾病就会痊愈；假如胃气不和，那么肝胆中的火邪又将并入心脏，从而产生心烦和心悸的症状。
少阳中风，表现为两耳听不见声音，眼睛发红，胸中胀满且心烦，这种情况下禁止使用催吐或泻下法。如果误用吐法或下法，会导致心悸和惊恐。
这是少阳经直接感受风邪的证候，并非从太阳经传来。少阳经脉，起始于目外角，其分支从耳后进入耳中，下行至胸中。少阳经受邪，热邪壅滞于经络，所以导致耳聋、目赤、胸中胀满且心烦。这种病证不在表，所以不可用吐法；也不完全在里，所以不可用下法。吐法会损伤阳气，阳气虚弱、气机衰弱就会导致心悸；下法会损伤阴液，阴液亏虚、虚火妄动就会导致惊恐。
伤寒病程到了六七天，体表没有明显的大热，但病人却躁动不安、心烦意乱，这是因为邪气由阳经转入阴经的缘故。
邪气在表时表现为发热，邪气入里则表现为躁烦。伤寒六七天，体表无大热，而病人出现躁烦，说明邪气已离开阳经而进入阴经。“去”字，又解释为“往”，意指阳邪前往并进入阴分。
伤寒病程到了第三天，三阳经的病邪应当传尽，三阴经当受邪气侵袭。但如果病人反而能够进食且不呕吐，这说明三阴经没有受到邪气侵袭。
按照《内经》关于伤寒传变的常规法则：第一天病在太阳，第二天在阳明，第三天在少阳，第四天应当传入太阴。阳邪传入阴经，应当出现呕吐且不能进食的症状。如果病人反而能进食、不呕吐，说明邪气没有传入阴经，将会随着阳经之气而解除。
伤寒病程到了第三天，如果是少阳病，脉象反而变小，说明疾病将要痊愈。
伤寒第三天，少阳经受邪，但脉象反而细小，说明邪气已经衰退，疾病即将解除而痊愈。经文说：“脉大表示病势进展，脉小表示病势退却。”说的就是这个道理。
少阳病欲解之时，是从寅时到辰时这段时间。
少阳对应胆木，从寅时到辰时，是木气旺盛的时辰，所以疾病想要解除，必定是在这三个时辰。这也就像太阳病欲解于巳、午、未时，阳明病欲解于申、酉、戌时一样。
In Taiyang cold damage, if the pulse is wiry and fine, accompanied by headache and fever, it belongs to Shaoyang disease. Shaoyang disease prohibits the use of diaphoresis (sweating therapy). If diaphoresis is mistakenly applied, it will lead to delirious speech (incoherent talking due to mental confusion), which indicates the pathogen has entered the Stomach. If the Stomach Qi harmonizes, the disease will resolve; if the Stomach Qi does not harmonize, it will result in vexation and palpitations.
The Classic states: The pulse of Shaoyang is wiry. Therefore, headache and fever are common exterior syndromes of the three Yang channels, but a wiry and fine pulse is unique to Shaoyang. The Shaoyang channel involves both the half-exterior and half-interior aspects, and internal heat is already active; thus, diaphoresis is contraindicated. Diaphoresis causes body fluids to escape and be depleted, leading to dryness in the Stomach, which inevitably triggers delirious speech. When the text says "this belongs to the Stomach," it means the Shaoyang pathogen has merged with the Yangming Stomach organ. If the pathogen is eliminated and the Stomach harmonizes, the disease resolves; if it does not harmonize, the fire within the Liver and Gallbladder will merge into the Heart, causing vexation and palpitations.
In Shaoyang wind strike, symptoms include bilateral deafness, red eyes, chest fullness, and vexation. In such cases, emesis (vomiting induction) and purgation (drastic purging) are prohibited. If emesis or purgation is mistakenly applied, it leads to palpitations and fright.
This is a syndrome where Shaoyang directly contracts wind pathogens, not transmitted from the Taiyang channel. The Shaoyang meridian originates at the outer canthus of the eye; its branch enters the ear from behind the ear and descends to the chest. When Shaoyang is affected by pathogens, heat obstructs the meridians, resulting in deafness, red eyes, chest fullness, and vexation. Since the condition is not on the exterior, emesis is contraindicated; since it is not fully interior, purgation is contraindicated. Emesis damages Yang Qi; when Yang Qi is deficient and Qi becomes weak, palpitations occur. Purgation damages Yin fluids; when Yin is deficient and fire moves recklessly, fright occurs.
After six or seven days of cold damage, if there is no significant external fever but the patient is restless and vexed, this is because the pathogen has moved from the Yang channels into the Yin channels.
When the pathogen is in the exterior, fever manifests; when it enters the interior, restlessness and vexation manifest. After six or seven days of cold damage, with no major external fever but the presence of restlessness and vexation, it indicates that the pathogen has left the Yang and entered the Yin. "Qu" (departure) is also interpreted as "going," meaning the Yang pathogen goes into the Yin aspect.
On the third day of cold damage, the three Yang channels' influence should be exhausted, and the three Yin channels should receive the pathogen. However, if the patient can eat and does not vomit, it indicates that the three Yin channels have not received the pathogen.
According to the normal law of transmission in cold damage described in the Neijing: On the first day, it affects Taiyang; on the second day, Yangming; on the third day, Shaoyang; on the fourth day, it should transmit to Taiyin. When Yang pathogens transmit to Yin, vomiting and inability to eat should occur. If the patient can instead eat and does not vomit, it means the pathogen does not transmit to Yin and will likely resolve through the Yang channels.
On the third day of cold damage, if the Shaoyang pulse is small, the disease is about to resolve.
On the third day of cold damage, if Shaoyang is affected but the pulse is unexpectedly small, it indicates that the pathogen has declined, and the disease is about to resolve and heal. The Classic states: "A large pulse indicates disease progression; a small pulse indicates disease retreat." This refers to this situation.
Shaoyang disease tends to resolve between the hours of Yin and Chen.
Shaoyang corresponds to Wood of the Gallbladder. From Yin to Chen, it is the time when Wood energy is prosperous; therefore, the disease tends to resolve during these three periods. This is similar to how Taiyang disease tends to resolve during Si, Wu, and Wei hours, and Yangming disease tends to resolve during Shen, You, and Xu hours.