Wei Qi (Defensive Qi) is that which warms the flesh, fills the skin, thickens the interstices (Cou Li), and governs the opening and closing of the pores. Therefore, when Wind Evil invades the Wei level, it inevitably causes aversion to wind. Aversion to wind and aversion to cold are both exterior syndromes, but aversion to wind is milder than aversion to cold. "Aversion to cold" refers to feeling chilly spontaneously even when not exposed to wind; "aversion to wind" refers to feeling no fear within a sealed room or behind curtains, but shivering with fear when exposed to wind or fanning oneself. Aversion to cold has distinctions between Yin and Yang syndromes, whereas aversion to wind belongs exclusively to Yang syndromes. Thus, there is no aversion to wind in the Three Yin diseases.

Although aversion to wind occurs in exterior syndromes, its treatment for dispersing differs: if there is no sweating and aversion to wind, it is Cold Damage (Shang Han), requiring diaphoresis, so Ma Huang Tang (Ephedra Decoction) is used; if there is sweating and aversion to wind, it is Wind Strike (Zhong Feng), requiring muscle-relieving resolution, so Gui Zhi Tang (Cinnamon Twig Decoction) is used. Even if interior syndromes are present, as long as aversion to wind has not ceased, the exterior must be resolved first. Fever with aversion to wind indicates exterior deficiency and belongs to Taiyang Disease (see "Fever · Taiyang Disease" section). After sweating, if leakage of sweat continues unceasingly, the syndrome resembles Bi Syndrome due to Wind-Dampness, presenting with back aversion to wind, sweating, difficulty in urination, and stiffness in the four limbs making flexion and extension difficult; however, if there is no fullness below the heart and no body pain, Gui Zhi Jia Fu Zi Tang (Cinnamon Twig Decoction plus Aconite) should be used (see "Spontaneous Sweating"). If it is Bi Syndrome due to Wind-Dampness, there will be painful and pulling pain in the bone joints, treated with Gan Cao Fu Zi Tang (Licorice and Aconite Decoction) (formula see "Body Pain"). For body heat, aversion to wind, neck stiffness, hypochondriac fullness, warm hands and feet, and thirst, Xiao Chai Hu Tang (Minor Bupleurum Decoction) is used (see "Hypochondriac Pain").

Headache caused by Cold Damage, although belonging to the Three Yang meridians, is most common in the Taiyang meridian. This is because Taiyang disease belongs to the exterior, and headache serves specifically as a sign of an exterior syndrome. Although there are cases of Cold Damage lasting six or seven days with headache, constipation, and heat, where Cheng Qi Tang (Order the Qi Decoction) is administered to purge, it is stated that "if the urine is clear, one knows the heat is not in the interior but remains in the exterior." From this, it is known that headache belongs to the exterior clearly. The meridians of the Taiyin and Shaoyin ascend from the foot to the chest and return without going up to the head; therefore, diseases of these two meridians do not involve headache. Only the Jueyin meridian follows the throat posteriorly, connects to the eye system, and meets the Du Meridian at the vertex, thus also involving headache. The Wu Zhu Yu Tang (Evodia Decoction) syndrome characterized by dry vomiting and spitting of saliva lacks fever, differing from Yang syndromes. However, in Wind-Warmth disease located in Shaoyin and Damp-Warmth disease located in Taiyin, headache appears conversely; such cases cannot be rigidly bound by the aforementioned rules. Headaches caused by internal factors occur intermittently, while those caused by external factors are constant until the pathogen transmits to the interior.

Fever, headache, and aversion to wind belong to Taiyang (formula theory see "Taiyang Fever"). If bowel movements are difficult, and after six or seven days there is headache, body heat, and red urine, Cheng Qi Tang is suitable; if urination is free, the disease is not in the interior but remains in the exterior, requiring diaphoresis; if there is headache, epistaxis will likely occur, and Gui Zhi Tang is suitable (theory see "Stomach Excess"). After taking Gui Zhi Tang or undergoing purgation, if head and neck stiffness, mild fever, slight fullness and pain below the heart, and difficulty in urination persist, Gui Zhi Qu Gui Jia Fu Ling Bai Zhu Tang (Cinnamon Twig Decoction minus Cinnamon plus Poria and Atractylodes Macrocephala Decoction) is used (formula theory see "Neck Stiffness"). In Taiyang Wind Strike with diarrhea and vomiting/retching, once the exterior is resolved, attack can proceed. If the patient has intermittent sweating, headache, hard fullness below the heart radiating to the hypochondrium, dry vomiting, shortness of breath, sweating without aversion to cold, this indicates the exterior is resolved but the interior is not harmonized; Shi Zao Tang (Ten Jujubes Decoction) is used (formula theory see "Hypochondriac Fullness and Pain").

It is asked: Both Shi Zao Tang and Gui Zhi Qu Gui Jia Fu Ling Bai Zhu Tang belong to patients with fluid retention (Yin Jia) and both present with head and neck stiffness. Why? This is due to meridian connections, not coincidence. The *Needle Classic* states: The Taiyang Bladder meridian originates from the inner canthus, goes up to the forehead and crosses the vertex; its branch goes from the vertex to the supra-auricular angle; the straight branch enters the brain from the vertex, emerges at the lower nape, runs along the shoulder blades, parallel to the spine to the middle of the waist, enters the muscles, connects to the Kidney, and belongs to the Bladder. The "connecting to the Kidney" mentioned above refers to the San Jiao (Triple Burner). The San Jiao is the father of Yang Qi, the official of drainage, guiding Yin and Yang, opening blockages, allowing water pathways to emerge and transform Qi. Since the Taiyang meridian has abundant blood but scarce Qi, upon disease, Qi becomes weaker. At this time, with exterior pathology and mild interior heat causing slight thirst, excessive drinking of fluids occurs. Due to weak Qi failing to transform the excess fluid, it stagnates internally, causing stagnation of blood and Qi in the primary meridian, resulting in headache and neck stiffness. If the retained fluid circulates and the meridians are unblocked, the headache heals itself.

In Warmth disease, if there is fever, headache, and a sinking pulse, and if it does not improve with body pain, the interior should be rescued using Si Ni Tang (Frigid Extremities Decoction) (theory see "Fever"). In Taiyang disease, headache may heal spontaneously after seven days because the meridian cycle is completed. If transmission to another meridian is anticipated, needling the Foot-Yangming meridian prevents transmission and leads to recovery. (Cold Damage transmits through the Three Yang and Three Yin meridians over six days; by the seventh day, it should heal. The Classic says: On the seventh day, Taiyang disease declines, and headache lessens. If it does not heal by the seventh day, Taiyang evil transmits to Yangming. Needling Foot-Yangming uses the "meet and drain" method to prevent transmission.) For floating pulse and headache belonging to Taiyang, Wan Gu (SI4) and Jing Gu (BL64) should be needled. It is also said: For exterior syndrome headache with aversion to cold and fever, He Gu (LI4) should be needled.

For Yangming disease with body heat, headache, rinsing the mouth without desire to swallow, leading to epistaxis, and rapid pulse, Xi Jiao Di Huang Tang (Rhinoceros Horn and Rehmannia Decoction) and Mao Hua Tang (Mao Hua Decoction) are used (see "Epistaxis"). For Yangming disease with severe interior and exterior heat, irritability, thirst with desire to drink, and headache like bursting, Zhu Ye Shi Gao Tang (Bamboo Leaf and Gypsum Decoction) is suitable. For Yangming headache without aversion to cold but with aversion to heat and solid stool, Tiao Wei Cheng Qi Tang (Regulate the Weight Order the Qi Decoction) is used. For Yangming disease with paradoxical absence of sweating but free urination, vomiting and coughing after two or three days, and cold extremities, severe headache must occur; if there is no vomiting/coughing and extremities are not cold, there is no headache. (*Inner Classic*: Juyang receives evil, Shaoyin is interior; getting heat causes upward reversal. Taiyang and Shaoyin are paired; this case implies Taiyang has not fully resolved. Another classic says: Yangming involves panting and aversion to people. Free urination indicates cold evil attacking internally; cold extremities and headache indicate cold evil attacking externally.)

Wu states: For Yangming headache with frontal eye pain and nasal dryness, long pulse, and no sweating, Ge Gen plus Cong Bai (Scallion White) and Bai Zhi (Angelica Dahurica) induces sweating; if sweating exists and previous sweating failed to resolve headache, Ge Gen Cong Bai Tang is used; if there is no aversion to wind but aversion to heat, spontaneous sweating, irritability, thirst, rapid and large pulse, and headache with drinking, Bai Hu Jia Bai Zhi Tang (White Tiger plus Angelica Dahurica Decoction) is used; if there are dry feces internally, steaming fever, and headache, Tiao Wei Cheng Qi Tang is used. Generally, for Yangming headache without sweating, use Ge Gen, Ma Huang, Cong Bai, Bai Zhi, Shi Gao; with sweating, use Bai Zhi, Shi Gao, Ge Gen, Chuan Xiong Tang.

For Cold Damage with wiry-thin pulse, headache, and fever, it belongs to Shaoyang; diaphoresis is contraindicated as it causes delirium. This relates to the Stomach; if the Stomach harmonizes, it heals; if not, irritability and palpitations occur. Xiao Chai Hu Tang is suitable (theory see "Bitter Taste"). Wu states: For Shaoyang meridian headache with pain at the temple or ear, wiry-rapid pulse, bitter taste, fever, and alternating chills and fever, Xiao Chai Hu Tang is used for harmonization; adding Chuan Xiong is excellent as it is a Gallbladder meridian herb. Generally, for Shaoyang headache regardless of sweating, Chai Hu Tang is used. For intermittent headache with chills/fever and tight, small pulse, phlegm in the upper diaphragm is indicated, treated with Gua Di San (Melon Seed Powder) to induce vomiting.

For headache with dry vomiting and spitting saliva, Wu Zhu Yu Tang is used. *Li Ren Shu* states: Jueyin headache indicates impending recovery, treated with Xiao Jian Zhong Tang. If sweating has occurred or not, and headache is severe, Lian Xu Cong Bai Tang (Scallion White with Roots Decoction) is used.

Lian Xu Cong Bai Tang Formula: Scallion White (with roots, cut, half sheng), Ginger (two liang). Boil in two sheng of water to obtain one sheng, divide into two doses, take warm. If ineffective, use the following formula.

Ge Gen Cong Bai Tang Formula: Ge Gen, Shao Yao, Zhi Mu (each half liang), Chuan Xiong, Cong Bai, Sheng Jiang (each one liang). Boil in three sheng of water to obtain one sheng, take hot. For intermittent headache, chest fullness, chills/fever, and tight/small pulse indicating phlegm in the diaphragm, use one qian of Gua Di Mo mixed with warm water to induce vomiting of phlegm for immediate relief.

Yun Qi Zi states: For headache and vertigo after sweating and purgation in Cold Damage, Du Huo Tang is suitable. Fang Feng, Du Huo, Xuan Fu Hua, Dang Gui (each seven qian). Chew, decoct with ginger water.

For persistent headache after febrile Cold Damage, Shi Gao Chuan Xiong Tang is used. Shi Gao, Chuan Xiong (each one liang). Chew, take five qian per dose, decoct in water.

Hai Zang states: Taiyang headache with sweating uses Gui Zhi Tang; without sweating, Ma Huang Tang. Yangming headache uses Bai Hu Tang. Shaoyang headache uses Xiao Chai Hu Tang. Taiyin headache: floating pulse uses Gui Zhi Tang; sinking pulse uses Li Zhong Tang, both added with Chuan Xiong and Xi Xin. Shaoyin headache uses Xiao Chai Hu Tang and Ma Huang Fu Zi Xi Xin Tang. Jueyin headache due to external injury to the primary meridian uses Gui Zhi Ma Huang Ge Ban Tang. Vomiting with slight bitter water expulsion uses Wu Zhu Yu Tang.

Li Dong Yuan states: Taiyin headache necessarily involves phlegm; Shaoyin headache involves cold feet and rebellious Qi. Although Taiyin and Shaoyin meridians do not reach the head, phlegm and rebellious Qi obstructing the diaphragm prevent Qi from descending smoothly to the head, causing pain.

Yun Qi Zi states: For floating pulse and headache affecting Hand-Foot Taiyang, needle Wan Gu and Jing Gu. For floating-long pulse affecting Hand-Foot Yangming, needle He Gu and Chong Yang. For floating-wiry pulse affecting Hand-Foot Shaoyang, needle Yang Chi, Qiu Xu, Feng Fu, Feng Chi. These are methods for needling headache.

*Ji Yan Fang* states: For Cold Damage headache, needle Zan Zhu.