《医学发明》云∶昔有人体充肥，香港脚始发，头面浑身支节微肿，皆赤色，足胫赤肿，
痛不可忍，不敢扶策，手近皮肤，其痛转甚，坐而复卧，卧而复起，昼夜苦楚，难以名状。
乃北土高寒，故多饮酒，积久伤脾，不能运化，饮食下流之所致。投以当归拈痛汤一两二钱，
其痛减半，再服肿痛悉除。止有右手指微赤肿，以三棱针刺手爪甲端，多出黑血，赤肿全去。
不数日因食湿面，肢体觉痛，宜服此药。
枳实（半钱） 大黄（酒煨，三钱） 羌活（一钱半） 当归身（一钱）
上 咀，作一服，水一盏半，煎至一盏，去滓，空心温服，利下两行痛止。
夫香港脚之疾，皆水湿之为也，面滋其湿，又添肢节烦疼。《内经》云∶风能胜湿，羌活
辛温，透关节去湿，故以为主；血流不行则痛，当归之辛温，散壅止痛，枳实之苦寒，治痞
消食，故以为臣；大黄苦寒，以导面之湿热，治诸血留结，取其骏快，故以为使也。
治香港脚。
仆丁酉岁在临安，约婺女亲戚吴宽夫泛湖，是时剧暑，见其用火踏上，置一布囊烘足。
叩其所以，答云∶某旧有香港脚之疾，近得一方，用川椒二三斤，实于疏布囊中，置火踏上，
跣足踏椒囊。盖椒气性热，辟去寒湿气，言甚有理，用之月余，亦渐见效。庚子岁在淳安，
宽夫经过，因问其疾，云愈之已久，乃椒囊之力也。不特某用之效，传之数亲知，皆无恙矣
，真奇方也。壬寅再来临安，适于宾次中，邂逅王成之，时为都司，见其用火踏，亦有一布
囊，问之，岂非椒乎？云又添破开槟榔并熟艾各三之一，且云∶果是奇妙。大抵足膝之病，
居下属阴，又加寒湿，阴益甚矣。血气微冷凝结，非至热不可除，今用川椒，椒性热，复加
以火蒸之，自然寒湿去矣，信乎处方之效也。
The *Medical Inventions* (Yixue Faming) records: In the past, there was a person who was obese. When his Hongjiaojiao (a disease characterized by swelling and pain in the feet/legs) first manifested, his head, face, and entire body joints were slightly swollen and red; his calves were red and swollen. The pain was unbearable, making it impossible to lean on a cane for support. Touching the skin exacerbated the pain. He would sit, then lie down, then rise again, suffering day and night in indescribable agony. This occurred because the northern regions are high and cold, leading people to drink alcohol frequently. Over time, this damaged the Spleen, impairing its transportation and transformation functions, causing dietary dampness to flow downward. Administered Danggui Niangong Tang (Angelica Sinensis Decoction for Relieving Pain), one liang two qian, the pain decreased by half. After taking it again, the swelling and pain completely disappeared. Only the right finger remained slightly red and swollen. Pricking the tip of the fingernail with a Sanleng needle (Three-edged needle) released a significant amount of dark blood, and the redness and swelling vanished entirely. A few days later, after eating wet noodles, he felt pain in his limbs and should take this medicine.
Zhishi (Immature Bitter Orange Fruit, half qian) Dahuang (Rhubarb Root, stir-baked with wine, three qian) Qianghuo (Notopterygium Rhizome, one qian half) Dangguishen (Radix Angelicae Sinensis, one qian)
Crush the above herbs into pieces. Prepare as one dose. Add one and a half lamps of water, decoct until one lamp remains. Strain the dregs. Take warm on an empty stomach. After defecating twice, the pain stops.
The disease of Hongjiaojiao is caused by water-dampness pathogenic factors. Facial dampness exacerbates joint pain. The *Neijing* states: "Wind can overcome dampness." Qianghuo is acrid and warm, penetrating the joints to dispel dampness, thus serving as the chief herb. Stagnant blood flow causes pain. Danggui is acrid and warm, dispersing stagnation and relieving pain. Zhishi is bitter and cold, treating fullness and digesting food accumulation, thus serving as the deputy herb. Dahuang is bitter and cold, guiding away the damp-heat from noodles and treating various blood stasis and clots. Its swift and potent action makes it the envoy herb.
Treating Hongjiaojiao.
In the Dingyou year, while residing in Lin'an, I went boating on the lake with my relative Wu Kuanfu from Wuzhou. At that time, it was extremely hot. I saw him using a heated foot treadle with a cloth bag placed on it to roast his feet. Upon asking the reason, he replied: "I have a chronic history of Hongjiaojiao. Recently, I obtained a prescription using two or three jin of Chuanjiao (Sichuan Pepper). I put them into a loose-weave cloth bag, placed it on the heated foot treadle, and trod upon the pepper bag with bare feet. The aroma of pepper is hot-natured and can repel cold-dampness. His reasoning was sound. After using it for over a month, I gradually saw results." In the Gengzi year, while in Chun'an, Wu Kuanfu passed by. I asked about his condition, and he said he had been cured for a long time, attributing it to the power of the pepper bag. Not only did it work for him, but when shared with several relatives and acquaintances, they too recovered without issue. It is truly a miraculous formula. In the Renyin year, returning to Lin'an, I coincidentally met Wang Chengzhi at a guesthouse. He was serving as a Dusisi (military officer) and also used a heated foot treadle with a cloth bag. When I asked if it contained pepper, he confirmed it, adding that he had included broken Binglang (Areca Seed) and Shuai Ai (Prepared Mugwort Leaf), each constituting one-third of the mixture. He remarked, "It is indeed wonderful." Generally, diseases of the feet and knees reside in the lower part of the body, which belongs to Yin. Adding cold-dampness further intensifies the Yin pathogen. Slight cold coagulation and stagnation of Qi and Blood cannot be dispelled except by extreme heat. Now, using Chuanjiao, whose nature is hot, combined with steam heating, naturally dispels cold-dampness. This confirms the efficacy of the prescription.