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Hong Kong foot (a disease characterized mainly by redness, swelling, and pain in the lower legs) is caused entirely by damp-heat pathogenic factors. The *Classic of Internal Medicine* states: "When injured by dampness, the lower part of the body is affected first." Dampness stagnates and transforms into heat; when dampness and heat contend with each other, the disease arises. However, dampness can be acquired externally or generated internally. Although their causes differ, the manifested symptoms are consistent. The patient presents with fever and aversion to cold, sometimes accompanied by headache, resembling Taiyang syndrome (Cold Damage), but differs in that it originates with redness and swelling of the shins, tendon spasms and pulling pain, and difficulty in walking. In mild cases, the pain is confined to the feet; in severe cases, the pain spreads from the feet to the genitalia, reaches the lower abdomen, passes through the hypochondrium, and ascends to the head. In even more severe cases, it develops into Hong Kong foot rushing to the heart (damp-heat pathogenic factors attacking the Heart upwards), presenting with coma, delirium, incessant panting, and continuous vomiting, often leading to death. Treatment should primarily focus on clearing heat, removing dampness, and promoting urination. This is because Hong Kong foot is a condition of obstruction and urgency; it favors free flow and abhors blockage. Therefore, Sun Simiao stated: "Hong Kong foot patients die due to excess Qi (pathogenic excess), never due to deficiency caused by medication." Chen Shigong (courtesy name Zhongchun) discussed the treatment of Hong Kong foot, warning against the use of tonifying, warming, drying, and ascending drugs. However, one must also avoid excessive purging or the exclusive use of Qi-breaking formulas. According to the *Jin Gui Yao Lue*, for Hong Kong foot with upward invasion causing numbness in the lower abdomen, the cause is attributed to cold-dampness reversing upward and obstructing the lower abdomen. Eight-Ingredient Pill (Ba Wei Wan, i.e., Shen Qi Wan) is used to strengthen True Yang and expel cold-dampness. However, Hong Kong foot caused by cold-dampness is extremely rare; misusing warm-hot medicines will inevitably lead to disaster, so careful differentiation is essential. Ancients discussed that the root of Hong Kong foot lies in dampness. If acquired externally, such as wading in water, sudden rain, or dwelling in low, damp places, the feet are affected first; dampness stagnates and transforms into heat, causing pain upon onset. If generated internally, such as dampness from diet, including alcohol, fruits, melons, milk, and cheese, which contain both dampness and heat, it enters the Stomach first, then transports upward to the Spleen. The Spleen governs the four limbs, and water nature flows downward; thus, damp-heat transformed by the Spleen flows directly into the feet. In summary, in Hong Kong foot, swelling indicates dampness, and pain indicates heat; this is an unchangeable principle. Fang Ji Yin (Revised Edition) treats damp-heat in the feet, with redness and swelling of the shins (sometimes without redness), tendon spasms and pulling pain, fever, and aversion to cold. It is indicated for this pattern with modifications. Han Fang Ji (Tetrandrae Radix, unblocks damp-heat in the Lower Jiao, essential for resolving obstructed Hong Kong foot, praised by Qian Yi), Huang Bo (Phellodendri Cortex, treats damp-heat swelling and pain in the Lower Jiao, 2 qian), Ren Dong Hua (Lonicerae Flos, treats Hong Kong foot tendon and bone pulling pain; fresh vines, several liang, decocted in water instead of boiling yields better results), Chuan Bi Xie (Dioscoreae Hypoglaucae Rhizoma, removes turbidity and clarifies purity, 5 qian each), Mu Gua (Chaenomelis Fructus, removes dampness and relaxes tendons), Bai Fu Ling (Poria, 3 qian each), Ze Xie (Alismatis Rhizoma), Mu Tong (Akebiae Caulis, promotes urination and removes dampness, approx. 1 qian each), Shi Hu (Dendrobii Caulis), Yi Yi Ren (Coicis Semen, benefits the Spleen and removes dampness, 5 qian each). If there is redness and swelling, add Xi Jiao (Rhinocerotis Cornu); also used for chest oppression and irritability. Add further Bing Lang (Arecae Semen, directs Qi downward), Ling Yang Jiao (Saigae Tataricae Cornu, directs rebellious Qi downward and treats heat oppression). If panting and vomiting occur, add Mai Dong (Ophiopogonis Radix) and Pi Pa Ye (Eriobotryae Folium). If headache occurs, add Gan Ju (Chrysanthemi Flos). This is a formula for clearing heat, removing dampness, and promoting urination. Since Hong Kong foot is caused by damp-heat, this formula is generally suitable as the main prescription, expanded and modified according to accompanying symptoms for optimal efficacy. Jin Gui Yao Lue Fan Shi Tang treats Hong Kong foot rushing to the heart. (Damp-heat Qi rushing upward to the Heart, meaning earthy qi adding to heavenly qi.) Fan Shi (Alumina, astringes dampness, clears turbidity, and detoxifies, 4 liang). Decoct in water to soak the feet. (Prevents damp-heat from rushing upward.) Can add Ku Shen (Sophorae Flavescentis Radix, 4 qian).