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Hong Kong Foot disease is generally caused by an excess of cold-dampness. Therefore, in the *Neijing* (Classic of Internal Medicine), when discussing the excess of Taiyin (Taiyin Excess), it mentions swelling of the lower legs and shins; when discussing the excess of Taiyang (Taiyang Excess), it mentions traction to the inner thigh with stiffness and rigidity of muscles and tendons. It also states that if the Earth Qi is excessive in a given year, severe cases may present with muscle atrophy, flaccidity and weakness of the feet unable to support weight, frequent spasms during walking, pain under the feet, bloating in the middle jiao after drinking, and edema of the four limbs. These are all formed by cold-damp qi. However, diseases in the world often have similar appearances but different natures, or different origins but identical manifestations. If medication is administered incorrectly, the benefits and harms will be reversed.

For instance, Hong Kong Foot disease originates from cold-damp excess, but it may progress to Lung Heat, or the pathology may arise from heat in the Stomach and foot, with wind generated in the foot. These conditions resemble Hong Kong Foot but differ significantly in their heat manifestations; they must be distinguished clearly. If heat causes foot pain, this relates to the pathway of the Lung Meridian. Thus, the *Neijing* states that if Metal Qi is excessive in a given year, the thighs, hips, and feet will all suffer. If Stomach heat causes foot disease, it is due to dysfunction of the Zongjin (Tendinous Convergence), which transmits into Wei Jue (Flaccidity and Cold Reversal).

Currently, there is a patient suffering from foot pain presenting with signs of cold-dampness from water and soil. The six pulses are deep, hidden, and active. The upper pulses are turbid while the lower pulses are deficient. The pulse at Chize (LU-5) is slightly fine and choppy. It is appropriate to warm the lower part using the following prescription:

Achyranthes Bidentatae Radix (Niu Xi, 1.5g)
Astragali Radix (Huangqi, 1.5g)
Angelicae Pubescentis Radix (Duhuo)
Angelicae Sinensis Radix (Danggui)
Ephedrae Herba (Mahuang, processed)
Ligustici Chuanxiong Rhizoma (Daxiong)
Dipsaci Radix (Xuduan)
Asari Radix et Rhizoma (Xixin)
(each 3.75g)

Grind the above into powder. Use Coicis Semen (Yiyiren) starch boiled into a thin paste to form pills the size of white mustard seeds. Take 50–70 pills on an empty stomach, washed down with warm wine or salted water.

If Lung heat leads to foot disease, the left hand pulse is entirely weak and fine, and the left Chi pulse is small, beating forcefully yet deeply. The right hand pulse is predominant, possessing "bone strength," being surging and large, with the Lung pulse being particularly pronounced; further investigation is required. If the pulse is deficient, wiry, and long, use Cui Shi's Perilla Formula (Cuishi Zisu Fang). Many people use Cui Shi's formula to treat Hong Kong Foot with success, unaware that this formula is only suitable for treating foot pain caused by Lung heat.

Perillae Fructus (Zisuzi)
Paeoniae Radix Alba (Shaoyao)
Cinnamomi Ramulus (Guangui)
Coprosmae Fructus (Yinyu)
Poria (Fuling)
Arecae Pericarpium (Dafupi)
Platycodonis Radix (Jiegeng)
Glycyrrhizae Radix et Rhizoma (Gancao, honey-fried)
(each 0.25g)
Ephedrae Herba (Mahuang, nodes removed, 3g)
Astragali Radix (Huangqi, 1.5g)

Grind the above into a coarse powder. Decoct with one slice of fresh ginger, taking approximately 9g of the mixture as a drink.

If Stomach heat causes the Zongjin to lose moisture, the feet become weak and powerless, sore and soft, sometimes with slight swelling. Diagnosing the pulse, the Stomach pulse is wiry and long upon one finger, slightly rapid, and the six pulses are generally larger. It is appropriate to use the following prescription:

Arecae Pericarpium (Dafupi, 1.5g)
Coprosmae Fructus (Yinyu, 2.25g)
Pruni Armeniacae Semens (Xingren, tip removed)
Poria (Fuling)
Coicis Semen (Yiyiren)
each 0.25g)
Citri Reticulatae Pericarpium Viride (Qingju pi, 1.5g)
Ligustici Chuanxiong Rhizoma (Chuanxiong, 3.75g)

Grind the above into a coarse powder. Decoct with ginger water at any time. Continue administering the previously mentioned Kidney-warming and Yuan-qi-strengthening medicines concurrently. If taking this medicine results in slight bowel movement, stop this medicine and administer tonifying medicines for two to three days. Once the condition stabilizes, resume this medicine.