A sore of gradual onset appearing on the hands and feet, and more frequently on the toes. It starts as a yellow blister the size of a millet seed. The skin is maroon like the color of boiled jujubes. It gradually putrefies and ulcerates, spreads outward, and penetrates inward to the flesh, sinew, and bone. It gives off a malign smell. On the toes, it can spread up onto the feet, or to other toes. The sore is associated with a burning pain that is usually intermittent and that usually occurs suddenly when walking or at night. It arises when as a result of rich food, lack of exercise, or excessive consumption of hot kidney-supplementing medicinals, depressed fire toxic evil brews in the bowels and viscera and disperses yīn humor. It may also arise when cold-damp evil toxin causes disharmony of provisioning and defense and stagnation of qì and blood. A sloughing flat-abscess is difficult to cure, especially if treatment is not administered early in its development.
Medicinal therapy: Depending on the cause, Mysterious Four Resting Hero Decoction (四妙勇安汤sì miào yǒng ān tāng), Harmonious Yáng Decoction (阳和汤yáng hé tāng), or Peach Kernel and Carthamus Four Agents Decoction (桃红四物汤táo hóng sì wù tāng) can be selected as the basic formula to treat fire toxin, cold-damp evil toxin, and blood stasis respectively. Add ground beetle (Eupolyphaga seu Steleophaga, 蟅虫zhè chóng), notoginseng (Notoginseng Radix, 三七sān qī), frankincense (Olibanum, 乳香rǔ xiāng), myrrh (Myrrha, 没药mò yào), salvia (Salviae Miltiorrhizae Radix, 丹参dān shēn), moutan (Moutan Cortex, 牡丹皮mǔ dān pí), lonicera stem and leaf (Lonicerae Caulis, 忍冬藤rěn dōng téng) smooth greenbrier root (Smilacis Glabrae Rhizoma, 土茯苓tǔ fú líng), and bushy knotweed (Polygoni Cuspidati Rhizoma, 虎杖hǔ zhàng) to quicken the blood and disperse stasis and to clear heat and relieve pain. For qì and blood vacuity, use Perfect Major Supplementation Decoction (十全大补汤shí quán dà bǔ tāng) or Ginseng Provisioning-Nourishing Decoction (人参养荣汤（丸）rén shēn yǎng róng tāng (wán)).
Acumoxatherapy: Base treatment mainly on LI and GB.
Point selection according to affected area: On the upper limbs, select LI-4 (Union Valley, 合谷 hé gǔ) joined to SI-3 (Back Ravine, 后溪 hòu xī), LI-11 (Pool at the Bend, 曲池 qū chí) joined to HT-3 (Lesser Sea, 少海 shào hǎi), and HT-2 (Green-Blue Spirit, 青灵 qīng líng); add LI-10 (Arm Three Lǐ, 手三里 shǒu sān lǐ) for the thumb, PC-6 (Inner Pass, 内关 nèi guān) for the middle finger, TB-5 (Outer Pass, 外关 wài guān) for the fourth finger (ring finger), and HT-5 (Connecting Lǐ, 通里 tōng lǐ) for the little finger. On the lower limbs, select GB-34 (Yáng Mound Spring, 阳陵泉 yáng líng quán) joined to SP-9 (Yīn Mound Spring, 阴陵泉 yīn líng quán), GB-39 (Suspended Bell, 悬钟 xuán zhōng) joined to SP-6 (Three Yīn Intersection, 三阴交 sān yīn jiāo), and Vessel’s Root (脉根mài gēn); add ST-36 (Leg Three Lǐ, 足三里 zú sān lǐ), and ST-40 (Bountiful Bulge, 丰隆 fēng lóng) for the back of the foot and the second and third toes; add SP-8 (Earth’s Crux, 地机 dì jī) for the great toe. Needle with drainage and add moxa.
Point selection according to cause: For depressed fire toxin, add PC-3 (Marsh at the Bend, 曲泽 qū zé), BL-40 (Bend Center, 委中 wěi zhōng), Eight Evils (八邪bā xié), and Eight Winds (八风bā fēng), needling with drainage. For cold-damp evil toxin, add CV-12 (Center Stomach Duct, 中脘 zhōng wǎn), ST-25 (Celestial Pivot, 天枢 tiān shū), LI-4 (Union Valley, 合谷 hé gǔ), SP-9 (Yīn Mound Spring, 阴陵泉 yīn líng quán); and ST-36 (Leg Three Lǐ, 足三里 zú sān lǐ), needling with drainage and adding moxa. For blood stasis, add BL-17 (Diaphragm Transport, 膈俞 gé shù), SP-10 (Sea of Blood, 血海 xuè hǎi), and LR-3 (Supreme Surge, 太冲 tài chōng), needling with even supplementation and drainage or with drainage.