The condition of metatarsus blistering refers to the appearance of dense pustules or blisters of varying sizes on the palms and metatarsus. Initially, this condition presents with a burning or itching sensation on the palms and metatarsus, followed by the emergence of pustules or blisters as small as pinpoints. Some pustules may merge into patches, with surfaces that become eroded or dry and scaly. Some blisters have thicker walls and can also merge to form larger blisters that are not easily ruptured. Both pustules and blisters can recur repeatedly. Waike Zhengzong mentions "river snail blisters," and Yizong Jinjian refers to "foot dampness qi (tinea pedis)," both of which fall within the scope of this condition.

bubble_chart Pattern Analysis

1. Dampness-heat︰Dense, needle-tip-sized blisters or pustules appear on the metatarsus, primarily blisters, which may merge into patches. After rupturing, the surface becomes moist and eroded, drying to form large flakes of peeling skin. The blisters may recur in waves. This is often caused by dampness-heat encumbering the spleen, leading to dysfunction of the spleen in transportation, resulting in water-dampness stagnating in the skin. The condition is mainly characterized by blisters, mostly localized to the palms and metatarsus, with generally no obvious systemic symptoms. The onset is slow, and the treatment involves clearing heat and draining dampness. A commonly used prescription is the Clearing Heat and Dispelling Dampness Decoction.
2. Exuberant Toxin-Heat︰The rash initially appears as flushed skin on the fingers, palms, or metatarsus, quickly developing dense pustules the size of pinpoints, which may later merge into patches. In severe cases, it can spread to other parts of the body. It is often accompanied by fever and chills, dry mouth, constipation, dark urine, and other symptoms. The tongue appears red with a yellow coating, and the pulse is surging and rapid or thin and rapid. This is mostly due to prolonged accumulation of dampness-heat turning into toxin or combined infection with external toxic pathogens, leading to stagnation of dampness toxin and its binding with heat, resulting in intense toxic heat or blazing of both qi and blood. The clinical characteristics, though both involve blisters and pustules, primarily manifest as pustules, which can spread to other parts of the body and are often accompanied by systemic discomfort such as fever and chills, with potential sudden outbreaks. Clinical treatment should focus on clearing heat and cooling blood, removing toxin, and eliminating dampness. A commonly used prescription is the removing toxin cooling blood decoction.
3. Spleen Deficiency with Dampness Retention︰Deep-seated blisters appear on the palms and soles of the feet, either clustered together or merging into large blisters. The blister walls are thick and not easily ruptured, accompanied by intense itching. The skin is generally not red, and the fluid inside the blisters is white. If the blisters rupture, they may expose an eroded base, while dried and absorbed blisters may leave scaling on the surface. Symptoms often include fatigue, abdominal distension, fullness, and loose stools. The pulse is slow, the tongue body is swollen, and the tongue coating is greasy. This condition is usually caused by dietary irregularities that impair the spleen and stomach, leading to dysfunction of the spleen in transportation, trapping dampness in the skin's striae and interstices, preventing its release. The onset is slow, with deep-seated blisters that may cluster or merge into large blisters with thick walls that are difficult to rupture. Treatment focuses on strengthening the spleen and eliminating dampness, commonly using the Strengthening the Spleen and Eliminating Dampness Decoction.
4. Dampness Toxin Erosion︰Blisters or small pustules often appear superficially on the thenar eminence of the palm or the metatarsal arch of the foot, accompanied by intense itching that worsens with heat. When ruptured, they exude fluid and gradually spread outward. Over time, the blisters or pustules dry out, forming a keratinized, scaly surface. This condition is often accompanied by maceration between the fingers or toes or fungal nail infections. It is usually caused by prolonged exposure to damp environments, getting caught in the rain, wading through water, or working in wet conditions. Therefore, it frequently occurs on the thenar eminence or the metatarsal arch, presenting as superficial small blisters that rupture easily. A commonly prescribed formula is the modified Removing Toxin and Dampness Decoction.

bubble_chart Documentation

1. Waike Zhengzong: River snail sores mostly grow on the hands and feet, suddenly like a burning fire, followed by the appearance of purple, white, and yellow blisters. This is due to the spleen channel's wind-dampness attacking and infusing, which soon gradually causes distending pain and discomfort. Use a thread needle to puncture and drain the toxic water, then cover with Taiyi ointment. If the sores reappear after being punctured, internal administration of the Removing Toxin and Purging Spleen Decoction can cure them.