Si Ni San (Four Reversal Powder) is a renowned formula from the “Shang Han Lun” (Treatise on Cold Damage), composed of four herbs: Chai Hu (Bupleurum), Shao Yao (Peony), Zhi Shi (Bitter Orange), and Gan Cao (Licorice), which are ground into a powder and taken with rice soup. Its functions include soothing the liver, relieving depression, promoting qi flow, and regulating the spleen. It primarily addresses two conditions: the first is Yang depression with reversal symptoms, characterized by cold hands and feet, abdominal pain, or diarrhea with a heavy sensation, and a wiry pulse; the second is liver and spleen qi stagnation, presenting with rib distension, abdominal pain, and a wiry pulse.
This formula appears in the section on Shaoyin diseases in the “Shang Han Lun” and is one of the most challenging commonly used formulas to understand. The difficulties arise from several aspects: what does the term “Four Reversal” refer to? How does this differ from the “Four Reversal” treated by Si Ni Tang (Four Reversal Decoction)? What are the underlying pathological mechanisms? These questions have puzzled many, and previous textbooks on formulas have not provided clear explanations.
The “Four Reversal” referred to in Si Ni San primarily indicates the coldness of the limbs, specifically cold hands and feet. Most practitioners believe that its pathological mechanism falls under “Yang depression with Four Reversal,” which is quite different from the true Yang deficiency treated by Si Ni Tang. This distinction is evident from the markedly different herbal combinations in the two formulas; the pairing of Fu Zi (Aconite) and Gan Jiang (Dried Ginger) in Si Ni Tang is far removed from this formula. The Four Reversal syndrome in Si Ni Tang arises from a deficiency of Yang qi, leading to insufficient warmth and nourishment throughout the body, typically occurring in critical conditions, making its pathogenesis easier to understand. In contrast, the “Four Reversal” treated by Si Ni San is much milder and more commonly seen in “normal individuals.” Is it a disease when these individuals have slightly cold hands and feet? Can it be treated? These questions are perplexing. In reality, the “Yang depression with Four Reversal” syndrome treated by Si Ni San is closely related to its other main syndrome, “Liver Qi Stagnation and Spleen Stagnation,” and should be discussed together.
Liver Qi stagnation can lead to various pathological outcomes, one of which is the liver qi invading the spleen. The results of this invasion can vary in severity and symptom presentation. A common outcome is that the spleen is constrained, leading to spleen and stomach qi stagnation, which affects the spleen’s ability to ascend clear qi and descend turbid qi, resulting in symptoms such as dampness obstructing the spleen and stomach. Clinically, this may initially present as abdominal distension, fullness, and reduced appetite; further progression can lead to chest and rib distension, abdominal pain, loose stools, reduced appetite, or overeating, forming the syndrome of liver qi stagnation and spleen stagnation, primarily manifesting as localized symptoms. As the time of liver qi stagnation affecting the spleen increases and the condition worsens, prolonged spleen stagnation can lead to deficiency, resulting in systemic symptoms primarily characterized by qi and blood deficiency, such as dizziness, pallor, shortness of breath, and fatigue, which is termed liver qi stagnation with spleen deficiency.
In addition to the aforementioned symptoms centered around the spleen and stomach, liver qi invading the spleen can also manifest as another category of symptoms, namely abnormal sensations in the limbs. Since the spleen governs the muscles, all muscles rely on the spleen for qi, but the muscles of the limbs, especially the hands and feet, are less accessible to Yang and can easily become deficient. Therefore, when the spleen qi and liver qi are initially constrained, the spleen qi cannot normally distribute Yang qi, leading to malnourishment of the muscles and an inability to warm the limbs, resulting in mild symptoms of qi stagnation and insufficient qi and blood reaching the extremities, causing cold limbs, or even severe symptoms of qi deficiency and insufficient qi and blood reaching the extremities, leading to weakness in the limbs. Thus, it can be seen that the pathogenesis of the “Four Reversal” syndrome in Si Ni San is fundamentally due to the liver wood overcoming the spleen earth and spleen qi obstruction. This syndrome is an intermediate or transitional syndrome of liver qi stagnation and spleen deficiency.
In Si Ni San, Chai Hu and Shao Yao work together to soothe the liver and relieve depression, harmonizing the liver and spleen, and alleviating pain; Zhi Shi promotes qi flow and guides stagnation, significantly enhancing the pain-relieving effects when paired with Shao Yao; Gan Cao tonifies the spleen and harmonizes the properties of the herbs. A particular focus of this formula is its method of administration, which is to take it with rice soup. Rice soup is an excellent remedy for tonifying and supplementing the spleen. The formula does not use a large quantity of herbs to deliberately tonify the spleen, indicating that the phenomenon of spleen deficiency is not severe; taking it with rice soup is akin to taking Zhi Shi and Shao Yao San with wheat porridge, serving as a gentle and effective method to tonify the spleen and stomach.
The “Shang Han Lun” offers unique insights into this condition, emphasizing not only the phenomenon of cold limbs due to the spleen’s inability to distribute Yang qi to the extremities but also placing it alongside the critical treatment of Shaoyin diseases with Si Ni Tang, which significantly raises awareness of this condition. The “Four Reversal” syndrome treated by this formula is important not for its severity but for its prevalence. Clinically, a large population exhibits symptoms of cold hands and feet without significant other discomfort, particularly among women. This phenomenon is closely linked to the physiological and pathological characteristics of women. The liver stores blood and governs the smooth flow of qi; due to the presence of menstruation, women naturally experience a contradiction between the liver storing blood and the smooth flow of qi, hence the saying “women have more blood and less qi”. Here, “qi” refers to liver qi, and liver qi stagnation is extremely common among women, making the syndrome of liver qi obstructing the spleen widely present in common gynecological diseases.
Modern pharmacological studies indicate that this formula has a broad effect on the digestive system, exhibiting anti-inflammatory and choleretic properties, increasing bile secretion and excretion; it promotes gastric emptying and enhances intestinal peristalsis; it can improve inflammatory edema in liver cells and counteract liver damage; additionally, it has therapeutic effects on arrhythmias.
Contraindications: It should not be used in cases of Yin syndrome with extreme coldness in the elbows or knees, or in cases of cold extremities due to Yang deficiency. It is also not suitable for those with liver Yin deficiency or middle qi deficiency with cold; caution is advised.
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