Fu Zi (Aconite) is one of the four main herbs in Traditional Chinese Medicine (TCM) (Ren Shen (Ginseng), Shi Gao (Gypsum), Da Huang (Rhubarb), Fu Zi), also known as the “Four Pillars of Medicine,” highlighting its significance.The function of Fu Zi lies in warming the Yang of the five internal organs. Historically and presently, Zhang Zhongjing is the foremost practitioner known for utilizing Fu Zi. In the “Shang Han Lun” (Treatise on Cold Damage), Fu Zi is used in various formulas for the six meridian diseases, including Gui Zhi Jia Fu Zi Tang (Cinnamon Twig Decoction with Aconite), Gui Zhi Qu Shao Jia Fu Zi Tang (Cinnamon Twig Decoction minus Peony with Aconite), Gan Cao Fu Zi Tang (Licorice and Aconite Decoction), Gui Zhi Fu Zi Tang (Cinnamon Twig and Aconite Decoction), Ma Huang Xi Xin Fu Zi Tang (Ephedra and Asarum Decoction with Aconite), Ma Huang Fu Zi Gan Cao Tang (Ephedra, Aconite, and Licorice Decoction), Fu Zi Xie Xin Tang (Aconite Decoction for Heart Drainage), and Shao Yao Gan Cao Fu Zi Tang (Peony and Licorice Decoction with Aconite). In the Tai Yin chapter, there is Li Zhong Tang (Regulating the Center Decoction); in the Shao Yin chapter, there are Si Ni Tang (Frigid Extremities Decoction), Si Ni Jia Ren Shen Tang (Frigid Extremities Decoction with Ginseng), Tong Mai Si Ni Tang (Unblocking the Pulse Frigid Extremities Decoction), Tong Mai Si Ni Jia Zhu Dan Zhi Tang (Unblocking the Pulse Frigid Extremities Decoction with Pig Gallbladder), Gan Jiang Fu Zi Tang (Dried Ginger and Aconite Decoction), Fu Zi Tang (Aconite Decoction), Bai Tong Tang (White Unblocking Decoction), Bai Tong Jia Zhu Dan Zhi Tang (White Unblocking Decoction with Pig Gallbladder), Zhen Wu Tang (True Warrior Decoction), and Fu Ling Si Ni Tang (Poria Frigid Extremities Decoction). There are nearly twenty formulas, accounting for more than one-sixth of the 112 formulas in the entire book. Among the prescriptions using Fu Zi, the most important are those for heart-strengthening, such as Si Ni Tang, as few patients die from heat diseases due to heat itself, but many succumb to heart failure. In the past, Mr. Zhang Ciguang pointed out, “Zhongjing was the first to discover heart failure in heat diseases,” and the first choice for rescuing heat-induced heart failure is Fu Zi. In the 1930s, Mr. Zhu Weijun gained fame in Shanghai for his adept use of Fu Zi, earning the nickname “Zhu Fu Zi.” Even in cases of high fever, delirium, dry lips, and rapid pulse, he insisted on using Fu Zi, capturing the essence of heat diseases that consume heart energy, saving many critically ill patients. Mr. Zhang once expressed in the preface of Chen Sushe’s compilation “Shang Han Zhi Nan” that he greatly admired Zhu Weijun’s “ruthless” use of medicine. Mr. Zhang also skillfully used Fu Zi, particularly in the middle and later stages of heat diseases, where the evil force weakens but the body is exhausted, posing a risk of collapse. He used the formula from “Feng’s Golden Bag” called Quan Zhen Yi Qi Tang (Complete True Qi Decoction), which combines Ren Shen (Ginseng), Fu Zi (Aconite), Di Huang (Rehmannia), Mai Dong (Ophiopogon), to strengthen the heart, rescue the Yang, nourish Yin, and benefit Qi, which can be considered a groundbreaking approach in treating heat diseases. However, the experiences and insights of Mr. Zhu and Mr. Zhang were often dismissed by the uninformed until they began to regain prominence in the last thirty years. The use of Si Ni Tang (and its improved formulations) for treating infectious shock and cardiogenic shock has been widely applied in internal medicine, with remarkable effects in strengthening the heart, raising blood pressure, and improving microcirculation. Mr. Zhu Liangchun’s clinical experience indicates that in heat diseases, the use of Fu Zi must be discerning; if symptoms such as cold limbs, profuse cold sweat, weak pulse, and cold breath appear, it is often too late to use it. He proposed the following criteria: pale, moist, plump tongue; thirst without desire to drink, or only desiring hot soup; pale complexion; sweating with cold limbs; clear urine. Even when high fever, delirium, agitation, and rapid pulse are present, Fu Zi should still be used to invigorate the declining Yang energy and prevent the loss of Yang. Over twenty years ago, under Mr. Zhu’s guidance, I used Fu Zi in many critically ill patients, especially children with toxic dysentery and measles complicated by pneumonia. Despite high fever and rapid pulse, I did not hesitate to use it, effectively saving many lives. A few years ago, I consulted on a pneumonia patient named Zhu at Beijing Anzhen Hospital, who had a persistent high fever for eight days, was lethargic, agitated, had rapid breathing, and a pulse of 150 beats per minute, yet had a pale complexion, sweating, a pale tongue, and clear urine. I immediately used Hong Ren Shen (Red Ginseng), Fu Pian (Aconite slices), Long Gu (Dragon Bone), Duan Mu Li (Calcined Oyster Shell), Bai Shao (White Peony), Zhi Gan Cao (Honey-fried Licorice), Su Zi (Perilla Seed), Ting Li Zi (Descurainia Seed), Zhi Qiao (Bitter Orange), and Jie Geng (Platycodon). The department head questioned the prescription, saying, “Ginseng is a great tonic, and Fu Zi is very warming. The child has a temperature above 39 degrees; according to your TCM theory, the evil heat is rampant, is this appropriate?” I replied, “If it is heart failure, would you not use heart failure medications? This is TCM’s heart failure remedy.” As a result, after three consecutive days of treatment, the patient’s condition improved significantly, with a marked decrease in temperature to low fever and a pulse rate dropping below 100 beats per minute. This child is now in middle school. The effective component of Fu Zi that strengthens the heart is aconitine, and modern research has confirmed its reliable cardiotonic effects, improving peripheral and coronary blood circulation, increasing myocardial contractility, enhancing cardiac output, dilating peripheral blood vessels, and reducing peripheral resistance. In the past twenty years, there have been intramuscular injections or intravenous infusions of Ren Fu injection solution, which have effectively enhanced the emergency application of Fu Zi. In acute heat diseases, as well as in chronic conditions leading to congestive heart failure, Fu Zi is also effective. Heart failure fundamentally stems from Yang deficiency, with blood stasis and water retention as secondary issues. For heart failure presenting with palpitations, spontaneous sweating, shortness of breath, fatigue, and even cold limbs, edema, scanty urine, frequent night urination, pale tongue with white coating, and weak or irregular pulse, Mr. Zhu often uses Fu Zi as the main herb to invigorate the Yang of the heart and kidney, combined with Ren Shen, Fu Ling (Poria), Bai Zhu (White Atractylodes), Sheng Jiang (Fresh Ginger), Chi Bai Shao (Red and White Peony), Gui Zhi (Cinnamon Twig), Ting Li Zi, Xian He Cao (Agrimony), Dan Shen (Salvia), and Yi Mu Cao (Motherwort), achieving quick results. According to Zhongjing’s methods, Fu Zi is used for the urgent rescue of collapse, to restore lost Yang energy immediately, and must be used fresh, as its potency is initially strong. However, improper use of fresh Fu Zi can often lead to toxicity. Currently, fresh Fu Zi is often in short supply, and Mr. Zhu believes that using processed Fu Zi is also very effective, suggesting that it is not necessary to be overly rigid. Fu Zi warms the kidney Yang and is used for kidney Yang deficiency leading to inability to transform Qi and circulate fluids, resulting in edema (as in Ren Shen Tang (Ginseng Decoction), Zhen Wu Tang (True Warrior Decoction)), and for symptoms of frequent night urination, low back pain, and fatigue due to deficiency (as in Jin Gui Shen Qi Wan (Kidney Qi Pill)). In formulas for urinary stones, adding Fu Zi (3-5 grams) enhances stone expulsion. Fu Zi warms the spleen Yang and is effective for spleen Yang deficiency leading to poor transportation of food and fluids, resulting in chronic diarrhea or acute diarrhea damaging spleen Yang, often combined with Pao Jiang (Processed Ginger), Jiao Bai Zhu (Fried White Atractylodes), Fu Ling, Zhi Gan Cao, Ren Shen, and Fu Long Gan (Processed Dragon Liver), with slight additions of Wu Mei (Mume), Huang Lian (Coptis), achieving quick effects. Fu Zi also warms the lung Yang and liver Yang. In TCM terminology, lung Yang deficiency and liver Yang deficiency are not typically referred to, but in reality, lung Qi deficiency with cold symptoms indicates lung Yang deficiency (such as cough, wheezing, clear phlegm, cold back, and cold body); the liver is a solid organ, housing the fire of the heart. Liver Yin and blood are the foundation, while liver Yang and Qi are the functional aspects. Even when liver Yin and blood are abundant, there can be times when liver Yang and Qi are insufficient. Symptoms include fatigue, lack of joy, cold pain at the vertex, and dull pain in the hypochondrium and lower abdomen, with a cold sensation in the genital area. The pulse is wiry and slow. For lung Yang deficiency, Fu Zi can be combined with Gan Jiang (Dried Ginger) and Zhi Gan Cao (Honey-fried Licorice); for liver Yang deficiency, Fu Zi can be combined with Gui Zhi (Cinnamon Twig) and Huang Qi (Astragalus). Fu Zi is also a key herb for Bi syndrome, which encompasses a wide range of conditions, including rheumatoid arthritis, sciatica, ankylosing spondylitis, and periarthritis of the shoulder, among over twenty diseases. Mr. Zhu has accumulated decades of research on Bi syndrome, and his Yi Shen Juan Bi Wan (Kidney Invigorating and Bi Eliminating Pill) is renowned both domestically and internationally. For patients with stubborn conditions and severe pain, he often combines decoctions to quickly control symptoms and alleviate pain. Among these, for Bi syndrome with a cold component, Mr. Zhu often uses Fu Zi as the main herb, combined with Gui Zhi, Chi Shao (Red Peony), Bai Zhu, Gan Cao, Zhi Chuan Wu (Processed Aconite), Xi Xin (Asarum), Chuan Shan Long (Dichroa), and Sheng Jiang (Fresh Ginger). For Bi syndrome with wind, damp, and heat, Fu Zi is also used, often combined with Cang Bai Zhu (White Atractylodes), Huang Bai (Phellodendron), Can Sha (Silkworm Sand), Ren Dong Teng (Honeysuckle Vine), Bi Jie (Job’s Tears), Yi Ren (Coix), and Lao Guo Cao (Old Stork Grass). In these cases, Fu Zi is used because of the existing damp evil, as dampness is a Yin evil, and excessive dampness leads to weak Yang; on the other hand, due to the accumulation of damp heat, Yang energy is obstructed, thus Fu Zi’s great pungent and warming properties are utilized. Although Fu Zi is used in both cases, the combinations and dosages differ; for cold Bi syndrome, larger doses (15-30 grams) are required, while for heat Bi syndrome, smaller doses (3-6 grams) suffice. Periarthritis of the shoulder often requires Fu Zi, as patients frequently report cold sensations in the shoulder, fear of wind, and a preference for warmth, with increased pain at night when the shoulder is uncovered. Mr. Zhu’s experience is to use Fu Zi as the main herb, combined with Gui Zhi, Lou Feng Fang (Bee Nest), Qiang Huo (Notopterygium), Fang Feng (Siler), Jiang Huang (Turmeric), Hai Tong Pi (Alstonia), Chi Shao, Dang Gui (Angelica), Yin Yang Huo (Epimedium), Xi Xin, Wei Ling Xian (Clematis), Huang Qi, and Bai Zhu, with 15 doses per treatment course, often achieving effective results. Rheumatoid spondylitis, now known as ankylosing spondylitis, often requires large doses of Fu Zi combined with kidney-tonifying and blood-activating herbs, such as Lao Lu Jiao (Old Deer Antler), Yin Yang Huo, Shu Di Huang (Rehmannia), Bu Guo Zhi (Psoralea), Lou Feng Fang, Qi She (Chinese Water Snake), Ba Ji Tian (Morinda), Di Bie Chong (Earthworm), Chi Shao, and Hong Hua (Safflower), along with the oral intake of Yi Shen Juan Bi Wan. However, this condition is quite stubborn and requires persistent medication, as results are not seen in a short period. Not only for Bi syndrome, but many chronic inflammations also frequently use Fu Zi, such as chronic appendicitis, chronic nephritis, chronic pelvic inflammatory disease, and chronic bronchitis. Mr. Zhu believes that one should not shy away from using Fu Zi just because there is an “inflammation” involved; Fu Zi actually has good anti-inflammatory properties. Of course, the overall approach still adheres to the principle of differentiation and treatment. Additionally, Fu Zi can also be combined with herbs that clear heat and detoxify, as well as those that invigorate blood and resolve stasis. Zhongjing’s treatment of intestinal abscess with Yi Yi Fu Zi Bai Jiang San (Job’s Tears, Aconite, and Baijang Powder) has already set a precedent. Wang Ang’s “Ben Cao Bei Yao” (Essential Herbal Compendium) comprehensively and incisively describes the functions of Fu Zi: “Its nature is floating and not sinking, its use is swift and not stationary, it circulates through the twelve meridians, reaching everywhere. It can draw Qi tonics to restore lost Yang; draw blood tonics to nourish insufficient true Yin; promote dispersing herbs to open the pores and expel exterior wind and cold; and draw warming herbs to reach the lower jiao to dispel interior cold and dampness.” This can be referenced. In summary, Fu Zi has a wide range of clinical applications, and when used appropriately, its effects are remarkable. However, it should not be misused. Some doctors, due to its rapid effects in warming Yang and invigorating energy, often misuse Fu Zi. There have been reports of a certain famous doctor whose prescriptions included Fu Zi in every formula, and no patient was treated without it; others have written that Fu Zi can be added to any formula like adding MSG to enhance flavor, which betrays the spirit of differentiation and treatment and is inappropriate. All medicines have their pros and cons and must be used judiciously. Regarding the dosage and method of Fu Zi, Mr. Zhu has repeatedly pointed out to us: first, different individuals have different tolerances to Fu Zi; some can tolerate 30-60 grams without issue, while others may experience toxic reactions with just a few grams. Therefore, except in emergencies, caution should be exercised; it is advisable to start with a small dose (3-6 grams) and gradually increase if there are no reactions, generally aiming for around 30 grams. Once effective, there is no need to continue with large doses, and a gradual reduction can also be adopted. Second, the processing of Fu Zi involves soaking it in brine and then steaming it, which destroys its toxic components while preserving its effective ingredients. However, the steaming process is currently empirical, and it is recommended that research institutions conduct tests to provide optimal processing methods for manufacturers. The Japanese processing method involves high temperature and high pressure to destroy its aconitine lactone, making the decoction much safer, and there is no need for pre-boiling or prolonged boiling (of course, the dosage of Fu Zi in Japanese herbal medicine is very small). Given the current situation, if a larger dosage of Fu Zi is used, it is still advisable to use processed Fu Zi. It must be pre-boiled for half an hour, and it is best to add three to five slices of fresh ginger or a spoonful of honey during the boiling process. The experience of doctors in Sichuan is to taste it until there is no numbness in the mouth. If there is a tingling sensation in the mouth or tongue, it should be boiled again. Additionally, the water used to boil Fu Zi should be sufficient at once and not added midway. The first symptoms of Fu Zi toxicity are dizziness, palpitations, numbness of the mouth, tongue, lips, and limbs, and slurred speech. At this point, a large bowl of rice washing water can be taken immediately, which helps alleviate the symptoms of toxicity, followed by decocting 60 grams of licorice. In severe cases, in addition to the above symptoms, there may be nausea, vomiting, cold and wet skin, chest tightness, slow and weak heartbeat, low blood pressure, premature beats, arrhythmia, decreased body temperature, or sudden convulsions, and immediate hospitalization for emergency treatment is necessary.