In a broad sense, the decoction of traditional Chinese medicines encompasses both herbal teas and powdered decoctions; the intensity of heat, the solvent used, and any auxiliary ingredients employed during the decoction process can all influence the medicinal properties and therapeutic efficacy. Ancient texts on TCM record instances of medicines being decocted in ice, as well as in sugarcane juice, boiling hot water, liquor, honey, and other solvents or auxiliary agents. It is thus evident that the choice of “water” for decocting Chinese herbs—the selection of the decoction solvent and auxiliary ingredients—is indeed a matter requiring careful consideration. The following section introduces several commonly used decoction solvents.

The Compendium of Materia Medica records: “Emperor Huizong of the Song Dynasty indulged excessively in iced drinks, which damaged his spleen and stomach. The imperial physicians were unable to cure him, so they summoned Yang Jie to examine him. Jie prescribed Dali Zhong Wan. The emperor said, ‘I have taken this medicine many times already.’ Jie replied, ‘The illness arose from the consumption of iced drinks; therefore, I have prepared this formula by decocting it in ice—this addresses the root cause of the disease. Indeed, after taking it, he was cured.’” In other words, Emperor Huizong’s excessive fondness for iced beverages had harmed his spleen and stomach. The imperial physicians diagnosed this as a condition in which cold pathogenic factors had invaded the middle burner and prescribed Dali Zhong Wan, but the treatment proved ineffective. The renowned folk physician Yang Jie then suggested using ice to decoct the medicine, and sure enough, the emperor recovered.

From a chemical standpoint, ice and water are the same substance; however, when used as solvents in decocting herbal medicines, they produce different effects. Why is this the case?

According to Traditional Chinese Medicine, Emperor Huizong of the Song Dynasty’s illness was caused by excessive consumption of ice, which led to the accumulation of cold pathogenic factors in the middle jiao—the spleen and stomach. Dali Zhong Wan possesses the therapeutic effects of warming the middle burner and dispersing cold, making it a perfect match for the patient’s pattern and an accurate choice of formula. However, since Emperor Huizong’s condition was one of cold, while the medicine itself is warm and drying, the opposing natures of cold and heat would counteract each other, thereby compromising the therapeutic efficacy. In TCM, this phenomenon is referred to as “cold–heat antagonism.” Later, Yang Jie suggested using ice water during the decoction process because the cooling nature of ice not only mitigates the warmth and dryness of the herbal mixture but also serves as an auxiliary agent. Since ice water shares the same cold nature as the patient’s underlying cold pattern, it harmonizes with the pattern and eliminates the state of cold–heat antagonism, thus enabling the medicine to effectively cure the disease.

Using a cold and cooling solvent to decoct herbs can enhance their inherent cold and cooling properties while mitigating their warming and heating nature. Take the commonly consumed sugarcane as an example: it is cold in nature and sweet in taste, with the effects of clearing heat, moistening dryness, relieving thirst, and eliminating phlegm. The classical formula “Qu Fan Yang Wei Tang” specifically uses a decoction of sugarcane in place of water, thereby strengthening the entire formula’s ability to clear heat, generate body fluids, and moisten dryness, thus effectively resolving heat syndromes in the middle burner.

There is also a traditional practice of decocting herbs in wine. Wine is warm in nature and pungent in flavor; it can unblock the meridians, relieve bi syndrome, warm the blood vessels, and disperse stagnation. In the “Jin Gui Yao Lue,” there is a recipe called “Hong Lan Hua Jiu” for treating abdominal pain in women caused by blood-stasis and qi stagnation. In this formula, safflower promotes blood circulation and resolves stasis; when decocted solely in wine, the pungent flavor of the entire formula is intensified, thereby doubling its efficacy in invigorating blood, eliminating stasis, and relieving pain. However, individuals with alcohol allergies and motor vehicle drivers should use this preparation with caution.

Honey tonifies the middle jiao and replenishes qi, moistens dryness, relieves pain, and detoxifies; it can also be used as a solvent for decocting herbs. The “Jin Gui Yao Lue” records the Wutou Decoction for treating bi syndrome characterized by joint pain that renders flexion and extension impossible, in which Aconite is decocted with honey. The purposes of this formulation are twofold: first, to harness honey’s detoxifying properties to mitigate the toxicity of Aconite; second, to take advantage of honey’s sweet and gentle nature to temper Aconite’s pungent and rapid action, thereby allowing its dispersive and cold-dispelling, pain-relieving effects to unfold gradually and effectively eliminate lingering, chronic cold stagnation.

The method of decoction plays a crucial role in determining the therapeutic properties of Chinese medicinal herbs, and particular attention should be paid to the solvent and auxiliary ingredients used in the process. Therefore, after obtaining your prescription from the pharmacy, be sure to ask the pharmacists for clear instructions on the proper decoction techniques, so as to avoid delaying treatment due to improper preparation.