The physician prescribes bitter medicine, and it must be swallowed with a bitter taste. Why is that?
Decoctions made from Chinese herbal medicine are often intensely bitter, and many people cannot tolerate this bitterness and cannot drink it without sugar. In such cases, most people do not object to adding sugar, because various ready-made medicines sold in pharmacies, such as granules, syrups, and ointments, are all sweetened. In fact, this is merely knowing the "what" but not the "why." Whether sugar can be added to medicine, and if it can, is a profound and rigorous science.
First, the chemical composition of medicine is relatively complex. Sugar, especially brown sugar, contains more elements and impurities such as iron and calcium. Once these components react with proteins and tannins in the Chinese medicine, a chemical reaction will occur, causing some of the active ingredients in the medicinal liquid to coagulate and denature, subsequently becoming turbid and precipitated. This not only affects the efficacy of the medicine but also harms health.
Second, some medicines must use their bitterness to stimulate the secretion of digestive glands in order to be effective. If sugar is added, this effect is lost, and the therapeutic effect cannot be achieved.
Third, sugar can interfere with the absorption of trace elements and vitamins, inhibit the efficacy of certain antipyretic drugs, and degrade the active ingredients of certain drugs. For example, nux vomica is extremely bitter, and adding sugar would reduce its efficacy.