Why do you sometimes feel a dry tongue?

Many tea enthusiasts have reported this situation: sometimes drinking tea can make you feel a dry mouth and tongue. Is this normal? Does it mean the tea leaves are of poor quality?

The reasons for this sensation are complex. We have summarized experiences from tea drinking to share with everyone. First, it is necessary to rule out the context of the drinker's own poor physical condition. Normally, the surface of the tongue is moistened by body fluids, reflected as moisture on the tongue surface. In traditional Chinese medicine, dryness or moisture reflects the condition of body fluids internally. A normal tongue coating is neither too dry nor too wet. Insufficient body fluids lead to a dry mouth and tongue. A dry, coating-less tongue indicates exhaustion of body fluids; for external afflictions, it's often due to dryness-heat damaging fluids, while for internal injuries, it's mostly due to yin deficiency and insufficient fluids. Frequent dry mouth and tongue have little direct relation to tea drinking itself, which is a separate matter.

Setting aside pathological reasons, let's look at the relationship between a dry tongue surface and tea drinking:

First, dryness and astringency caused by tea polyphenols. Tea contains polyphenolic substances. When these enter the mouth, they can form a water-impermeable film on the tongue, making the tongue feel dry and astringent. After this film breaks, it transforms into the commonly experienced 'sweet aftertaste' (hui gan), which is also a sign of good tea. This sensation is usually more pronounced in teas with higher polyphenol content, such as green tea and raw Pu-erh.

Second, caused by drinking tea too hot. While drinking tea hot or warm is recommended, consuming it overly hot can scald the oral cavity, creating a dry, rough feeling. In fact, drinking overly hot water produces a similar sensation. Furthermore, Li Shizhen's "Compendium of Materia Medica" mentions: "Tea is bitter and cold, most effective at lowering fire (internal heat). Fire is the root of all diseases; when fire descends, the upper body becomes clear. Drinking it warm allows the fire energy to descend due to the cold nature, while drinking it hot causes the tea to disperse upward with the help of the fire energy, and it also helps counteract the toxicity of alcohol and rich food."

Third, the so-called relatively strong "fire energy" of some teas. On one hand, traditional medicine holds that foods have "four natures and five flavors": cold, cool, warm, hot (the four natures) and sour, bitter, sweet, pungent, salty (the five flavors). Among tea types, green tea and white tea are the coolest, while partially oxidized teas (like oolong) and yellow tea are relatively neutral and mild, and black tea and dark tea (like Pu-erh) are relatively warm to hot in nature. On the other hand, some newly processed teas, such as green tea that has just undergone fixation and drying or teas that have just been roasted, often still have undissipated "fire energy." Drinking them at this stage can cause a dry, rough sensation on the tongue and throat for some people. For the vast majority of tea types, this condition does not occur after a period of resting/storage.

The above are the main reasons for a dry tongue. Additionally, some people are sensitive to tea fuzz (fine hairs). For teas with abundant fuzz like Biluochun or Silver Needle white tea, the throat might feel itchy and dry due to the stimulation.

Thus, we understand why sometimes drinking tea can cause a dry sensation on the tongue. In fact, similar to how we perceive other tastes, to some extent, it is actually a normal phenomenon, so there's no need to worry.