At one in the morning, the city falls silent, yet you toss and turn, unable to sleep. A burning pain radiates from the tip of your tongue, like a tiny needle repeatedly piercing the same spot. Oral ulcers — this seemingly insignificant "minor ailment" — why do they always visit in the dead of night? Healed and then recurring, recurring and then healing, as if locked in a tug-of-war with no end. Traditional Chinese Medicine holds that the twelve meridians of the human body correspond to the twelve double-hours. Zi hour (23:00–1:00) is governed by the Gallbladder meridian, and Chou hour (1:00–3:00) is governed by the Liver meridian. If at this hour — when one should be "lying down so that blood returns to the liver" — you remain awake, the movement of qi and blood in your body begins to deviate from its proper course. This, perhaps, is one key to understanding why oral ulcers recur persistently, healing only to return again.
Tracing the Causes: Where Does the Fire Come From, and Why Won't It Leave?
Recurrent oral ulcers heal and then reappear. In TCM clinical practice, this is often not simply "excess fire." If only one or two sores occasionally appear and subside after drinking some cooling herbal tea, it is mostly caused by excess fire. But if the ulcers come in waves, lingering and difficult to heal, one must ask: Where does this fire come from? Is it from what you eat? From staying up late? Or from suppressed emotions? Clinically, the combination of prolonged late nights, irregular diet, and repressed emotions most easily plunges the body into a complex state where "deficient fire" and "excess fire" intertwine. Deficient fire arises from insufficient yin fluids; excess fire arises from accumulated heat that has not been cleared. The two often coexist, like dry kindling meeting a blazing flame — reigniting at the slightest provocation. So then, is it primarily yin deficiency, or primarily excess heat? This requires careful differentiation.
Locating the Disease: The Diagnostic Maze of Organ Attribution
The Huangdi Neijing states: "The spleen opens into the mouth, and its brilliance manifests on the lips." > The mucosal condition of the oral cavity is closely related to the function of the spleen and stomach. If ulcers mostly occur on the tongue surface or inside the lips, accompanied by bad breath and sticky stools, then the disease location is likely in the spleen and stomach, belonging to "damp-heat in the spleen meridian" or "blazing stomach fire." Zusanli, also known as Xialing or Sanli, is located on the anterior-lateral aspect of the lower leg, 3 cun below Dubi, one finger-breadth from the anterior crest of the tibia. It belongs to the Foot Yangming Stomach meridian and serves as the He-Sea point of the Stomach meridian and the lower He-Sea point of the Stomach. The Lingshu says: "When pathogenic factors are in the spleen and stomach, there will be muscle pain... all are regulated at Zusanli." As a gathering point for the qi and blood of the Stomach meridian, Zusanli is closely associated with the transforming and transporting functions of the spleen and stomach, and is an acupoint that cannot be overlooked when understanding the spleen-stomach pathogenesis of oral ulcers. However, if ulcers are concentrated on the tip or edges of the tongue, accompanied by heart vexation, insomnia, and scanty dark-yellow urine, then one must consider "hyperactive heart fire" or "non-interaction between heart and kidney." Clinically, there is another situation easily overlooked — ulcers recurring at the root of the tongue or near the throat, accompanied by dry throat, dry mouth, and soreness and weakness of the lower back and knees. This often points to depletion of kidney yin, with deficient fire flaming upward. All three appear to be "fire," but the nature and source of the fire are entirely different, and the direction of treatment naturally differs vastly.
Differentiating the Nature of the Disease: The Yin-Yang Contest Between Deficiency, Excess, Cold, and Heat
Recurrent oral ulcers heal and then reappear. Some people are of a "heat" constitution — the mouth burns with pain, they crave cold drinks, and the tongue is red with yellow coating. Others are of a "cold" constitution — the ulcers are pale, the pain is not severe, yet they have cold limbs and loose stools. This is not contradictory. TCM emphasizes "treating the same disease with different methods." Behind the same symptom may lie completely opposite constitutional types. If one simply assumes that oral ulcers mean "excess fire" and blindly uses cold and cooling herbs, symptoms may be temporarily suppressed, but the yang qi of the spleen and stomach is damaged, leading to more severe deficiency-cold, and the ulcers actually flare up more frequently. Clinically, many people with recurrent oral ulcers are fundamentally in a state of "upper heat, lower cold" — deficient fire above, excess cold below. How to determine this? Observe the stools: if stools tend to be dry, it is mostly heat; if stools tend to be loose, it is mostly cold. Observe the tongue coating: if the tongue is red with little coating, it is mostly yin deficiency; if the tongue is pale and swollen with teeth marks, it is mostly yang deficiency. Taixi, also known as Lüxi, is located in the depression between the tip of the medial malleolus and the Achilles tendon. It belongs to the Foot Shaoyin Kidney meridian and serves as the Shu-Stream point and Yuan-Source point of the Kidney meridian. Kidney yin is the foundation of all yin fluids in the body. Taixi is directly related to the abundance or decline of kidney essence and kidney yin, and is often used as an important reference for identifying yin-deficient constitution. It is also one of the key acupoints for understanding the pathogenesis of "deficient fire flaming upward."
Predicting the Disease Trend: The Chain Reaction from Mouth Sores to the Whole Body
Recurrent oral ulcers heal and then reappear. If left unchecked, or if incorrectly treated, how will the disease progress? In the early stages, it may only be a localized inflammatory reaction of the mucosa, but over time, the transforming and transporting functions of the spleen and stomach become impaired, qi and blood generation becomes insufficient, and immunity declines. Even more alarming is that if this "deficient fire" state persists, it will gradually consume body fluids, leading to depletion of kidney yin, and even systemic problems such as insomnia, anxiety, and irregular menstruation. The Shanghan Lun mentions: "The disease of Shaoyang is characterized by bitter taste in the mouth, dry throat, and dizziness." > Recurrent oral ulcers are sometimes also a signal of dysfunction of the Shaoyang pivot, meaning that the ascending, descending, exiting, and entering of the body's qi mechanism have gone awry. If accompanied by distension and fullness in the chest and hypochondrium and significant emotional fluctuations, then it is not merely an oral problem, but an imbalance of the entire half-exterior, half-interior system.
Prognosis: When to Seek Professional Help
Recurrent oral ulcers heal and then reappear. In most cases, they are self-limiting and can heal on their own within about a week. However, if the following signals appear, it indicates that they need to be taken seriously: more than three ulcers that persist for over two weeks without healing; ulcers with irregular shapes, raised edges, and hard texture; or accompanying systemic symptoms such as fever, joint pain, and skin rashes. Clinically, if some individuals simultaneously experience eye discomfort and genital ulcers, it may fall within the category of "Behçet's disease" and should not be treated simply as ordinary oral ulcers. In addition, ulcers caused by long-term use of certain medications (such as immunosuppressants and antitumor drugs) also need to be distinguished from ordinary ulcers. In these situations, one should promptly visit a licensed medical institution for a comprehensive evaluation by a licensed TCM practitioner or Western medicine physician.
Care Approaches: Following the Timing of Heaven, Harmonizing Yin and Yang
Since oral ulcers are closely related to time of day and constitution, care approaches should also start from "regulating timing" and "regulating constitution." Adjusting one's sleep schedule is the first thing to do: try to fall asleep before Zi hour, allowing the Gallbladder and Liver meridians to rest fully, which helps with the generation and free flow of qi and blood. In terms of diet, avoid excessive spicy, grilled, and fried foods, as these foods fuel "excess fire"; at the same time, also reduce raw, cold, and cooling foods to avoid damaging spleen yang and aggravating "deficiency-cold." Emotional management is equally crucial: long-term suppression and anxiety can cause liver qi stagnation that transforms into fire, and this "stagnant fire" most easily attacks the oral cavity. One can try to relieve emotions through walking, meditation, or confiding in friends. As for specific food choices, such as consuming appropriate amounts of Chinese yam, lily bulb, and lotus seed, these may be helpful for yin-deficient constitutions, but the specific plan must be determined by a licensed TCM practitioner based on individual constitution, and should not be blindly imitated. Zhaohai is located on the medial aspect of the foot, in the depression below the tip of the medial malleolus. It belongs to the Foot Shaoyin Kidney meridian and connects with the Yin Qiao vessel. This acupoint has a certain association with the moistening of the throat and oral cavity by body fluids, and is of reference significance in understanding "deficient fire flaming upward" and "insufficient yin fluids."
Frequently Asked Questions
Q: Why is it that for the same oral ulcers, some people respond to heat-clearing herbs while others improve with warming and tonifying herbs?
A: This stems from constitutional differences. For those with an excess-fire constitution, heat-clearing herbs are like removing the firewood from under the cauldron and are naturally effective. But for those with deficient fire or an upper-heat-lower-cold constitution, heat-clearing herbs will instead aggravate the lower cold, causing the deficient fire to burn even more intensely. The core of TCM is "treatment based on pattern differentiation," not "matching symptoms to prescriptions."
Q: Are recurrent oral ulcers and low immunity the same thing?
A: Not entirely equivalent. TCM holds that low immunity is mostly related to "qi deficiency" and "yang deficiency," while recurrent oral ulcers involve more complex pathogenesis such as "yin deficiency," "stagnant fire," and "damp-heat." The two overlap, but the treatment directions differ and cannot be simply equated.
Q: Why do some people find their oral ulcers worsen after eating a lot of fruit?
A: Fruits have different natures. Watermelon and pear are cooling and may help with excess-heat patterns; but lychee, longan, and mango are warming and easily fuel fire and generate heat. In addition, overconsumption of raw and cold fruits can damage spleen yang, leading to internal generation of damp turbidity, which stagnates and transforms into heat, actually aggravating the ulcers.
Q: Does recurrent oral ulcers mean the body has "toxins"?
A: TCM does not emphasize the concept of "detoxification" but focuses more on "qi mechanism" and "yin-yang balance." Recurrent ulcers are more like the body sending a signal — that "qi" somewhere has become blocked, or that the balance between "yin" and "yang" has been disrupted. Unblocking rather than opposing, nourishing rather than attacking — this is the way of long-term health.