Agastache Coix Seed Watermelon Soup: Summer Medicinal Diet Recipe

Introduction to Medicinal Diet

Huoxiang Yiren Xigua Tang (Agastache rugosa, Coix Seed, and Watermelon Soup) is a classic summer medicinal dish that combines the dual effects of clearing summer-heat and relieving heat, as well as transforming dampness and strengthening the spleen. Derived from a folk recipe, this soup skillfully integrates the aromatic dampness-transforming Huoxiang (Agastache rugosa), the bland dampness-draining Yiyiren (Coix lacryma-jobi seed), and the sweet-cold summer-heat-relieving watermelon flesh. The soup has a clear broth, a fragrant aroma, and a sweet taste with a lingering aftertaste. During the scorching and humid days of summer, when damp-heat steams both externally and internally, a bowl of chilled Huoxiang Yiren Xigua Tang can both dispel external heat pathogens and resolve internal dampness turbidity, making it an excellent nourishing and refreshing product for summer health preservation.

The creative concept of this medicinal diet fully embodies the wisdom of “treatment according to seasonal conditions” and “homology of medicine and food” in Traditional Chinese Medicine. In summer, the body’s yang qi tends to float to the exterior, the interstices (cou li) are open and loose, and sweating increases, which can easily consume and damage body fluids (jin ye). At the same time, people often seek coolness by consuming cold drinks and raw, cold fruits, which can easily impair the yang qi of the spleen and stomach, leading to internal retention of dampness turbidity (shi zhuo). The Huoxiang Yiren Xigua Tang (Agastache rugosa, Coix Seed, and Watermelon Soup) is specifically designed to address these seasonal characteristics. It uses watermelon (xi gua) to clear heat and relieve summerheat (qing re jie shu), generate fluids and quench thirst (sheng jin zhi ke); Coix seed (yi ren) to fortify the spleen and drain dampness (jian pi shen shi), clear heat and expel pus (qing re pai nong); and Agastache rugosa (huo xiang) to aromatically transform dampness (fang xiang hua shi), harmonize the stomach and stop vomiting (he wei zhi ou). These three ingredients work synergistically, clearing without being cold, and draining without damaging the upright (zheng qi), making it highly suitable as a daily health beverage for modern people during the summer.

Historical Origins and Development

Upon consulting historical dietary therapy literature, although there is no direct record of a soup named “Huoxiang Yiren Xigua Tang” (Agastache, Coix Seed, and Watermelon Soup), the concept of combining Agastache rugosa (Huoxiang), Coix lacryma-jobi (Yiyiren, Coix Seed), and Citrullus lanatus (Watermelon) aligns with the approaches of many physicians from the Song, Yuan, Ming, and Qing dynasties in treating summer-heat dampness. For example, “Huoxiang Zhengqi San” (Agastache Qi-Correcting Powder) from the *Taiping Huimin Heji Ju Fang* (Imperial Grace Formulary) uses Huoxiang as the chief herb, specifically treating external contraction of wind-cold with internal damage of dampness stagnation. Meanwhile, the *Bencao Gangmu* (Compendium of Materia Medica) praises watermelon as “Tian Sheng Bai Hu Tang” (Heavenly Born White Tiger Decoction), a supreme product for clearing heat and relieving summer-heat. In folk practice, combining these three ingredients takes advantage of Huoxiang Zhengqi San’s ability to correct qi and watermelon’s ability to clear heat, with the addition of Coix seed to protect the spleen and stomach. Through generations of practice and refinement, this soup has evolved into an excellent medicinal and dietary summer health soup.

Therapeutic Effects of Medicinal Diet

The primary effects of Huoxiang (Agastache rugosa) Yiren (Coix seed) Watermelon Decoction are clearing heat and relieving summerheat, transforming dampness and harmonizing the middle jiao. It is particularly indicated for summerheat-dampness common cold with fever, restlessness, thirst, a heavy sensation in the head (as if wrapped), chest oppression and epigastric stuffiness, nausea and vomiting, and scanty dark urine. Watermelon pulp is rich in citrulline and lycopene, which rapidly replenish fluids and electrolytes lost through perspiration, effectively lowering body temperature and alleviating thirst and restlessness. Coix seed is abundant in coixenolide and dietary fiber, promoting the discharge of dampness from the body and improving the heavy, lethargic limbs and poor appetite characteristic of “bitter summer” (kuxia).

Furthermore, this medicinal food also has the effects of strengthening the spleen and stimulating appetite, as well as promoting diuresis and reducing edema. The volatile oil contained in *Agastache rugosa* (Huoxiang) can stimulate the gastric mucosa, promote gastric juice secretion, and enhance digestive function. *Coix lacryma-jobi* var. *ma-yuen* (Yiyiren) strengthens the spleen’s ability to transport and transform fluids, making it highly effective for common summer conditions such as lower limb edema, loose stools, and a white greasy tongue coating. For individuals who work or live in air-conditioned environments for prolonged periods, this soup can also help alleviate symptoms such as aching joints and muscle stiffness caused by “external cold and internal dampness.”

The Role of Traditional Chinese Medicine

According to the theory of TCM properties, flavors, and meridian tropism, watermelon is sweet and cold in nature, entering the Heart (HT), Stomach (ST), and Bladder (BL) meridians. Its core actions are to clear summer heat, relieve irritability and thirst, and promote urination. Summer heat is a yang pathogen, characterized by heat, upward dispersion, and the tendency to consume qi and injure body fluids. Watermelon’s sweet-cold properties directly enter the Heart and Stomach, purging scorching heat and allowing it to be released through urination, hence its reputation as the “natural White Tiger Decoction” (Bai Hu Tang). However, caution is warranted as watermelon has a strong purging and cooling effect; used alone, it may damage yang qi, so it should be combined with warming and tonifying herbs to moderate its coldness.

Coicis Semen (Job’s tears or coix seed) is sweet and bland in flavor, slightly cold in nature, and enters the Spleen (SP), Stomach (ST), and Lung (LU) meridians. Its actions are to promote urination and leach dampness, fortify the spleen and relieve impediment (bi), and clear heat and expel pus. In this formula, Coicis Semen serves two main roles: first, it assists Citrullus lanatus (watermelon) in promoting urination, allowing heat pathogen to be discharged through urination; second, it fortifies the spleen and dries dampness, preventing the coldness of watermelon from excessively damaging spleen yang. Pogostemonis Herba (patchouli) is pungent and slightly warm in nature, and enters the Spleen (SP), Stomach (ST), and Lung (LU) meridians. Its aromatic qi can awaken the spleen and transform dampness, harmonize the stomach and stop vomiting, which precisely counterbalances the cold nature of watermelon and Coicis Semen, so that the whole formula achieves “clearing within warming, draining within supplementing,” jointly accomplishing the effects of clearing summerheat and transforming dampness, and harmonizing and regulating the spleen and stomach.

compatibility mechanism

The exquisite nature of the whole formula lies in the “combined use of cold and warm” herbs. Watermelon (Citrullus lanatus) and Coix Seed (Semen Coicis) are both cold and cool in nature; although they strongly clear summerheat and drain dampness, prolonged use can easily damage the Middle Yang, leading to abdominal pain and diarrhea. Agastache rugosa (Patchouli) is warm in nature and aromatic; it can both diffuse and transform damp turbidity, and warm the Middle Burner to harmonize the Stomach, preventing excessive coldness. The three herbs are decocted together, so that heat is cleared without causing stasis, and dampness is removed without damaging yin, precisely aligning with the TCM therapeutic principle of “clearing heat without hindering dampness, and transforming dampness without aggravating heat.” This formula is especially suitable for the “Summerheat-Dampness mixed pattern” constitution commonly seen in modern society due to dietary irregularities and imbalances between work and rest.

Suitable Population

Agastache, Coix Seed, and Watermelon Soup is most suitable for individuals during the summer-damp season who present with “excessive fire” symptoms accompanied by “heavy dampness” manifestations. Typical candidates include: those working or living in hot and humid environments for prolonged periods, such as construction workers, traffic police, and sanitation workers—these individuals are prone to summer-heat symptoms like body heat, thirst, irritability, dizziness, fatigue, and scanty dark urine; as well as those with irregular dietary habits, a preference for rich, fatty, sweet, or raw and cold foods, who often experience epigastric distension and fullness, a sticky sensation in the mouth, and unsmooth defecation—drinking this soup can aid digestion and resolve damp turbidity.

Furthermore, this medicinal food is especially recommended for children and the elderly who suffer from poor appetite due to summer-heat, as well as for individuals prone to acne, folliculitis, and other conditions caused by damp-heat accumulating in the skin on the face or back during summer. The heat-clearing action of watermelon (Citrullus lanatus) combined with the pus-draining effect of Coix (Coix lacryma-jobi var. ma-yuen, Job’s tears) helps improve inflammatory skin reactions. For those experiencing mild prodromal signs of heat stroke after outdoor summer exercise—such as dizziness, nausea, and elevated body temperature—it can also serve as an emergency drink to rapidly replenish fluids and electrolytes and alleviate discomfort.

Contraindicated populations

Although Huoxiang Yiren Xigua Tang (Agastache, Coix Seed, and Watermelon Decoction) is mild in nature, certain contraindications should still be observed. Individuals with Spleen and Stomach Yang Deficiency—those who typically experience aversion to cold, cold extremities, epigastric and abdominal cold pain, loose and watery stools, and a pale, enlarged tongue with tooth marks—should avoid prolonged or excessive consumption, as it may further aggravate the deficiency-cold pattern, potentially leading to diarrhea or stomach pain. Both watermelon (Citrullus lanatus) and Coix seed (Coix lacryma-jobi) are sweet and cold in nature; although Agastache (Agastache rugosa) is warming, its dosage is limited, making the overall formula relatively cool in property. Those with insufficient Spleen and Stomach yang may experience adverse reactions such as abdominal distension, borborygmus, and loose stools after consumption.

In addition, caution should be exercised in pregnant and lactating women. Coix seed (Semen Coicis) has a traditional property of “causing miscarriage” (huá tāi) in classical Chinese materia medica. Ancient texts such as *Bencao Jingshu* record that it “specifically promotes urination and is contraindicated in pregnancy.” Modern pharmacological studies also suggest that Coix seed extract has a stimulatory effect on uterine smooth muscle; therefore, it should not be used during pregnancy. Menstruating women with a Cold constitution or accompanying dysmenorrhea should also avoid consumption. Diabetic patients may consume a small amount, but should accordingly reduce their staple food intake for the day and monitor blood glucose changes. For those with severe cardiac or renal insufficiency, assessment of suitability should be conducted under the guidance of a physician.

Ingredient Formula Ratio

Classic Formula Proportions (for 2-3 servings): Watermelon flesh (Citrullus lanatus) 500 g (net weight after peeling, preferably red-fleshed, moderately ripe watermelon), Raw Coix seed (Coix lacryma-jobi) 30 g (preferably plump, white grains), Dried Patchouli leaf (Pogostemon cablin) 10 g (or fresh Patchouli leaf 20 g, preferably whole leaves with strong aroma). Optional adjuncts: rock sugar 15 g (or honey to taste, can be replaced with steviol glycosides for diabetic patients), and purified water 1500 ml.

When selecting ingredients, note the following: Watermelon can be either sandy-fleshed or crisp-fleshed, but avoid artificially ripened or spoiled watermelon. Before use, Coix seed (Semen Coicis) should be checked for mold or insect damage, rinsed twice with clean water, and soaked for 1 hour. For Agastache (Huoxiang), the geo-authentic varieties from Guangdong or Hainan are preferred; dried products should be stored in a sealed, light-proof container. If fresh watermelon is unavailable, Watermelon Exocarp (Xiguacuiyi, the outer green part of the rind) can be used as a substitute at half the dosage (250 g), though the effect will be slightly inferior. To enhance the dampness-resolving action, add 3 g of Tangerine Peel (Chenpi) and 2 slices of Fresh Ginger (Shengjiang) to help move Qi and dry Dampness, as well as warm the Middle Burner and arrest vomiting.

Preparation Method

Step 1: Preparation. Soak the raw Coix seed (Coix lacryma-jobi) in cold water for at least 2 hours in advance (if time is limited, soak in warm water for 40 minutes) to allow full water absorption and expansion, making it easier to cook thoroughly. Cut the watermelon flesh into small cubes of about 2 cm and place them in a bowl for later use. Gently rinse the dried patchouli leaf (Agastache rugosa) under running water to remove any surface dust, then drain well.

**Step 2: Decoction of Coix Seed.** Prepare a clay pot or stainless steel soup pot. Pour in 1500 ml of purified water and add the soaked Coix seeds (Semen Coicis). Bring to a boil over high heat, then reduce to low heat, cover, and simmer gently for 40 minutes until the seeds are completely soft and the liquid turns milky white. Stir occasionally to prevent sticking. **Do not use an iron or aluminum pot**, as these metals may compromise both the therapeutic effect and the color of the decoction.

Step 3: Add the watermelon and Agastache rugosa (Korean mint). Once the Coix seed (Job’s tears) is cooked, adjust the heat to medium. Add the watermelon chunks and Agastache rugosa leaves (if using fresh leaves, add them in the last 5 minutes). Continue cooking for 5 minutes, until the watermelon flesh softens slightly and the soup turns light red, then turn off the heat. Do not cook for too long, otherwise the sweet flavor of the watermelon will dissipate excessively and the volatile oils of the Agastache rugosa will be lost entirely. After turning off the heat, add rock sugar and stir using residual heat until dissolved.

Step 4: Filtering and Seasoning. Filter the cooked soup through a fine mesh sieve, removing the Agastache rugosa (Huoxiang) leaf residue and watermelon fibrous bits, retaining only the clear broth. When the broth has cooled to warm (approximately below 40°C), a small amount of honey can be added for flavor according to personal preference. In summer, it can be refrigerated for 1 hour before drinking for a better cooling effect, but for those with Spleen and Stomach Deficiency Cold pattern, warm consumption is recommended.

Consumption Tips

1. There are specific considerations regarding the optimal time for consumption. This soup is best taken between 2 and 4 PM, when yang qi gradually declines and summer-heat is at its peak — the period when the body is most vulnerable to summer-heat invasion. A bowl of medicinal dietary soup at this time provides excellent prevention and relief. It should not be consumed on an empty stomach in the morning or before bedtime at night, as the cold nature may irritate the gastrointestinal tract or lead to nocturia. It is recommended to take it 2 to 3 times per week, for no more than 5 consecutive days, to avoid excessive diuresis that could cause electrolyte imbalance.

2. Individualized Proportion Adjustment. According to individual body constitution, the ingredient proportions can be flexibly adjusted: Those with more intense internal heat and a tendency toward dry mouth and throat may appropriately increase watermelon proportion to 600 grams; those with heavy dampness and a thick, greasy tongue coating may increase Coix seed (Semen Coicis) to 40 grams and add 3 grams of Poria (Poria cocos); if a cold sensation in the stomach is experienced after consumption, add 2 slices of fresh ginger (Zingiber officinale) or 1 red jujube (Ziziphus jujuba) during preparation to warm the middle burner and disperse cold, thereby harmonizing the medicinal properties.

3. Storage and reprocessing of leftover decoction. If a large quantity is prepared at once, pour the strained clear decoction into a sealed glass bottle and refrigerate for no more than 24 hours. Before re-consumption, it must be boiled to sterilize, but the boiling time should be limited to within 1 minute to prevent excessive degradation of the active medicinal constituents. Freezing is not recommended, as thawing will severely impair the fresh, sweet taste of watermelon and increase suspended solids, affecting visual appeal. If the decoction develops a sour odor or flocculent precipitate, it indicates spoilage and should be discarded immediately and not consumed.