Dyspepsia refers to chronic or recurrent upper gastrointestinal symptoms. According to the Rome IV criteria, functional dyspepsia (FD) symptoms included meal-related fullness, early satiation, epigastric pain or burning which are unexplained after routine investigation. FD causes substantial psychophysical burden because of its unknown etiology and high prevalence. Although FD is currently associated with local inflammation of the gastrointestinal tract and microbiota alteration, current available treatments for FD are of limited effectiveness. In view of this, many studies have applied Chinese herbal medicine in FD and achieved some therapeutic benefit. The Jing Si Herbal Tea composed of eight native Taiwanese herbs (wormwood, hickory grass, Ophiopogon japonicus, houttuynia cordata, platycodon, licorice, perilla leaves, chrysanthemum) has obtained a special export license from the Ministry of Health and Welfare. The Jing Si Herbal Tea also has been registered in clinical trials as a complementary treatment for COVID-19. The preliminary data demonstrated that the Jing Si Herbal Tea may improve gastrointestinal symptoms and anxiety in patients with COVID-19. Therefore, this study aims to investigate the impact of the Jing Si Herbal Tea on psychophysical burden and metabolites of microbiota in patients with FD through a double-blind randomized manner.

Inclusion Criteria:

1. Age between 20-79 years old.
2. Those who meet the definition of functional dyspepsia (FD). (Functional dyspepsia (FD) is chronic (once a week, lasting at least three months, at least six months before the first symptom) upper gastrointestinal symptoms (any of the following): postprandial abdominal distension, easy to feel full, Epigastric pain or burning sensation in the upper abdomen, and no symptoms of gastrointestinal bleeding or significant weight loss, no abnormality after upper gastrointestinal endoscopy).
3. Be conscious and willing to sign the subject's consent form.

Exclusion Criteria:

1. Abnormal liver and kidney function;
2. Abnormal blood tests and thyroid abnormalities;
3. Have received surgery on the digestive tract;
4. Abnormal upper gastrointestinal endoscopy;
5. Have gastric pylori infection;
6. Antibiotics are being used for infectious diseases;
7. Pregnant or breastfeeding women;
8. Suffering from heart, liver, or kidney failure;
9. Physical weakness, allergies, coldness, chronic diseases, poor kidney function, infants under three years old, children, Pregnancy, lactation, menstrual period.