Also known as bougainvillea, it is a plant of the family Sanbaiaceae, and its young leaves are edible. “Compendium of Materia Medica”: “Treatment of phlegm and heat in the lungs, hair is the key medicine for pulmonary abscess and vomiting of pus and blood.” Therefore, the main function of this plant is to clear away heat, detoxify and eliminate lung abscess (that is, respiratory tract infection disease). Literature reports indicate that Houttuynia cordata can be antiviral, antibacterial, diuretic, anti-inflammatory, and anti-Staphylococcus aureus and Escherichia coli. The whole herb extract can inhibit leukemia cells through the mechanism of apoptosis. Water extract has inhibitory effect on inflammatory factors. Clinical practice has proved that Houttuynia cordata has curative effects on upper respiratory tract infection, bronchitis, pneumonia, whooping cough, etc. In addition, quercetin contained in Houttuynia cordata has the effect of inhibiting human immunodeficiency virus (HIV) and inhibiting coronavirus.

It is the stem and leaf of perilla, a plant of Labiatae, which is often used to treat cough and phlegm. “Compendium of Materia Medica” states that its effect is sweating, relieving the exterior, promoting qi and widening the middle, and it is clinically used for the effects of wind-cold and cold, dispelling exterior cold, and sweating. For symptoms such as chest tightness and nausea, using perilla is also effective.

Pungent and cool in nature and flavor, it returns to the two meridians of the lung and liver, and is often used to dissipate heat, soothe the liver and relieve depression. Mint has a wide range of uses, and the common mint is a species of the genus Mentha of the Lamiaceae. Clinically, it is often used to treat fever and cough symptoms caused by wind-heat and cold. “Compendium of Materia Medica” records: Peppermint can disperse pungently, cool and benefit, and is specially used for eliminating wind and dissipating heat. Huang Yijia, director of the Department of Traditional Chinese Medicine of the Third General Association, said that when viruses and bacteria first enter the human body, they will produce an immune response and cause physical discomfort. Using peppermint can regulate part of the immune response and improve cold symptoms.

Sweet and warm in nature, it belongs to the leguminous plant and is a Qi-invigorating material for both medicine and food. It belongs to the spleen meridian (stomach function) and lung meridian (respiratory system, skin), so it can enhance yang energy, solidify the body surface from the invasion of evil spirits, and have the function of preventing colds. In addition, Astragalus also inhibits inflammation, improves immune function and treats diseases caused by weakness.

Sweet in taste, flat in nature, homecoming to heart, lung, spleen, stomach meridians. The main functions are to invigorate the spleen and replenish qi, clear heat and detoxify, eliminate phlegm and relieve cough, relieve spasm and relieve pain, and reconcile various medicines. Clinically, it has the effects of nourishing the lungs and relieving cough, eliminating phlegm and promoting body fluid, clearing away heat and purging fire and detoxifying, and can be used for sore throat, sore tongue, carbuncle and sore. Modern pharmacology has found that licorice can enhance immunity, anti-inflammation, anti-virus, anti-bacterial, anti-ulcer, protect liver and gallbladder, antitussive and expectorant, lower blood fat, resist atherosclerosis, detoxify, and anti-tumor. In addition, if the nature of a certain medicine in the compound Chinese medicine is too partial or too cold, licorice is often used to reconcile the overall property of the medicine and improve the curative effect, so licorice has the reputation of “old country”.

“Compendium of Materia Medica” records that ginger is pungent and warm, and belongs to the five internal organs, eliminates wind, cold and heat, eliminates phlegm and lowers qi. Ginger has been proven by traditional Chinese medicine to have the effect of warming the lungs, relieving cough and reducing phlegm. Ginger contains various ingredients such as gingerol, which can enhance the antibacterial ability in the stomach and intestines, thus winning the reputation of “the holy medicine for the spleen and stomach”. Additionally, a 2013 study at Kaohsiung Medical University in Taiwan found that ginger can inhibit the growth of respiratory viruses such as RSV. Therefore, the function of ginger in Yiqing tea not only can moderate the coldness of other medicinal materials, but also improve lung function, including the effects of relieving cough, reducing phlegm and inhibiting respiratory viruses.