Phragmites

Phragmites (Phragmites australis / Phragmites communis): A Comprehensive Reference

1. Identity and Botanical Description

Taxonomy and Nomenclature

Phragmites australis, also known as P. communis or the common reed, is a tall, perennial helophyte with a large network of robust underground rhizomes. The plant belongs to the Poaceae family, also known as Gramineae. According to recent taxonomic classifications, the genus Phragmites includes four species that are recognized by the World Checklist of Poaceae and The Plant List: Phragmites australis (Cav.) Trin. ex Steud. being the primary species of medicinal interest. The full accepted scientific binomial is Phragmites australis (Cav.) Trin. ex Steud., with Phragmites communis Trin. recognized as a widely used synonym, particularly in Chinese and Korean pharmacopeial contexts.

The rhizome of Phragmites communis Trinius is listed in the Korean Pharmacopoeia as "No-Geun" and in the Chinese Pharmacopoeia as "Lu Gen." The medicinal preparation Phragmitis rhizoma, or Lu Gen in Chinese, is the fresh or dried rhizome of the perennial grass Phragmites communis Trin., a synonym of Phragmites australis (Cav.) Trin. ex Steud.; it is widely distributed throughout the world, especially in wetlands, marshes, and lakes.

Morphology and Habitat

The common reed is a tall perennial grass, reaching 2–4 meters high, with robust rhizomes that form dense colonies. Stems are erect, hollow, and ridged; leaf blades up to 60 cm long, flat and tapering. In late summer, plume-like inflorescences appear, silky gray-brown. It is adapted to freshwater marshes, riverbanks, and brackish wetlands across temperate zones of Europe, Asia, and North America. It grows particularly on nutrient-rich peatlands, riverbanks, as well as lake and gulf shorelines. It is a hydrophytic species inhabiting riverbanks, fresh swamps, and lakes and grows well in temperate climates such as Japan, China, and Korea.

Medicinal Plant Parts and Common Preparations

The rhizomes, or underground stems, are the most commonly used medicinal part and are known in Traditional Chinese Medicine (TCM) as Lu Gen. Phragmitis rhizoma, or Lu Gen in Chinese, is the fresh or dried rhizome of the perennial grass Phragmites communis Trin., widely distributed throughout the world, especially in wetlands, marshes, and lakes. In addition to the rhizome, various scientific studies have investigated the leaves, stems, roots, and flowers of the plant for their phytochemical constituents. The chemical constituents of Phragmitis Rhizoma include polysaccharides, flavonoids, steroids, anthraquinones, alkaloids, volatile components, small molecules, and other components.

Preparations reported in the scientific literature and traditional sources include:

• Decoction (water decoction): The fresh or dried rhizome boiled in water; the most classical form described in historical Chinese and Korean medicine texts.
• Aqueous extract: Used extensively in modern laboratory studies assessing biological activities.
• Polysaccharide-rich extract: Isolated fractions used in dermatological and immunological research.
• Ethanolic or organic solvent extracts: Used in pharmacological screening studies.
• Patent Chinese medicines: Formulas including P. communis include Ganmao Qingre granules, antiviral oral liquid, Siji antiviral mixture, and Yin Qiao San; Ganmao Qingre granules, antiviral oral liquid, and Yin Qiao San are included in the Pharmacopoeia of the People's Republic of China 2020.

2. Traditional and Historical Use

Traditional Chinese Medicine (TCM)

As a common traditional Chinese medicine, P. communis has been utilized in clinical practice in China for over 2,000 years. The ancient book The Famous Doctor's Book (《名医别录》), compiled by Tao Hongjing around the 4th century AD, describes its medicinal use. Specifically, that text describes the use of P. communis to alleviate thirst related to consumption, reduce fever caused by yin deficiency, and alleviate frequent urination.

According to the Pharmacopoeia of the People's Republic of China 2020, P. communis is characterized by its ability to clear heat and reduce fire, nourish yin, and generate fluid. Rhizoma phragmitis is a common Chinese herbal medicine whose effects are defined as "clearing heat and fire, promoting fluid production to quench thirst, eliminating irritability, stopping vomiting, and disinhibiting urine." Traditionally, Phragmites root was employed to relieve fever, quench thirst, and promote urination. It was highly valued as a remedy for high fevers, lung abscesses, and coughs associated with thick phlegm, helping to clear heat and generate fluids. Additionally, it has been used to alleviate nausea and vomiting, especially in cases linked to stomach heat or infections, and to support recovery from illnesses that deplete bodily fluids.

In Chinese folk medicine, the rhizome has also been used for the treatment of lung diseases. During the Novel Coronavirus epidemic in 2020, the Weijing Decoction and Wuye Lugen Decoction, with Rhizoma phragmitis as the main herbal component, were included in The Pneumonia Treatment Protocol for Novel Coronavirus Infection (Trial Version 5) due to reported antiviral effects.

Traditional Korean Medicine

In Korea, the fresh or dried rhizome of P. australis has long been recommended for relieving fever and vomiting as well as to promote diuresis. It has been prescribed in traditional Korean and Chinese medicine to relieve fever, vomiting, dysuria, and constipation.

North African and Mediterranean Traditions

P. australis is known for its pharmacological, ecological, and therapeutic properties, as it is rich in active biological substances. Many people from all over the world have used it in traditional medicine, including in North African countries, especially Algeria, where it is used to treat many organic and infectious conditions. In addition to being used as a medicinal plant in Asian, central European, and Mediterranean nations, Phragmites australis is also widely employed in Algerian traditional medicine.

Ethnobotanical Uses in Anatolia (Turkey)

In Afyonkarahisar Province of Western Anatolia, the plant has been utilized for various applications including heat insulation, sound insulation, wrapping and protecting corpses in graveyards, medical uses, animal shelters, fence construction, nests for migratory birds, mat weaving, tents, roofing, and foods. As an example of its medical use, local peasants boil Phragmites australis by the decoction method and drink the preparation.

Native American and Historical Western Uses

Common reed was used for thatching Native American houses and in the construction of items such as clothing, nets, snares, sleeping mats, wooden frames for drying berries, and sandals. It was also used as a source of salt and smoking tobacco. Historical Mesoamerican and indigenous North American communities are documented in the ethnobotanical literature as having leveraged the plant for food and medicinal purposes; Daniel Moerman's compendium of American Indian Ethnobotany lists several medicinal uses.

Persian and Other Historical Traditions

In ancient Persia, early physicians like Avicenna mentioned reed rhizomes for their diuretic and anti-inflammatory properties.

3. Phytochemistry: Key Constituents and Active Compounds

Overall Chemical Profile

Research studies on some Phragmites species revealed the presence of varied groups of phytochemicals that comprised nitrogenous compounds, flavonoids, phenolic acids, lignans, quinones, terpenoids, steroids, as well as fatty acids and their esters, among others. A total of 118 compounds have been reported so far, most of which have been described from P. communis.

Phragmites australis, a grass species of the Poaceae family, has promising therapeutic potential in traditional medicine. Its phytochemical composition varies depending on its geographical origin, genetic differences, and extraction methods.

Flavonoids

Up to 95, 104, 144, and 158 components have been preliminarily identified in the root, stem, leaf, and flower of Phragmites australis, respectively. The quantity of flavonoids occupied 9.5%, 22.1%, 32.7%, and 34.8% in root, stem, leaf, and flower, respectively, indicating that flavonoids may play an important role in the species. The corresponding verified flavonoid contents were 12.81 mg/g, 12.01 mg/g, 5.11 mg/g, and 3.24 mg/g in flower, leaf, stem, and root, respectively.

LC–MS analysis of a Libyan-sourced aqueous extract revealed high levels of various phenolic compounds, including rutin, quercetin, luteolin-7-O-glucoside, caffeic acid, apigenin-6-C-glucoside, protocatechuic acid, coumaric acid, and feruloyl derivatives.

Phenolic Acids and Coumarins

A total of 24 phenolic compounds, including 13 phenolic acids, 9 flavonoids, and 2 coumarins, have been identified as constituents in reed aqueous extracts. Phenolic acids found across Phragmites tissues include p-coumaric acid, vanillic acid, sinapic acid, syringic acid, caffeic acid, protocatechuic acid, and gallic acid. Gallic acid is a key compound found in the root exudates of reed, and has also been detected in other tissues including the leaves, flowers, and stems.

Alkaloids and Nitrogenous Compounds

Two new alkaloids, phranisines A–B, along with two known compounds — N-p-coumaroyl serotonin and N-p-coumaroyl-tryptamine — have been isolated from the roots of Phragmites australis. LC-QToF-MS/MS analysis of leaf extracts in both positive and negative ionization modes revealed the existence of thirty and eleven bioactive compounds, respectively, tentatively identified as alkaloids, flavonoids, indoles, glycosides, and quinolines.

Polysaccharides

Rhizoma phragmitis polysaccharides have been specifically highlighted in both traditional medicine preparations and modern pharmacological research. They have been investigated for their role in immunomodulation, hepatoprotection, and dermatological activity. The chemical constituents of Phragmitis Rhizoma include polysaccharides, flavonoids, steroids, anthraquinones, and alkaloids.

Polyphenolic Content

The polyphenolic and flavonoid contents of one studied aqueous extract (PAAE) were measured at 65.94 mg GAE/g and 22.7 mg AAE/g, respectively. In another study, the polyphenolic content of a leaf aqueous extract was found to be 39.17 ± 0.65 mg GAE/g total phenol, while the flavonoid content was 19.85 ± 2.64 mg QE/g, and proanthocyanin content was 119.65 ± 1.70 CE/g.

Other Compounds

The reported metabolites include nitrogenous compounds, flavonoids, phenolic acids and their esters, lignans, quinones, terpenoids, steroids, fatty acids and their esters, sulfurous compounds, and other miscellaneous compounds. The genus has also been noted as a host for diverse endophytic microorganisms whose secondary metabolites contribute additional bioactive molecules.

4. Pharmacology and Established Mechanisms of Action

Overview of Reported Pharmacological Properties

Various organic extracts of different organs of Phragmites plants have been reported to show a range of biological and pharmacological properties, such as analgesic, antidiabetic, antihyperlipidemic, anti-inflammatory, antimicrobial, antioxidant, antiproliferative, and hepatoprotective activities. Modern pharmacological studies have shown that Rhizoma phragmitis has antiviral, antioxidative, anti-inflammatory, analgesic, and hypoglycemic functions, lowers blood lipids, and protects the liver and kidney.

Anti-Inflammatory Mechanisms

A water-soluble crude extract of P. australis was shown in vitro to significantly inhibit lipopolysaccharide (LPS)-induced production of inflammatory mediators — nitric oxide (NO), reactive oxygen species (ROS), and the pro-inflammatory cytokines tumor necrosis factor-alpha (TNF-α) and interleukin-1β (IL-1β) in RAW264.7 macrophage cells. The inflammation-relevant signaling pathways Erk1/2, P38MAPK, C-Jun, and NF-κB activated by LPS could be dramatically inhibited by this extract. This in vitro work (conducted in a macrophage cell line) establishes a plausible molecular basis for the anti-inflammatory properties attributed to the plant, though human confirmation is absent.

Antioxidant Mechanisms

The antioxidant capacity of aqueous extracts has been assessed by DPPH (2,2-diphenyl-1-picrylhydrazyl) and FRAP (ferric reducing antioxidant power) assays. The presence of polyphenols, flavonoids, and phenolic acids — well-established free radical scavengers — is proposed as the underlying mechanism. Phytochemical screening has identified flavonoids, phenols, tannins, steroids, glycosides, and reduced sugars; pharmacological studies also indicate the plant has analgesic, antidiabetic, antihyperlipidemic, anti-inflammatory, antimicrobial, antioxidant, and hepatoprotective actions.

Antiviral Mechanisms

In vitro, a water-soluble crude extract of P. australis was shown to also remarkably inhibit bovine herpes virus type 1 (BoHV-1) replication in MDBK cells. In other work, the antimicrobial activity of aqueous extract was tested against four bacterial and two fungal species, and the antiviral activity was evaluated against HSV-1 and hepatitis A virus (HAV). All antiviral findings to date are from in vitro models.

5. Scientific Evidence by Area of Health Use

5.1 Respiratory Tract Infections

The most substantial body of clinical evidence for Phragmites concerns its use (primarily as part of TCM formulations) in acute respiratory tract infections (ARTIs).

Study type and design: Eight databases and two clinical trial registries were searched from inception to 8 February 2023 for randomized controlled trials (RCTs) evaluating any preparation involving P. communis without language restrictions, using the Risk of Bias Tool 2.0 to assess trial quality.

Results: Forty-two RCTs involving 6,879 patients with ARTIs were included. The results showed that P. communis preparations had significant efficacy in improving symptoms in patients with ARTIs, especially in febrile patients and patients with acute exacerbation of COPD (AECOPD).

Evidence quality and limitations: Low- or very low-certainty evidence suggests that P. communis preparations may improve the cure rate of ARTIs, shorten the fever clearance time in febrile patients, and improve the pulmonary function of patients with acute exacerbation of COPD or chronic bronchitis. However, these findings are inconclusive and need to be confirmed in further high-quality trials. A critical limitation is that the majority of included trials investigated P. communis as part of multiherb formulas rather than as a sole agent, making it impossible to isolate the specific contribution of Phragmites from the overall formula effect. The certainty of evidence was rated as low to very low.

5.2 Liver Protection (Hepatoprotective Activity)

Traditional basis: The rhizome of Phragmites australis has long been used for the treatment of hepatitis in traditional Chinese medicine.

Preclinical evidence: The hepatoprotective and antioxidant activities of an aqueous extract from the rhizome of P. australis (AE-PA) were evaluated. The acute toxicity test in mice showed that AE-PA was nontoxic since a dose of 2000 mg/kg body weight did not cause toxic symptoms or mortality. The prolongation of hexobarbital-induced sleeping time by carbon tetrachloride (CCl4) administration to mice was significantly reduced after pretreatment with AE-PA at 500 mg/kg b.w., proving the protective effect of the extract on microsomal drug-metabolizing enzyme. This is animal-model evidence only. No controlled human clinical trials specifically investigating Phragmites for hepatoprotection have been identified in the peer-reviewed literature.

5.3 Atopic Dermatitis and Skin

Animal/preclinical evidence: A study evaluated the topical effects of the polysaccharide-rich extract of P. rhizoma (PEP) on atopic dermatitis. AD-like skin lesions were induced by an extract of the house-dust mite Dermatophagoides farinae (Dfb) in NC/Nga mice. Topically applied PEP suppressed dermatitis with a decrease in dermatitis score and scratch number. The histological manifestations of atopic skin lesions, including thickened epidermis and increased numbers of mast cells, polymorphonuclear leukocytes, and nerve fibers, were significantly attenuated. These results indicated that PEP might have an inhibitory effect on atopic dermatitis-like lesions and could be a promising natural resource in the treatment of atopic dermatitis. This is animal-only evidence; no human trials have been reported.

5.4 Antidiabetic and Metabolic Effects

Preclinical evidence: Research with animal models of diabetes has examined Phragmites aqueous and polysaccharide extracts for effects on blood glucose, lipid metabolism, and pancreatic tissue. Modern pharmacological studies have shown that Rhizoma phragmitis has hypoglycemic functions and lowers blood lipids. In vitro work has also explored activation of peroxisome proliferator-activated receptors-γ (PPARγ) — a major target for insulin sensitization — as a possible mechanism. Evidence is confined to animal models and in vitro screens; no human clinical trials are available.

5.5 Antimicrobial Activity

In vitro evidence: The antimicrobial activity of aqueous extract has been tested against four bacterial and two fungal species. Endophytes isolated from the roots of P. australis have been shown to inhibit multi-drug resistant pathogens in laboratory conditions. All available antimicrobial evidence is in vitro. The clinical significance for human infectious disease management has not been established.

5.6 Antiviral Activity

In vitro and classical formulation evidence: During the Novel Coronavirus epidemic in 2020, Weijing Decoction and Wuye Lugen Decoction — with Rhizoma phragmitis as the main herbal component — were included in The Pneumonia Treatment Protocol for Novel Coronavirus Infection (Trial Version 5) due to reported antiviral effects. However, inclusion in a national clinical protocol does not itself constitute robust clinical trial evidence; this reflected expert consensus within TCM frameworks rather than placebo-controlled trial data. In vitro antiviral activity has been demonstrated against BoHV-1 and assessed against HSV-1 and HAV.

5.7 Analgesic Effects

Analgesic activity has been reported among the pharmacological properties of Phragmites extracts. Evidence is limited to preclinical (animal) studies. No human analgesic trials have been identified.

5.8 Antihyperlipidemic Effects

Various organic extracts of Phragmites have been reported to show antihyperlipidemic activities in experimental settings. These findings originate from animal studies and in vitro lipid assays. Human lipid-lowering trials are not available in the current literature.

6. Body Systems and Health Areas Associated with Phragmites

• Respiratory system: Used historically for fever, lung abscesses, cough, and thick phlegm; the most studied area in clinical research (TCM formulations for ARTIs and COPD exacerbations).
• Gastrointestinal system: Traditionally prescribed to relieve fever, vomiting, dysuria, and constipation. Anti-emetic and anti-diarrheal uses are documented across Chinese and Korean medicine.
• Hepatic system: Traditional use for hepatitis; preclinical hepatoprotective activity demonstrated in CCl4-induced liver injury models.
• Urinary system: Recommended historically for promoting diuresis. An animal study has also explored the prevention of calcium oxalate kidney stones.
• Metabolic/endocrine: Preclinical evidence of antidiabetic and antihyperlipidemic action.
• Skin/integumentary: Polysaccharide-rich rhizome extract studied for atopic dermatitis in animal models; moisturizing properties have also been investigated in cosmeceutical contexts.
• Immune system: Anti-inflammatory activity via NF-κB and MAPK pathway inhibition in vitro; possible immunomodulation via polysaccharides.

7. Dosage Forms and Dosages Reported in Studies

The following dosages and forms are reported directly from identified sources and should not be interpreted as clinical recommendations.

• Aqueous extract (animal hepatoprotection study): An acute toxicity test in mice used a dose of 2000 mg/kg body weight without toxic symptoms or mortality; a pretreatment dose of 500 mg/kg b.w. demonstrated protective effect on microsomal drug-metabolizing enzyme.
• Phragmitis rhizoma aqueous extract (pharmacokinetic interaction study in rats): The study investigated the effects of Phragmitis rhizoma aqueous extract (EPR) on the pharmacokinetics of docetaxel in Sprague-Dawley rats. Animals received an intravenous injection of docetaxel (5 mg/kg) with or without oral EPR (100 mg/kg) pretreatment for 1 or 6 days.
• Clinical trial formulations (ARTIs, human): Any oral preparation derived from the root of P. communis, whether used as monotherapy or as part of an herbal mixture, was included in the systematic review; no restrictions were imposed regarding dosage or treatment duration in that meta-analysis, reflecting the heterogeneity of dosing across the 42 included trials.
• TCM classical decoctions: In classical TCM usage, Rhizoma phragmitis is typically prescribed as a water decoction in amounts defined by pharmacopeial monographs, often used fresh in large amounts given its mild potency and broad safety margin — but the precise gram ranges vary by source and formulation and were not uniformly reported across identified studies.

8. Safety Considerations and Pharmacokinetic Interactions

General Toxicological Profile

The available toxicological data have suggested the safety of Phragmites species studied so far. A dedicated genotoxicity study demonstrated that aqueous extract of Phragmitis rhizoma is safe regarding genotoxicity in an experimental model at least under the conditions tested. The authors noted that further toxicity assessment in a human clinical study should be done to support the safe use of Phragmitis rhizoma by patients and healthcare providers.

One study's conclusion confirmed that aqueous extract of Phragmitis rhizoma is safe regarding genotoxicity in an experimental model. Preclinical acute toxicity studies have not identified lethal doses at high experimental doses in rodents, but systematic human safety data are not yet available.

Herb–Drug Interaction: Docetaxel

A previous study demonstrated that the Phragmitis rhizoma aqueous extract (EPR) ameliorates docetaxel (DTX)-induced myelotoxicity; a follow-up study was aimed to investigate the effects of EPR on the pharmacokinetics of DTX in Sprague-Dawley rats. Relative to the control group (DTX alone), EPR pretreatment did not significantly affect the overall profiles of plasma DTX levels, suggesting no major pharmacokinetic interaction at the doses tested in rats. However, this finding is from a rat study; human pharmacokinetic interaction data are absent.

The use of botanical dietary supplements has grown steadily despite incomplete information regarding active constituents, mechanisms of action, efficacy, and safety. This caution is directly applicable to Phragmites: while the plant is associated with a long history of use and a favorable preclinical safety profile, human pharmacokinetic and pharmacodynamic interaction studies are not yet available.

Phytochemical Variability

Phragmites australis has promising therapeutic potential in traditional medicine; however, its phytochemical composition varies depending on its geographical origin, genetic differences, and extraction methods. This variability is a significant practical concern for standardization of any supplement product derived from the plant.

Evidence Gaps and Research Limitations

Despite promising findings, clinical research on the efficacy of Phragmites in humans remains limited. Few well-designed human studies have been conducted, and most available evidence is preclinical. While the traditional use and early scientific results are encouraging, more rigorous clinical trials are needed to validate its health benefits and establish effective dosages and safety profiles in nutritional products.

Few studies have rigorously investigated the phytochemical components, properties, and potential biological benefits of Phragmites australis as an emergent macrophyte. The most significant body of clinical data relates to TCM multi-herb formulations rather than Phragmites as a single ingredient, and the overall evidence certainty from the largest systematic review is rated as low to very low.

References

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