Lian Qiao
StarForsythia suspensa (Thunb.) Vahl
Traditionally used for
- Headaches
- Nose & throat
- Colds & fever
- Urinary & fluids
- Skin
☯ TCM Properties
Clears Heat and Resolves Toxicity; Disperses Swelling and Dissipates Nodules; Disperses Wind-Heat; Clears Heart Fire; Promotes Urination
Traditional Chinese Uses
Lian Qiao (forsythia fruit) is a cool, bitter herb classified among the primary herbs for clearing Heat toxin and resolving toxic swellings. It is used extensively for Wind-Heat exterior patterns with fever, sore throat, and headache, and for the inflammation and suppuration of carbuncles, furunculosis, and lymphadenitis. Known as "the holy herb for sores," it is featured in the famous formula Yin Qiao San for the common cold and early-stage febrile illness.
Western Herbalism Properties
Used In Formulas (11)
Relationships
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Botanical Description
Forsythia suspensa is a deciduous, arching to weeping shrub in the family Oleaceae, native to mountain valleys, scrublands, and forest margins of central and eastern China and now widely cultivated as an ornamental across temperate regions. The plant grows 1-3 m tall, producing long, slender, hollow or chambered branches that arch outward and often root where they touch the ground. The opposite leaves are ovate to lanceolate, 3-10 cm long, simple or sometimes trifoliolate on vigorous shoots, with serrate margins and a pointed apex. Bright yellow, bell-shaped flowers 2-3 cm across appear in clusters along the bare branches in early spring before the leaves expand, each with a deeply four-lobed corolla. The fruit is a brown, ovoid, beaked, woody dehiscent capsule about 1.5-2 cm long, splitting into two valves to release flat winged seeds. The dried fruits, collected when ripe, are the medicinal part.
Active Constituents
Forsythoside A (forsythiaside A)
Phenylethanoid glycosideConcentration: The marker compound the Chinese Pharmacopoeia uses for the drug. HPLC surveys report roughly 0.33-0.76% of ripe fruit (Lao Qiao) and 0.85-1.56% of unripe fruit (Qing Qiao); other batch series of unripe fruit have assayed 3.87-8.72%, and material from six origins spanned 14.06-88.00 mg/g, so batch variation is very wide.
The dominant phenylethanoid glycoside of the fruit and one of the two constituents on which the drug's official assay rests. It carries much of the anti-inflammatory, antioxidant and anti-influenza activity attributed to Forsythiae Fructus, with reported inhibition of TLR7, RIG-I, MAVS, MyD88 and NF-kB signalling. Oral bioavailability is low, which is a recognised gap between the in vitro potency and the clinical dose.
Phillyrin (forsythin)
Lignan glycosideConcentration: The Chinese Pharmacopoeia 2020 sets a minimum of 0.15% on the dried drug. Measured values range from 0.57-2.50% in ripe fruit and 0.73-2.16% in unripe fruit; across ten growing areas, 0.72-3.54 mg/g. Leaves are richer than fruit (about 2.6% in leaves versus 0.91% in unripe and 0.17% in ripe fruit).
A lignan glucoside and the second official assay marker. It is anti-inflammatory and antiviral in cell and animal models and is a cyclic-AMP phosphodiesterase-4 inhibitor. In rats it induced CYP1A2 and CYP2D1 activity, which is the basis of the interaction cautions below.
Phillygenin
Lignan (aglycone of phillyrin)Concentration: Higher in ripe fruit than unripe fruit: average 0.9258 mg/g in ripe versus 0.4873 mg/g in unripe fruit in one three-batch comparison.
The deglycosylated form of phillyrin and one of the compounds actually circulating after oral dosing, since phillyrin is extensively hydrolysed. It is one of the five lignans and phenylethanoids summed in the total-content specification used for the fruit.
Pinoresinol and pinoresinol beta-D-glucoside
Furofuran lignan and its glucosideConcentration: Pinoresinol beta-D-glucoside is reported at 0.3-2% in the leaves; fruit levels are lower.
Furofuran lignans that contribute to the antioxidant and anti-inflammatory profile of the drug. Pinoresinol is one of the five compounds summed in the total lignan and phenylethanoid specification.
Rutin
Flavonol glycosideConcentration: 0.05-0.36% of unripe fruit depending on harvest date, peaking in early July; 2.03 mg/g in one whole-drug assay. Ripe fruit is markedly lower.
The principal flavonoid of the fruit and one reason unripe Qing Qiao tests as more antioxidant than ripe Lao Qiao. Total flavonoids run about 1.36% in unripe and 1.10% in ripe fruit.
Forsythia essential oil (beta-pinene-rich volatile fraction)
Monoterpene-rich volatile oilConcentration: Not standardised in the Pharmacopoeia; composition varies with origin and extraction method.
The volatile fraction is directly antibacterial, altering bacterial membrane permeability and integrity so that nucleic acids and protein leak out, with reported MIC values of 3.13 mg/mL against Escherichia coli and 1.56 mg/mL against Staphylococcus aureus. beta-Pinene is among the more active components.
⚠ Drug Interactions
CYP1A2 substrates (e.g. theophylline, clozapine, olanzapine, tizanidine, caffeine)
In rats given a cocktail of probe drugs, both phillyrin and forsythoside A altered caffeine pharmacokinetics, and in rat liver microsomes each raised acetaminophen formation from phenacetin (the CYP1A2 probe) by 208% and 223% respectively over control. The authors concluded that both compounds have inductive effects on CYP1A2. This is rodent CYP1A2 only; there is no human pharmacokinetic study of Forsythiae Fructus.
Clinical note: Treat as unquantified rather than proven. If a patient on theophylline, clozapine or tizanidine takes a Forsythia-containing formula such as Yin Qiao San or Shuang Huang Lian for more than a few days, monitor for reduced drug effect and check levels where routine monitoring exists.
CYP2D6 substrates (e.g. metoprolol, dextromethorphan, tamoxifen, codeine)
Phillyrin pretreatment significantly changed metoprolol pharmacokinetics in rats and raised microsomal dextrorphan formation from dextromethorphan by 125% over control, indicating induction of rat CYP2D1, the rodent analogue of human CYP2D6. Forsythoside A did not affect this pathway. Rodent CYP2D1 and human CYP2D6 are not interchangeable, and human CYP2D6 is not readily inducible, so extrapolation is weak.
Clinical note: No action needed for short courses. For prodrugs that depend on CYP2D6 activation, such as codeine and tamoxifen, prefer not to layer a lignan-rich Forsythia extract on top of long-term therapy without review.
CYP2C9 substrates (e.g. warfarin, tolbutamide, phenytoin, NSAIDs)
Forsythoside A pretreatment significantly affected tolbutamide pharmacokinetics in rats and raised microsomal 4-hydroxytolbutamide formation by 154% over control, consistent with induction of rat CYP2C11. Phillyrin did not. Neither compound affected CYP3A1/2. Again this is an animal finding with no human confirmation.
Clinical note: For a patient on warfarin, check the INR about a week after starting or stopping a Forsythia-containing formula rather than assuming no effect.
Dosage
| Form | Amount | Frequency | Duration | Population | Notes |
|---|---|---|---|---|---|
| decoction | 6–15 g | Daily | — | — | 中国药典 2020 【用法与用量】6～15g。 【性味与归经】苦，微寒。归肺、心、小肠经。 — Chinese Pharmacopoeia 2020, quoted verbatim; route and cautions preserved. Replaces a cleared category-filler value. |
Dui Yao — Herb Pairs
The classical two-herb combinations this herb appears in, each with an action neither herb has alone.
Together they vent wind-heat from the exterior while clearing heat and toxin, covering both the surface and the toxic-heat aspect of early warm-febrile disease.
Classic for the initial wei-level stage of warm disease with fever, sore throat and thirst; also used together for hot sores and swellings.
Core pair of a classical formula — Yin Qiao San, Wen Bing Tiao Bian (Wu Jutang)
Evidence Tier
Strong evidence · 2 studiesRecorded studies by study design, strongest design at the top. This is a study-design tier only, not a GRADE rating: it does not weigh risk of bias, consistency or precision.
Systematic review / meta-analysis
1
1 verified · 0 unverified
Randomized controlled trial
0
Other clinical trial
0
Observational / case report
0
In vitro / animal
1
1 verified · 0 unverified
Other / unclassified
0
Verified: design read from PubMed for a DOI that resolves to the cited paper Unverified: taken from the study's recorded description
Clinical Studies
Effects of phillyrin and forsythoside A on rat cytochrome P450 activities in vivo and in vitro
A cocktail probe study in rats and in rat liver microsomes, testing the two Pharmacopoeia marker compounds of Forsythiae Fructus against CYP1A2, CYP2C11, CYP2D1 and CYP3A1/2. Phillyrin induced CYP1A2 and CYP2D1 without affecting CYP2C11 or CYP3A1/2; forsythoside A induced CYP1A2 and CYP2C11 without affecting CYP2D1 or CYP3A1/2. This is the main experimental basis for expecting metabolic interactions with the herb, and it is animal-only.
The phytochemistry, pharmacology, pharmacokinetics, quality control, and toxicity of Forsythiae Fructus: An updated systematic review
Catalogues 290 compounds from Forsythia suspensa, 248 of them from the fruit, including 42 phenylethanoid glycosides, 48 lignans, 59 terpenoids and 14 flavonoids. Identifies TLR7, RIG-I, MAVS, NF-kB and MyD88 inhibition as the reported anti-influenza mechanisms, with phenylethanoid glycosides and lignans as the active groups. It records that in vivo bioavailability of both groups is low, that official quality control still rests only on forsythoside A and phillyrin, and that no toxicity of the fruit has been reported to date.
Historical Texts
Shen Nong Ben Cao Jing
Han dynastyChinese Pharmacopoeia (Zhonghua Renmin Gongheguo Yaodian)
Modern, 2020 editionReferences
- Wang Z, Xia Q, Liu X, Liu W, Huang W, Mei X, Luo J, Shan M, Lin R, Zou D, Ma Z. Phytochemistry, pharmacology, quality control and future research of Forsythia suspensa (Thunb.) Vahl: A review . Journal of Ethnopharmacology (2018) [DOI]
- Dong Z, Lu X, Tong X, Dong Y, Tang L, Liu M. Forsythiae Fructus: A Review on its Phytochemistry, Quality Control, Pharmacology and Pharmacokinetics . Molecules (2017) [DOI]
- Zhou C, Lu M, Cheng J, Rohani ER, Hamezah HS, Han R, Tong X. Review on the Pharmacological Properties of Phillyrin . Molecules (2022) [DOI]
- Yang YD, Chen ZH, Li JJ, Yang X, Shi W, Liang H, Zhang FX. Traditional Chinese medicine preparation Shuang-Huang-Lian in the treatment of influenza: A review . Journal of Ethnopharmacology (2025) [DOI]
This information is for educational purposes only and is not intended to replace professional medical advice. Always consult a qualified healthcare provider before using any herbal remedy, especially if you are pregnant, nursing, or taking medications.
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