Bai Guo
StarGinkgo biloba L.
Traditionally used for
- Cough & breathing
- Urinary & fluids
- Menstrual & women's health
- Energy & fatigue
Cautions & contraindications
- Young children
- Bleeding disorders
- Seizure disorders
- Toxic — professional use only
☯ TCM Properties
Astringes the Lungs and calms wheezing; Expels Phlegm; Astringes to Stop Vaginal Discharge; Secures Essence and Stops Enuresis
Traditional Chinese Uses
Bai Guo (ginkgo seed, ginkgo nut) is a neutral, slightly toxic herb used in Chinese medicine to astringe the Lung and stop leakage from Kidney deficiency. Its astringent action addresses chronic cough, wheezing, and copious phlegm from Lung deficiency, as well as excessive vaginal discharge and urinary incontinence from Kidney deficiency. Because it has mild toxicity, it is used in limited quantities and never eaten in large amounts raw. Its calming action on the Lung makes it a classical ingredient in asthma and cough formulas.
Western Herbalism Properties
Relationships
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Botanical Description
Ginkgo biloba is a long-lived deciduous tree in the monotypic family Ginkgoaceae, often growing 20 to 35 meters tall, with a strongly pyramidal crown when young that broadens with age. The bark is grey, becoming deeply fissured on old trunks, and shoots are dimorphic, with long shoots bearing scattered leaves and short spur shoots producing dense clusters. Leaves are unique among seed plants: fan-shaped, leathery, 5 to 10 cm wide, with dichotomously branching veins and a notch dividing the blade into two lobes. The species is dioecious; male trees bear small catkin-like pollen cones while female trees produce paired ovules on slender stalks that mature into fleshy, plum-like seeds with a foul-smelling fleshy outer coat and a hard inner shell enclosing the edible kernel. Native to a small area of central China and surviving as a relict of an ancient lineage, Ginkgo is now widely cultivated worldwide as an ornamental and medicinal tree.
Active Constituents
Ginkgotoxin (4'-O-methylpyridoxine, MPN)
Pyridoxine (vitamin B6) analogue, pyridine alkaloidConcentration: Present in both the kernel and the exotesta of the seed; in raw seed most of it is stored as the 5'-glucoside rather than as free MPN, and free MPN rises during heating and during aqueous extraction as endogenous glucosidases hydrolyse the glucoside
This is the convulsant principle of the ginkgo seed and the single most important reason Bai Guo is dose-limited. It is an antivitamin B6: it is accepted by human pyridoxal kinase as an alternate substrate with a lower Km than pyridoxal, pyridoxamine or pyridoxine, so it competitively starves the cell of pyridoxal-5'-phosphate, the cofactor glutamate decarboxylase needs to make GABA. The result is vomiting followed by generalised tonic-clonic seizures, reversible with pyridoxal phosphate. Note that ginkgotoxin occurs in the leaf as well, but it is the seed that is eaten in quantity.
Ginkgotoxin-5'-glucoside (4'-O-methylpyridoxine-5'-glucoside, MPNG)
Pyridoxine analogue glucosideConcentration: The predominant form of ginkgotoxin in raw seed; measured native contents of MPNG exceed those of MPN in both the exotesta and the kernel across cultivars
The storage form of the toxin. It is hydrolysed to free MPN by the seed's own glucosidases and by heat treatment, so a simple 'measured MPN' figure on a raw seed understates the total convulsant load a patient actually receives. Cooking reduces but does not abolish ginkgotoxin, which is why roasted seeds have still caused seizures.
Ginkgolic acids
Alkylphenolic acids (anacardic acid type)Concentration: Concentrated in the fleshy outer sarcotesta and seed coat rather than the kernel
Cytotoxic and strongly sensitising; they are the reason handling the fallen fleshy seed coat causes a urushiol-like contact dermatitis. Standardised ginkgo leaf extracts for oral use are deliberately depleted of ginkgolic acids to a few parts per million; the culinary and medicinal seed is subject to no such limit, so this is a seed-specific hazard that the leaf-extract safety literature does not cover.
Allergenic glycoprotein of the seed
GlycoproteinA distinct seed constituent from ginkgotoxin, reported to cause nausea, vomiting, dyspnoea, mydriasis and abdominal pain. It contributes to the picture of acute ginkgo seed poisoning independently of the vitamin B6 mechanism.
Amygdalin-derived hydrocyanic acid
Cyanogenic glycoside and its released cyanideReported among the toxins of the fresh seed, contributing dizziness, vomiting, cramping and disturbed sleep. It is one of the five seed toxins that food-processing research specifically targets for removal, alongside ginkgotoxin, its glucoside, ginkgolic acid and the allergenic glycoprotein.
Starch, storage lipid and seed protein
Nutritional macronutrientsThe bulk of the kernel. Bai Guo is a starchy food as much as a medicine, which is exactly why overconsumption at a meal, rather than at a therapeutic dose, is the usual route to poisoning.
⚠ Drug Interactions
Vitamin B6-depleting drugs (isoniazid, cycloserine, hydralazine, penicillamine)
Ginkgotoxin from the seed is an alternate substrate for human pyridoxal kinase and lowers pyridoxal-5'-phosphate; isoniazid and the other listed drugs deplete the same cofactor by hydrazone formation or by inhibiting the kinase. The two mechanisms converge on the same pool. Human case data show serum and CSF pyridoxal-5'-phosphate falling and the PLP-to-pyridoxal ratio collapsing during ginkgo seed poisoning.
Clinical note: Do not prescribe Bai Guo to a patient on isoniazid or any other B6-antagonist drug. If seed poisoning is suspected, the treatment is parenteral or oral pyridoxal phosphate, which has resolved seizures in published cases at 2 mg/kg intravenously in a child and 400 mg orally in an adult.
Anticonvulsants and any regimen in a patient with epilepsy (valproate, levetiracetam, carbamazepine)
The seed's convulsant action is pharmacodynamic and works upstream of the anticonvulsants, by reducing GABA synthesis rather than by altering drug levels. Published poisonings occurred in people with no epilepsy at all, at 20-30 seeds in a 2-year-old, 50 roasted seeds in a 64-year-old and about 80 fried seeds in a 48-year-old, so a patient with an already low threshold has no margin.
Clinical note: Treat Bai Guo as contraindicated in epilepsy and in children. Warn every patient given Bai Guo that the seed is a food they must not eat freely alongside the prescription, and that vomiting followed by twitching is the warning sign.
Alcohol
In the published adult case of 50 roasted seeds taken with 100 g of alcohol, vomiting and tonic-clonic convulsions did not appear until 9.5 hours after ingestion, and the authors concluded the alcohol probably extended the latent period. Untreated poisonings otherwise declare themselves in roughly 6-9 hours.
Clinical note: Seeds eaten as a drinking snack are the classic adult presentation. A long symptom-free interval after a large seed meal does not mean the patient is out of danger.
Standardised Ginkgo biloba leaf extract supplements (EGb 761 and equivalents)
Ginkgotoxin occurs in the leaf as well as the seed, and some manufacturers specifically reduce 4'-O-methylpyridoxine in leaf extract for that reason. A patient taking a cognition supplement is very likely to describe it simply as 'ginkgo' and not to connect it with the Bai Guo in a cough prescription, although the two are different drugs with different indications and different chemistry.
Clinical note: Ask specifically whether the patient is already taking a ginkgo leaf supplement before prescribing Bai Guo, and record which part of the plant each product is.
Warfarin, aspirin, clopidogrel and other antiplatelet or anticoagulant drugs
The widely repeated ginkgo bleeding interaction rests on the platelet-activating-factor antagonism of the ginkgolides in standardised LEAF extract (EGb 761), which is a concentrated, terpene-lactone-standardised preparation. Bai Guo is the seed and is not a standardised source of terpene trilactones, so the leaf data should not simply be transferred to it. It should not be dismissed either, because patients and pharmacists reading only the genus name will apply the leaf warning to the seed.
Clinical note: Do not tell a patient on warfarin that 'ginkgo interacts' without establishing which ginkgo drug is in front of you. Record the plant part on the prescription so a later reviewer is not left guessing.
Urushiol cross-reactive exposures (poison ivy and poison oak, cashew nut shell, mango skin)
The alkylphenolic ginkgolic acids of the seed coat are structurally the same class of long-chain phenol as urushiol and anacardic acid, and they are cytotoxic and allergenic. Handling the fleshy sarcotesta while preparing raw seed is the usual exposure.
Clinical note: Warn patients and dispensary staff to handle raw seed with gloves, and be cautious in anyone with a history of poison ivy or cashew reactions.
Dosage
| Form | Amount | Frequency | Duration | Population | Notes |
|---|---|---|---|---|---|
| decoction | 5–10 g | — | — | — | ChP 2025. 生食有毒 — the raw seed is toxic; children are markedly more susceptible. Corrected from a generic 6-15g decoction filler value generated from tcm_category. |
Dui Yao — Herb Pairs
The classical two-herb combinations this herb appears in, each with an action neither herb has alone.
Dispersing and opening the Lung combined with astringing Lung qi, the pair calms wheezing without the dispersal exhausting the Lung or the astringency trapping the pathogen.
Wheezing with phlegm-heat and an exterior wind-cold constraint. Bai Guo is toxic raw or in excess.
Core pair of a classical formula — Ding Chuan Tang, She Sheng Zhong Miao Fang (Zhang Shiche)
Evidence Tier
Moderate evidence · 6 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
0
Randomized controlled trial
0
Other clinical trial
0
Observational / case report
4
4 verified · 0 unverified
In vitro / animal
2
0 verified · 2 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
Ginkgo Seed Poisoning
A 2-year-old girl who ate a large quantity of ginkgo seeds vomited and had diarrhoea at 7 hours and an afebrile convulsion at 9 hours, with a serum 4-methoxypyridoxine concentration of 360 ng/mL. Pyridoxal phosphate 2 mg/kg appears to have prevented further seizures. The authors note that reported cases usually involve children and that repetitive seizures in that group can be fatal. This is a study of the SEED, not of leaf extract.
An Adult Case of Generalized Convulsions Caused by the Ingestion of Ginkgo biloba Seeds with Alcohol
A 64-year-old woman vomited and had tonic-clonic convulsions 9.5 hours after eating 50 roasted Ginkgo biloba seeds with 100 g of alcohol; intravenous pyridoxal phosphate resolved the symptoms. Serial sampling over 35 hours showed high 4'-O-methylpyridoxine and high total B6 vitamers but low pyridoxal phosphate during the acute phase, confirming that the toxin blocks conversion to the active cofactor rather than causing simple B6 deficiency. The authors suggest the alcohol lengthened the latency.
Epileptic Seizure from Ginkgo Nut Intoxication in an Adult
A 48-year-old man who ate roughly 80 fried ginkgo seeds as a bar snack developed repeated generalised tonic-clonic seizures about 6 hours later, with vomiting, vertigo, diarrhoea and upper-limb tremor. 4-O-methylpyridoxine was 312 ng/mL and pyridoxal phosphate was low at 2.4 µg/L. Oral pyridoxal phosphate 400 mg resolved the episode with no recurrence.
Concentrations of various forms of vitamin B6 in ginkgo seed poisoning
A 2-year-old girl had repetitive tonic-clonic convulsions after eating 20-30 ginkgo seeds. The authors measured pyridoxal-5'-phosphate, pyridoxal, 4-pyridoxic acid and 4'-O-methylpyridoxine in both serum and cerebrospinal fluid, and found high MPN in both compartments with a markedly reduced PLP-to-pyridoxal ratio, which they argue is the parameter that matters for GABA synthesis. This is the clearest human demonstration that the seed toxin crosses into the CSF.
The human pyridoxal kinase, a plausible target for ginkgotoxin from Ginkgo biloba
Using recombinant homogeneous human pyridoxal kinase, ginkgotoxin was shown to act as an alternate substrate with a lower Km than pyridoxal, pyridoxamine or pyridoxine, so its presence temporarily reduces pyridoxal phosphate formation. This is the mechanistic underpinning of the clinical picture, and the authors explicitly discuss it in relation to ginkgo products used as nootropics as well as to the seed.
4′-O-methylpyridoxine: Preparation from Ginkgo biloba Seeds and Cytotoxicity in GES-1 Cells
MPN extracted from Ginkgo biloba seeds (yield 1.933 µg/mg under the optimised conditions) inhibited proliferation of human gastric epithelial GES-1 cells with an IC50 of 127.80 µM, arrested the cell cycle in G2 and produced 43.80% apoptotic cells at 100 µM, with loss of mitochondrial membrane potential and raised caspase 8 and Bax. It indicates a direct cytotoxicity of the seed toxin on gastric epithelium in addition to its neurological action.
⚠ Safety & Contraindications
- Young children
- Bleeding disorders
- Seizure disorders
- Toxic — professional use only
Contraindications
Use with caution in children. Not for prolonged use or in large amounts.
Safety Warnings
- Children are much more susceptible; the number of seeds matters and paediatric poisonings are the majority of reported cases.
- Always cooked before use; the raw seed is more toxic.
- Distinct from Ginkgo leaf extract (Yin Xing Ye), which has a different profile.
⚠ Toxicity Information
Vomiting, irritability and, characteristically, convulsions from pyridoxine antagonism — reported chiefly in children after eating quantities of the roasted seed.
Historical Texts
Shaoxing Ben Cao
Song dynastyBen Cao Gang Mu
Ming dynasty (1596)References
- Liu Y, Xin H, Zhang Y, Che F, Shen N, Cui Y. Leaves, seeds and exocarp of Ginkgo biloba L. (Ginkgoaceae): A Comprehensive Review of Traditional Uses, phytochemistry, pharmacology, resource utilization and toxicity . Journal of Ethnopharmacology (2022) [DOI]
- Boateng ID. A critical review of current technologies used to reduce ginkgotoxin, ginkgotoxin-5′-glucoside, ginkgolic acid, allergic glycoprotein, and cyanide in Ginkgo biloba L. seed . Food Chemistry (2022) [DOI]
- Kobayashi D. Food Poisoning by Ginkgo Seeds through Vitamin B6 Depletion . YAKUGAKU ZASSHI (2019) [DOI]
- Zhang W, Shi M, Wang J, Cao F, Su E. A comprehensive review of ginkgotoxin and ginkgotoxin-5′-glucoside in Ginkgo biloba L. seeds . Journal of Food Composition and Analysis (2024) [DOI]
- Zhang W, Shi M, Zhang F, Cao F, Su E. A Facile Method to Determine the Native Contents of 4′-O-Methylpyridoxine and 4′-O-Methylpyridoxine-5′-glucoside in Ginkgo biloba Seeds . Journal of Agricultural and Food Chemistry (2021) [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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