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Lily of the valley
Toxic🐾Maiglöckchen · (Convallaria majalis)
Asparagus family (Asparagaceae)
Description
The sweet scent of its small, bell-shaped white flowers makes lily of the valley one of Europe's most recognisable woodland-floor plants each May. A member of the asparagus family, it spreads by underground runners through shady deciduous woods. Its leaves and flowers contain cardiac glycosides, principally convallatoxin. An earlier Commission E monograph described standardised preparations for mild heart weakness, before more precisely dosable Digitalis medicines largely replaced them; homeopathy still uses the plant today in highly diluted form. Outside these tightly controlled applications, lily of the valley is highly toxic: even small amounts — including the water from a vase of cut flowers — can trigger dangerous cardiac arrhythmias in people and pets alike. Preparing anything from the fresh plant at home is strongly discouraged.
🌿 Risk of confusion — read before wild-harvesting!
Lily of the valley (Convallaria majalis) contains cardenolide cardiac glycosides (convallatoxin, convalloside, convallatoxol) that can cause life-threatening cardiac arrhythmias, AV block, and ventricular fibrillation when overdosed.
External use only!
This plant must NOT be taken internally. Use only as compress, salve, or bath.
CONTRAINDICATED during pregnancy
Cardiac glycosides cross the placental barrier and can cause foetal cardiac arrhythmias. Any internal use during pregnancy is strictly contraindicated.
CONTRAINDICATED during breastfeeding
Cardiac glycosides can pass into breast milk and cause cardiotoxic effects in the infant. Internal use during lactation is strictly contraindicated.
CONTRAINDICATED for children
Children are particularly at risk of poisoning due to lower body mass and more sensitive cardiac physiology. Any internal contact with plant parts must be strictly avoided in children. First aid: contact a poison control centre.
Critical drug interactions with:
Herzglykoside (Digitalis, Digoxin, Digitoxin) · Kaliumverlust-Diuretika (Thiazide, Schleifendiuretika) · Antiarrhythmika (Chinidin, Amiodaron, Verapamil)
Historically, lily of the valley flower oil and extract was rubbed topically for joint pain and gout. This external folk use was widespread in Northern Europe. Despite low dermal absorption, there is also a theoretical poisoning risk externally with large-area application on damaged skin.
Historical documentation only — do NOT use
These internal applications are historically documented. This plant is highly toxic — self-treatment can cause severe poisoning or death. For documentation only, explicitly NOT a recommendation.
The German Commission E issued a positive monograph in 1984 for Convallaria glycosides in mild cardiac insufficiency (NYHA I–II) and cardiac arrhythmias. Convallatoxin and convalloside inhibit Na⁺/K⁺-ATPase of cardiac muscle cells and increase contractile force (positive inotropic). Today largely replaced by Digitalis glycosides; of historical-pharmaceutical significance.
In traditional European medicine of the 16th–19th centuries, lily of the valley tincture from flowers and leaves was used as a cardiac remedy for oedema, dropsy, and heart weakness. Leonhart Fuchs described its use in his herbal of 1543. Before the advent of standardised Digitalis preparations, Convallaria was a widely used cardiac tonic.
In the folk medicine of Central and Eastern Europe, lily of the valley leaf tea was prepared for heart palpitations and dizziness. Due to the narrow therapeutic index of cardiac glycosides, folk users substantially underestimated the poisoning risk. Historical use without modern dosage control.
Homoeopathic preparations of Convallaria majalis (mother tincture D1–D30) are used in homoeopathy for cardiac arrhythmias, angina pectoris, and oedema. Homoeopathic use is based on the principle of similars — highly diluted preparations are considered safe. Outside the homoeopathic framework, the plant is highly toxic.
In Russian and Scandinavian folk medicine, lily of the valley extract was used for exhaustion, neurasthenia, and functional cardiac complaints. Russian pharmacopoeias of the early 20th century contained Convallaria preparations as official medicines. The weak evidence base differs markedly from the well-documented cardiac effect.
⚠ External use only
HIGHLY TOXIC — all parts of the plant are poisonous. Lily of the valley (Convallaria majalis) contains cardenolide cardiac glycosides (convallatoxin, convalloside, convallatoxol) that can cause life-threatening cardiac arrhythmias, AV block, and ventricular fibrillation when overdosed. Even small amounts — including flower water — can cause poisoning. Poisoning signs: nausea, vomiting, bradycardia, visual disturbances (xanthopsia), loss of consciousness. In suspected poisoning, contact a poison control centre immediately. No self-medication with plant material. ASPCA classification (accessed 2026-08-10): toxic to dogs and cats.
Cardiac glycosides cross the placental barrier and can cause foetal cardiac arrhythmias. Any internal use during pregnancy is strictly contraindicated.
Cardiac glycosides can pass into breast milk and cause cardiotoxic effects in the infant. Internal use during lactation is strictly contraindicated.
Children are particularly at risk of poisoning due to lower body mass and more sensitive cardiac physiology. Any internal contact with plant parts must be strictly avoided in children. First aid: contact a poison control centre.
Drug interactions
Herzglykoside (Digitalis, Digoxin, Digitoxin)
Additive inhibition of Na⁺/K⁺-ATPase → cumulative cardiotoxicity with increased risk of AV block, bradycardia, and ventricular arrhythmias.
Kaliumverlust-Diuretika (Thiazide, Schleifendiuretika)
Diuretic-induced hypokalaemia substantially increases cardiac glycoside sensitivity — poisoning risk even at otherwise tolerated doses.
Antiarrhythmika (Chinidin, Amiodaron, Verapamil)
Pharmacokinetic and pharmacodynamic interactions can increase glycoside plasma levels or add cardiac effects.
Kortikosteroide (systemisch)
Systemic corticosteroids can cause hypokalaemia and thereby potentiate glycoside cardiotoxicity.
Contraindications
- Concurrent therapy with Digitalis glycosides (additive cardiotoxicity, risk of accumulation)
- Hypokalaemia (increases cardiac muscle cell sensitivity to cardiac glycosides)
- AV block grade II and III (cardiac glycosides slow AV conduction)
- Wolff-Parkinson-White syndrome and other accessory conduction pathways
- Hypertrophic obstructive cardiomyopathy (HOCM)
- Pregnancy and lactation
- Children under 18 years (all internal uses)
- Renal insufficiency (delayed excretion of glycosides)
Harvested part: flowering herb
- Time of day:
- Morning in dry weather, when flowers are fully open
- Drying:
- Lay flower panicles flat and dry at max. 35 °C in the shade. CAUTION: Toxic plant — wear protective gloves, do not put plant parts in mouth. Store dried material safely, out of reach of children and pets.
- Storage:
- 12 months — In sealed, labelled containers, dry and dark. Store separately from food and unlabelled herbs — risk of confusion!
- Time of day:
- Morning after dew has dried — young leaves have the highest glycoside content
- Drying:
- Lay leaves loosely, dry at 35–40 °C. Wear protective gloves without fail — glycoside absorption via skin cuts is possible. No contact with mucous membranes. Toxicity is fully retained in dried material.
- Storage:
- 12 months — Dry, dark, childproof. Clearly label as TOXIC.
- ConvallatoxinGlycosideContent: 0,1–0,3 %Aerial parts
Most important cardenolide cardiac glycoside of lily of the valley; inhibits Na⁺/K⁺-ATPase and raises intracellular calcium → positive inotropic. Extremely narrow therapeutic index; LD50 rat (i.v.) approx. 0.08 mg/kg.
- ConvallosidGlycosideAerial parts
Rhamnoside of strophanthidin; second most abundant cardiac glycoside; similar mechanism of action to convallatoxin, slightly less potent.
- ConvallatoxolGlycosideAerial parts
Dihydro derivative of convallatoxin; also cardioactive, but less extensively studied pharmacologically.
- LokundiosidGlycosideAerial parts
Further cardenolide glycoside; contributes to the overall toxicity of the plant.
- ConvallamarinGlycosideAerial parts
Historically described glycoside; less specifically cardioactive than convallatoxin; formerly described as a component of Convallaria extracts.
- Saponine (Convallamarosid, Diosgenin-Glykoside)SaponinWhole plant
Steroidal saponins from Convallaria majalis; haemolytic at high concentrations; partly responsible for gastrointestinal poisoning signs (nausea, vomiting).
- Flavonoide (Kaempferol, Quercetin-Glykoside)FlavonoidLeaf
Antioxidant flavonoid glycosides; pharmacologically less significant than the cardiac glycosides; not responsible for toxicity.
- AsparaginOtherAerial parts
Amino acid; detected in fresh leaves and rhizomes; contributes to the historical naming of the plant family Asparagaceae.
- [1]MonographBlumenthal M. et al. (eds., 1998): The Complete German Commission E Monographs — Convallaria herb. American Botanical Council, Austin TX(accessed: 2026-05-24)
- [5]MonographASPCA Animal Poison Control — Lily of the Valley (Convallaria majalis)(accessed: 2026-08-10)
- [6]MonographCliniTox Giftpflanzen — Convallaria majalis L.: stark giftig ++ (Institut für Veterinärpharmakologie und -toxikologie, Universität Zürich)(accessed: 2026-08-10)
- [4]BookPlants For A Future (PFAF): Convallaria majalis — Lily of the valley(accessed: 2026-05-24)
- [2]WikipediaWikipedia DE: Maiglöckchen (Convallaria majalis)(accessed: 2026-05-24)
- [3]WikipediaWikipedia EN: Convallaria majalis — Lily of the valley(accessed: 2026-05-24)