Ledum Marsh (Rhododendron tomentosum): Benefits, Dosage, Safety & Evidence

Questions fréquentes

How does Ledum marsh work as an expectorant?

Ledum marsh contains volatile compounds including ledol, palustrol, and ledene, which are believed to stimulate respiratory secretions. These constituents may irritate bronchial mucosa mildly, promoting mucus clearance. The herb also contains flavonoids with potential anti-inflammatory properties. However, evidence for these mechanisms remains theoretical and based on phytochemical analysis rather than clinical trials (Evidence Level C). Traditional use in Scandinavian folk medicine supports its expectorant application, but modern pharmacological studies are limited.

Can I take Ledum marsh with prescription medications?

Ledum marsh should not be combined with CNS depressants, including sedatives, benzodiazepines, barbiturates, or alcohol, as it may potentiate drowsiness and respiratory depression. The herb's neurotoxic compounds can intensify the effects of these medications unpredictably. Individuals taking anticonvulsants should avoid Ledum marsh entirely, as it may lower seizure threshold. Due to limited interaction data (Evidence Level C), patients on any prescription medications should consult a qualified healthcare provider before use. The potential for serious adverse effects outweighs any theoretical benefits.

What is the safe dosage for Ledum marsh tea?

Traditional preparation uses only 0.5-1 gram of dried herb steeped for 5 minutes in hot water, producing a very dilute tea. This conservative approach reflects the herb's narrow safety margin. Concentrated preparations or higher doses have caused neurotoxicity, dizziness, and hallucinations. Internal use should be limited to brief periods only. Evidence for dosing comes from traditional use rather than clinical studies (Evidence Level C). Given the potential for toxicity, professional guidance is strongly recommended before any internal use of this herb.

Is Ledum marsh safe during pregnancy and breastfeeding?

Ledum marsh is unsafe during pregnancy and breastfeeding and must be avoided entirely. The herb contains ledol and other volatile compounds with documented neurotoxic properties that may cross the placental barrier or pass into breast milk. Traditional contraindications explicitly warn against use in pregnancy. No clinical safety data exists (Evidence Level C), but the risk of fetal harm or infant toxicity is significant. Women who are pregnant, planning pregnancy, or breastfeeding should seek safer alternatives for respiratory or topical concerns from a qualified healthcare provider.

What is the difference between Ledum marsh and Labrador tea?

Ledum marsh (Rhododendron tomentosum, formerly Ledum palustre) and Labrador tea (Rhododendron groenlandicum, formerly Ledum groenlandicum) are related but distinct species with different safety profiles. Ledum marsh contains higher concentrations of toxic ledol and is considered more dangerous for internal use. Labrador tea has a longer history of safe use as a beverage tea among Indigenous peoples of North America. Both plants have been used for respiratory conditions, but they should never be substituted for one another. Evidence distinguishing their safety profiles remains limited (Evidence Level C).

Fiche d'information compilée à partir de PubMed

Cette fiche a été compilée à partir de résumés PubMed (NIH) avec l'assistance d'une IA. Chaque affirmation factuelle est citée par un article PubMed réel (voir la liste des sources). Elle n'a pas encore été révisée par un humain — confirmez auprès d'un professionnel de santé avant utilisation.

Compilé à partir de 30 articles PubMed · modèle : gemma4:31b

Résumé

Rhododendron tomentosum (formerly Ledum palustre), also known as marsh tea or wild rosemary, is a fragrant evergreen shrub used in ethnomedicine for its analgesic, anti-inflammatory, and antimicrobial properties [PMID:23352748].

Contexte

Rhododendron tomentosum Harmaja is an evergreen shrub found in peaty soils across northern Europe, Asia, and North America [PMID:23352748]. It is also referred to as northern Labrador tea, marsh rosemary, or wild rosemary [PMID:23352748].

Usages traditionnels

Since the eighteenth century, it has been used in ethnomedicine to treat rheumatism, cough, cold, and insect bites, and as a repellent [PMID:23352748]. It is used by indigenous peoples in Alaska, Canada, and Greenland to treat a diversity of ailments [PMID:29701283] and is consumed as an aromatic beverage and spice [PMID:25156477].

Composés actifs

The plant contains essential oils rich in sesquiterpene hydrocarbons, specifically palustrol and ledol [PMID:32260539, PMID:24716612]. Non-volatile bioactive components include flavonoids (quercetin, catechin, hyperoside, rutin), phenolic acids (chlorogenic acid), lignan glycosides, and ursolic acid [PMID:40869320, PMID:38474607, PMID:40298804, PMID:29701283].

Mécanisme d'action

Network pharmacology suggests that the plant's anti-inflammatory, antioxidant, and anti-rheumatoid arthritis effects may involve core targets such as NF-κB, HIF-1α, IL-1β, and EGFR [PMID:41507718].

Preuves cliniques

Preuve DPostoperative ecchymosis and edema

Preliminary retrospective review of topical combination of Arnica montana and Rhododendron tomentosum in oculofacial surgery; however, a subsequent review of 11 studies indicated that perioperative Arnica (often combined with Ledum) provided no or limited efficacy [PMID:26863038, PMID:34176651]

Preuve DAcute Myeloid Leukemia (AML)

In vitro and in vivo studies demonstrated that extracts can exert anti-AML activity, potentially attributed to ursolic acid [PMID:29701283]

Preuve DRheumatoid Arthritis (RA)

Essential oils of specific chemotypes showed pro-apoptotic effects on RA synoviocytes in in vitro models [PMID:31672661]

Sécurité et effets indésirables

The beverage should not be consumed more than once daily due to the toxicity of ledol and grayanotoxin [PMID:25156477].

Interactions médicamenteuses

Decoctions of Rhododendron tomentosum leaves may have the potential to inhibit cytochrome P450 3A4 (CYP3A4) mediated metabolism, with inhibition increasing the longer the leaves are brewed [PMID:24971793].

Posologie et administration

A common recipe for the beverage is one teaspoonful of dried leaves brewed in one cup of boiling water for 5 minutes [PMID:25156477]. Consult a healthcare provider.

Synthèse des preuves

The evidence is primarily based on in vitro, in vivo (animal), and retrospective/review data. There is a lack of high-level clinical trial evidence (RCTs) to support therapeutic claims in humans.

Sources PubMed

1.PMID: 23352748 (2013) — Rhododendron tomentosum (Ledum palustre). A review of traditional use based on current research. · Fitoterapia
2.PMID: 40869320 (2025) — Accumulation of Phenolic Compounds in Microshoot Cultures of Rhododendron tomentosum Harmaja (Ledum palustre L.). · International journal of molecular sciences
3.PMID: 26863038 (2017) — Assessing the Effectiveness of Arnica montana and Rhododendron tomentosum (Ledum palustre) in the Reduction of Ecchymosis and Edema After Oculofacial Surgery: Preliminary Results. · Ophthalmic plastic and reconstructive surgery
4.PMID: 25156477 (2015) — Labrador tea--the aromatic beverage and spice: a review of origin, processing and safety. · Journal of the science of food and agriculture
5.PMID: 34885703 (2021) — Essential Oils and Supercritical CO2 Extracts of Arctic Angelica (Angelica archangelica L.), Marsh Labrador Tea (Rhododendron tomentosum) and Common Tansy (Tanacetum vulgare)-Chemical Compositions and Antimicrobial Activities.

Ledum Marsh

Sources et citations

Calculer une dose sûre de Ledum Marsh

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Questions fréquentes

Résumé

Contexte

Usages traditionnels

Composés actifs

Mécanisme d'action

Preuves cliniques

Sécurité et effets indésirables

Interactions médicamenteuses

Posologie et administration

Synthèse des preuves

Sources PubMed

Sources gouvernementales

Ledum Marsh

Sources et citations

Calculer une dose sûre de Ledum Marsh

Plantes associées

Prunus avium

Solanum xanthocarpum

Illicium verum

Questions fréquentes

Résumé

Contexte

Usages traditionnels

Composés actifs

Mécanisme d'action

Preuves cliniques

Sécurité et effets indésirables

Interactions médicamenteuses

Posologie et administration

Synthèse des preuves

Sources PubMed

Sources gouvernementales