Wise Mind Herbs

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Rosebay willowherb - Epilobium angustifolia

Rosebay willowherb (Epilobium angustifolium L., family Onagraceae), also known as fireweed, great willowherb, or blooming sally, is a perennial flowering plant native to temperate regions of the Northern Hemisphere. Not to be confused with other Epilobium species like small-flowered willowherb (Epilobium parviflorum) or other plants in the Onagraceae family, Rosebay willowherb has gained attention in traditional medicine and modern research for its potential health benefits.

Image source and license: https://commons.wikimedia.org/wiki/File:Epilobium_angustifolium_02.jpg.
Modified by Peter Jorgensen.

Botanical Identification and Common Names

Botanical name: Epilobium angustifolium L. (syn. Chamaenerion angustifolium)

Common names include:

• Rosebay willowherb
• Fireweed
• Great willowherb
• Blooming sally
• Bombweed (UK)
• Wickup

Plants sometimes confused with Epilobium angustifolium but are distinct species:

• Small-flowered willowherb (Epilobium parviflorum)
• Broad-leaved willowherb (Epilobium montanum)
• American willowherb (Epilobium ciliatum)

Bioactive Compounds

The therapeutic properties of rosebay willowherb are attributed to several bioactive compounds including:

• Flavonoids (quercetin, kaempferol, myricetin derivatives)
• Phenolic acids (gallic acid, ellagic acid)
• Ellagitannins (oenothein A and B)
• Sterols (β-sitosterol, campesterol)
• Essential oils
• Anthocyanins

Evidence-Based Health Benefits

Research suggests the following potential health benefits of rosebay willowherb:

• Benign Prostatic Hyperplasia (BPH): The strongest evidence supports the use of Epilobium extracts for BPH symptoms. Several clinical studies have demonstrated that oenothein B exhibits anti-inflammatory and anti-proliferative effects on prostate cells.
• Anti-inflammatory properties: Extracts have demonstrated inhibition of inflammatory mediators and processes in both in vitro and in vivo studies.
• Antioxidant activity: The plant's phenolic compounds exhibit significant free-radical scavenging effects.
• Antimicrobial effects: Various extracts have shown inhibitory activity against certain bacteria and fungi in laboratory studies.
• Mild analgesic effects: Traditional uses for pain management have some preliminary scientific support.
• Mild anxiolytic properties: Emerging evidence suggests potential benefits for anxiety, though human studies are limited.

It is important to note that while traditional use claims wider applications for digestive disorders, skin conditions, and respiratory ailments, the clinical evidence for these uses remains preliminary.

Dosage Recommendations

Standardized dosages from clinical studies vary based on preparation method and extract concentration:

• Dried herb: 2-4g of dried aerial parts as an infusion (tea), taken 2-3 times daily
• Liquid extract (1:1): 2-4 mL, three times daily
• Tincture (1:5 in 45% alcohol): 2-4 mL, three times daily
• Standardized extract (containing 10-15% polyphenols or 1-3% oenothein B): 300-500 mg, twice daily

For BPH specifically, clinical studies have used standardized extracts containing 1-3% oenothein B at dosages of 300-500 mg daily for periods of 2-6 months.

Safety Profile and Side Effects

Rosebay willowherb is generally recognized as safe when consumed in typical dietary or recommended therapeutic amounts. However, the following adverse effects have been reported:

• Mild gastrointestinal disturbances (nausea, diarrhea)
• Potential hypersensitivity reactions in sensitive individuals
• Headache (rare)
• Dizziness (rare)

No serious adverse events have been consistently documented in the scientific literature. The safety of long-term use (>6 months) has not been well-established in clinical studies.

Contraindications and Precautions

• Pregnancy and lactation: Insufficient safety data; use is not recommended
• Hormone-sensitive conditions: Theoretical concerns about possible phytoestrogenic effects
• Drug interactions: May potentially interact with medications metabolized by cytochrome P450 enzymes, though clinical significance is unclear
• Children: Insufficient safety data for therapeutic use in pediatric populations

High-Dose Studies and Knowledge Gaps

Few studies have systematically evaluated doses above the therapeutic ranges mentioned. The limited research available indicates:

• No additional therapeutic benefits have been consistently demonstrated at doses exceeding 500 mg of standardized extract daily
• Higher doses (>1000 mg daily) may increase the risk of gastrointestinal side effects
• No systematic toxicity studies have evaluated very high doses in humans

Significant knowledge gaps exist regarding:

• Long-term safety profiles (>1 year of continuous use)
• Potential interactions with pharmaceutical medications
• Detailed dose-response relationships for various indications
• Comparative effectiveness against standard pharmaceutical treatments
• Optimal standardization parameters for different therapeutic applications

While rosebay willowherb is commonly available in dietary supplements, teas, and traditional preparations, few standardized pharmaceutical products exist.

Research Outlook

Recent research trends point toward increasing interest in the specific mechanisms of action of oenothein B and other bioactive compounds in rosebay willowherb. The potential applications for inflammatory conditions and urological health continue to be the most promising areas of investigation. Larger, well-designed clinical trials are needed to better establish efficacy for specific indications.

References

Barbarossa, A., Rosato, A., Carocci, A., Arpini, S., Bosisio, S., Pagni, L., ... & Caprioli, G. (2025). Efficacy of Willow Herb (Epilobium angustifolium L. and E. parviflorum Schreb.) Crude and Purified Extracts and Oenothein B Against Prostatic Pathogens. Antibiotics, 14(2), 117.

Deng, L., Zong, W., Tao, X., Liu, S., Feng, Z., Lin, Y., ... & Chen, M. (2019). Evaluation of the therapeutic effect against benign prostatic hyperplasia and the active constituents from Epilobium angustifolium L. Journal of ethnopharmacology, 232, 1-10.

Gevrenova, R., Zengin, G., Ozturk, G., & Zheleva-Dimitrova, D. (2025). Exploring the Phytochemical Profile and Biological Insights of Epilobium angustifolium L. Herb. Plants, 14(3), 415.

Kosalec, I., Kopjar, N., & Kremer, D. (2013). Antimicrobial activity of willowherb (Epilobium angustifolium L.) leaves and flowers. Current drug targets, 14(9), 986-991.

Nowak, A., Zagórska-Dziok, M., Ossowicz-Rupniewska, P., Makuch, E., Duchnik, W., Kucharski, Ł., ... & Klimowicz, A. (2021). Epilobium angustifolium L. extracts as valuable ingredients in cosmetic and dermatological products. Molecules, 26(11), 3456.

Piwowarski, J. P., Bobrowska-Korczak, B., Stanisławska, I., Bielecki, W., Wrzesien, R., Granica, S., ... & Kiss, A. K. (2017). Evaluation of the effect of Epilobium angustifolium aqueous extract on LNCaP cell proliferation in in vitro and in vivo models. Planta Medica, 83(14/15), 1159-1168.

Schepetkin, I. A., Ramstead, A. G., Kirpotina, L. N., Voyich, J. M., Jutila, M. A., & Quinn, M. T. (2016). Therapeutic potential of polyphenols from Epilobium angustifolium (Fireweed). Phytotherapy research, 30(8), 1287-1297.