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Lythrum salicaria
Gewöhnlicher Blutweiderich · (Lythrum salicaria)
Loosestrife family (Lythraceae)
Description
Tall spikes of vivid magenta flowers mark out purple loosestrife along riverbanks, ditches and wet meadows in high summer — its very name reflects a traditional reputation as a blood-stopping herb. The flowering herb of this loosestrife-family plant is rich in tannins, up to 14 percent in the flowers, which act astringently on mucous membranes. Dioscorides already described a root decoction for dysentery and bleeding, and to this day tea from the flowering herb is used in folk medicine for diarrhoea, the tannins helping to constrict the intestinal lining. Externally, strong infusions are applied as compresses for wounds, eczema and skin infections, and used as a gargle for sore throat; the tea was also traditionally drunk for excessively heavy menstrual bleeding. In contemporary herbal medicine a tincture serves as a concentrated tannin preparation for irritable bowel complaints. At typical tea doses of two to four grams daily, purple loosestrife is well tolerated; sensitive stomachs should start with a small amount given the high tannin content.
Tea from the flowering herb (decoction or infusion) is used in folk medicine for diarrhoea and dysentery. The high tannin content (up to 14 % in flowers) acts astringently on the intestinal mucosa, reducing secretion.
Preparation & dosage
Pour 250 ml of hot water over 2–4 g of dried herb, steep for 10 minutes, strain; 2–3 times daily.
- Dry amount
- 2–4 g
- Doses per day
- 3×
Decoction of the root (1–3 g per 250 ml water) was traditionally used for dysentery and haemorrhage, as reported already by Dioscorides. The root contains approx. 9 % tannins.
Preparation & dosage
Simmer 1–3 g root in 250 ml water for 15 minutes, strain.
- Dry amount
- 1–3 g
- Doses per day
- 3×
Compresses soaked in a strong tea from the flowering herb were applied externally to wounds, ulcers, eczema, and skin infections (impetigo). The astringent and antimicrobial action supports wound healing.
Gargling with purple loosestrife tea was used for sore throats and pharyngitis. Tannins constrict mucous membranes and reduce inflammatory irritation.
Purple loosestrife tea was traditionally used for excessive menstrual bleeding. The styptic (haemostatic) properties are attributed to the high tannin and flavonoid content.
Sitz baths or local baths with purple loosestrife extract were used in folk medicine for vaginal problems (leucorrhoea) and perianal complaints. PFAF also notes application for eczema.
Tincture of the flowering herb is used in contemporary herbal medicine as a concentrated tannin preparation — internally for irritable bowel complaints, externally as an antiseptic compress.
Well tolerated with normal tea use (2–4 g daily). High tannin content may cause nausea in sensitive stomachs — start with a small dose or drink after meals.
No reliable data on use during pregnancy. Avoid as a precaution.
PFAF notes the herb can be safely given to nursing infants for diarrhoea; however, modern clinical data are absent — caution advised.
Traditionally described as safe for all ages. Due to lack of modern safety data, use a low dose for children under 12 and consult a health professional.
Drug interactions
Eisenpräparate / Schwermetallsalze
Tannins can complex mineral ions and inhibit their absorption — a gap of at least 2 hours is recommended.
Contraindications
- Known hypersensitivity to plants of the family Lythraceae.
Harvested part: flowering herb
- Time of day:
- Harvest in the morning after the dew has dried.
- Drying:
- Dry loosely bundled or spread out at 35–40 °C until the stems snap. Protect from light to minimise anthocyanin loss.
- Storage:
- 12 months — Store in a dark, dry, airtight container (paper bags or glass jars).
- Time of day:
- Autumn, after the plant has finished flowering.
- Drying:
- Clean roots, slice, and dry at 40–50 °C.
- Storage:
- 24 months — Store in sealed glass jars in a dark, dry place.
- Lythrariin / SalicarinGlycosideContent: < 1 %Aerial parts
Characteristic phenolic glycoside of purple loosestrife; contributes to astringent and antimicrobial activity.
- Hydrolisierbare Gerbstoffe (Ellagsäure, Gallussäure-Derivate)TanninContent: 8,5–13,7 %Flower
Flowers contain up to 13.7 %, stems approx. 10.5 %, roots approx. 8.5 % tannins — primary active compounds.
- VitexinFlavonoidAerial parts
C-glycosyl flavone with antioxidant and anti-inflammatory properties.
- OrientinFlavonoidAerial parts
Additional C-glycosyl flavone; antioxidant activity documented.
- AnthocyaneFlavonoidFlower
Responsible for the red-purple flower colour; antioxidant activity.
- p-CumarsäurePhenolic acidAerial parts
Hydroxycinnamic acid derivative with antioxidant properties.
- EllagsäurePhenolic acidAerial parts
Polyphenol with antimicrobial and anti-inflammatory activity; hydrolysis product of ellagitannins.
- PektinePolysaccharideAerial parts
Mucilaginous polysaccharides that protect the gastric mucosa and complement the astringent action.
- [2]MonographLythrum salicaria — Plants For A Future (PFAF)(accessed: 2026-05-22)
- [4]MonographPiwowarski JP, Granica S, Kiss AK. Lythrum salicaria L.—Underestimated medicinal plant from European traditional medicine. A review. J Ethnopharmacol. 2015;170:226-250.(accessed: 2026-05-22)
- [3]BookKing's American Dispensatory (1898) — Lythrum salicaria (Henriette's Herbal)(accessed: 2026-05-22)
- [1]WikipediaGewöhnlicher Blutweiderich (Wikipedia DE)(accessed: 2026-05-22)