© Walther Otto Müller, Köhler's Medizinal-Pflanzen (1887), plate 088 · Public domain · Commons
Flax
Lein · (Linum usitatissimum)
Flax family (Linaceae)
Description
Flax, also called linseed, ranks among the oldest cultivated plants of all and was grown for millennia for fibre and seed alike. Its slender upright stem bears narrow, lance-shaped leaves and delicate five-petalled flowers, usually sky blue, each lasting only a single day. From them come round capsules holding the glossy, flat-oval seeds in brown or golden yellow. Medicinally it is the ripe, dried seed that is used. It is rich in mucilage, in fixed oil with a high share of alpha-linolenic acid, and in dietary fibre. Taken whole or freshly cracked with plenty of liquid, it swells in the gut and gets a sluggish digestion moving — drinking enough alongside is the decisive part. As a warm poultice, linseed was formerly laid on inflamed patches of skin and on boils.
Herbal bulk laxative for habitual constipation — clinically well documented.
Preparation & dosage
BULK LAXATIVE (constipation): 10–15 g of whole or bruised seeds per single dose, two to three times daily, each taken with at least 150 ml water, milk or juice, maintaining ample fluid intake through the day. Onset after 12–24 hours, full effect sometimes only after 2–3 days. IMPORTANT: never take without sufficient fluid (risk of choking and intestinal obstruction) and not immediately before bedtime. Keep at least ½ to 1 hour between this and other medicines (the mucilage can delay their absorption). If constipation does not resolve within 3 days, consult a doctor or pharmacist.
- Dry amount
- 10–15 g
- Doses per day
- 3×
⚠ Age restriction: ≥ 12 years — Not for children under 12 due to lack of data.
Sources: [1]
Soothing linseed gel for mild gastrointestinal discomfort (traditional).
Preparation & dosage
DEMULCENT PREPARATION (mild gastrointestinal discomfort): Soak 5–10 g of whole or broken seeds in 250 ml water, take up to three times daily about half an hour before eating; swelling must be complete at the time of consumption. A soothing (demulcent) home remedy. If symptoms persist for more than 1 week, seek medical advice.
- Dry amount
- 5–10 g
- Doses per day
- 3×
⚠ Age restriction: ≥ 12 years — Not for children under 12 due to lack of data.
Sources: [1]
IMPORTANT: Always take linseed with plenty of fluid — without enough water the seeds can swell and block the throat or oesophagus (choking risk) or cause intestinal obstruction. If you experience chest pain, vomiting, or difficulty swallowing or breathing after taking it, seek immediate medical attention. Do NOT use with constrictions of the gastrointestinal tract, diseases of the oesophagus or stomach, existing intestinal blockage (ileus), intestinal paralysis or megacolon. Keep at least ½ to 1 hour between linseed and other medicines. Not recommended during pregnancy and lactation or for children under 12 due to insufficient data; possible oestrogen-like effect — avoid long-term use with hormone-dependent tumours. Use crushed seed promptly (the oil turns rancid quickly).
Possible oestrogen-like effect; safety not established — not recommended during pregnancy.
Insufficient data — not recommended during lactation.
Not for children under 12 due to lack of data.
Drug interactions
Andere Arzneimittel (allgemein)
As a bulk-forming agent, linseed can delay the absorption of concurrently taken medicines — keep at least ½ to 1 hour apart.
Peristaltikhemmende Mittel (z. B. Opioide, Loperamid)
Concurrent use raises the risk of intestinal obstruction — only under medical supervision.
Contraindications
- Existing intestinal blockage (ileus), intestinal paralysis, megacolon or constrictions of the gastrointestinal tract.
- Diseases of the oesophagus or stomach, difficulty swallowing.
- Hypersensitivity to linseed.
Harvested part: ripe seed
- Time of day:
- In dry weather, when the capsules are ripe and brown.
- Drying:
- Harvest ripe capsules, post-dry, thresh out the seeds and dry them fully in an airy, shaded place.
- Storage:
- 12 months — Store whole seeds dry, cool and away from light in airtight containers; use crushed seed promptly (oil oxidises).
- Schleimstoffe (Polysaccharide)MucilageContent: 3–6 %Seed
Swell with water into a gel; underlie the laxative and soothing effect (per EMA monograph).
- Fettes Öl mit Alpha-Linolensäure (ALA)Essential oilContent: 30–45 %Seed
A fixed (not volatile) oil, very rich in the omega-3 fatty acid ALA.
- Lignane (Secoisolariciresinol-Diglucosid, SDG)Phenolic acidSeed
Converted by gut bacteria to enterodiol/enterolactone; phyto-oestrogenic properties.
- Cyanogene Glykoside (Linustatin, Linamarin)GlycosideSeed
Can release hydrocyanic acid; hence moderation and heating are advised. Safe at customary amounts.
- BallaststoffePolysaccharideContent: 4–7 %Seed
Dietary fibre; together with the mucilage the seeds contain nearly 25 % bulk material.
- ProteinOtherContent: 20–25 %Seed
High protein content of the seed.
- [1]MonographEuropean Union herbal monograph on Linum usitatissimum L., semen (EMA/HMPC/377675/2014)(accessed: 2026-06-10)
- [3]MonographCliniTox Giftpflanzen — Linum usitatissimum L.: sehr stark giftig +++ (Institut für Veterinärpharmakologie und -toxikologie, Universität Zürich)(accessed: 2026-08-10)
- [2]WikipediaSaat-Lein — Wikipedia (DE)(accessed: 2026-06-10)
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