Lungwort

Pulmonaria officinalis

Family: Boraginaceae Part used: Aerial parts (leaves, stems) — fresh or dried

Key Compounds

• Mucilage
• Saponins
• Allantoin
• Rosmarinic acid
• Quercetin
• Kaempferol
• Tannins
• Silica
• Potassium
• Pyrrolizidine alkaloids (trace)

Traditional Use

• Respiratory demulcent and expectorant — primary traditional application; the mucilage coats and soothes irritated mucous membranes of the respiratory tract; saponins contribute expectorant activity by thinning and promoting clearance of mucus; the combination of soothing and expectorant effects makes lungwort applicable to both dry, irritated coughs and productive coughs with congestion; traditional European use for bronchitis, chronic cough, and catarrh
• Tissue healing and allantoin content — allantoin stimulates cell proliferation (the same mechanism as comfrey, where allantoin is the primary healing compound); the allantoin content in lungwort is lower than in comfrey but contributes to the respiratory tissue-healing application; the pyrrolizidine alkaloid content is trace-level in *Pulmonaria* (very low compared to comfrey), making the internal use safety profile substantially better than comfrey
• Wound healing (topical) — traditional application of infusion or poultice to minor wounds; allantoin promotes cell proliferation, accelerating wound closure; tannins provide astringent antimicrobial effects; rosmarinic acid contributes anti-inflammatory activity; the topical application parallels the traditional use of comfrey leaf, though at lower allantoin concentrations
• Nutritive spring green — traditionally gathered as a spring vegetable; the fresh young leaves are edible (mild flavour); the high silica and mineral content makes it a nutritive tonic green in the folk tradition of spring cleansing herbs gathered when other greens are scarce

The leaves look like spotted lung tissue. This is why the plant is called lungwort. This is also why it was used to treat lung complaints.

The reasoning was the Doctrine of Signatures — the pre-scientific system that held that plants reveal their therapeutic use through their appearance. Spotted leaves resemble diseased lungs; therefore, spotted-leaf plants treat lung disease. Paracelsus and Jakob Böhme articulated this systematically in the 16th and 17th centuries. The doctrine is not correct as a general principle.

The application to respiratory complaints had some pharmacological support anyway. Mucilage soothes irritated mucous membranes. Saponins thin and help clear mucus. The reasoning was wrong. The application worked.

This tells you something about confirmation bias and something about how traditional medicines accumulate. It does not tell you the Doctrine of Signatures was a reliable method.

Meet the plant

A woodland perennial, 15–30 cm, with hairy white-spotted leaves and flowers that change colour as they age — opening pink, turning blue. Both colours are visible on the same plant simultaneously because flowers open and age at different times. The colour change is caused by a pH shift in the cell vacuoles as the flower ages.

The spots are air-filled intercellular spaces reflecting light differently. They are not disease. They have looked like diseased lung tissue to every European herbalist who has encountered the plant.

What the spots are (and are not)

The white spots on lungwort leaves are caused by raised epidermal cells with air-filled spaces beneath them. The spaces reflect light differently from the surrounding tissue, creating the mottled pattern. The spots are present from the moment the leaf emerges and are more pronounced on mature leaves.

They are not fungal infection. They are not disease. They are a structural feature of the plant that European herbalists in the 16th century decided looked like diseased lung, and used that resemblance as the justification for a respiratory application that had probably already been in use for generations.

The respiratory mechanism

The pharmacological support for the respiratory application:

Mucilage: Coats and soothes irritated mucous membranes. Relevant to dry, irritated, or inflamed respiratory passages.

Saponins: Thin mucous secretions and promote clearance. Expectorant action.

Allantoin: Stimulates cell proliferation. The same compound that makes comfrey effective for wound healing; present in lungwort at lower concentrations. Relevant to respiratory tissue healing in chronic respiratory conditions.

Rosmarinic acid: Anti-inflammatory.

The combination covers both dry, irritated respiratory conditions (mucilage, allantoin) and productive, congested conditions (saponins). This is the traditional characterisation: lungwort for respiratory complaints broadly rather than one specific type.

The pyrrolizidine alkaloid consideration

Lungwort is a Boraginaceae herb. The Boraginaceae family contains many species with pyrrolizidine alkaloids (PAs) — the hepatotoxic compounds that made internal comfrey use illegal in multiple countries. Pulmonaria officinalis contains detectable PA levels in most analyses. The key point: the concentrations are much lower than in comfrey.

The internal use of lungwort at normal therapeutic doses and for short to moderate courses is substantially safer than comfrey. Long-term high-dose internal use warrants caution. Pregnant and breastfeeding individuals should avoid internal use. The topical applications are not a PA concern.

What people actually do with it

Infusion (respiratory): 1–2 teaspoons dried aerial parts per cup, steeped 10–15 minutes. 2–3 cups daily for cough or respiratory congestion. Fresh plant is preferable if available.

Tincture: 2–4 mL in water, 2–3 times daily. Shorter courses are preferable to prolonged use.

Fresh herb poultice (topical): Crushed fresh leaves applied to minor wounds as a topical treatment.

Spring tonic use: Young fresh leaves added to salads or soups in early spring — nutritive use rather than medicinal.

Could you grow this yourself?

Yes, easily — Pulmonaria officinalis is a reliable shade garden perennial. It prefers moist, well-drained soil in shade or partial shade, conditions that suit most woodland garden contexts. The bicolour flowers in early spring (one of the earliest-flowering garden perennials) and the spotted foliage throughout the season make it ornamentally useful as well as medicinal.

Lungwort (プルモナリア) in Japan

Lungwort is primarily ornamental in Japan — the spotted leaves and bicolour flowers are valued in shade garden design, where the plant is grown as ベツレヘムの星 (betsurehemu no hoshi, ‘star of Bethlehem’) or プルモナリア. There is no traditional Japanese medicinal use.

Western herbal supplement availability is limited. The plant’s primary Japanese presence is horticultural.

Things you’re probably wondering

If the Doctrine of Signatures was wrong, why did any of it work? Because the doctrine was mostly applied retrospectively — to justify applications already in use. Humans had been trying plants for ailments for tens of thousands of years before anyone articulated the Doctrine of Signatures. The plants that worked had already been identified. The doctrine provided an explanatory framework for plants that had already proven useful. When it was used prospectively (predicting new applications from plant appearance), it mostly did not work.

Is lungwort safer than comfrey? For internal use: substantially yes. The pyrrolizidine alkaloid content is much lower. The regulatory status is different: comfrey is banned for internal use in the US, Germany, and other countries; lungwort is not under the same restrictions. Treat the same principle (Boraginaceae, PAs, short courses, avoid in pregnancy) with proportionally lower concern.

Botanical details

The full compound list

See Also

• Comfrey — Boraginaceae; higher allantoin and PA content; topical only in current regulatory status
• Marshmallow Root — mucilaginous demulcent; safer for prolonged internal respiratory use
• Mullein — respiratory demulcent; similar cooling, soothing respiratory application

References

• Grieve, M. (1931). A Modern Herbal. Dover. (Doctrine of Signatures context and historical uses)
• Hoffmann, D. (2003). Medical Herbalism: The Science and Practice of Herbal Medicine. Healing Arts Press.
• Wichtl, M. (Ed.). (2004). Herbal Drugs and Phytopharmaceuticals. Medpharm Scientific.
• Roeder, E. (2000). Medicinal plants in Germany with pyrrolizidine alkaloids. Die Pharmazie, 55(9), 711–726. (PA content review)