External remedies — skin, wounds, inflammation

The safest medicinal uses are external. Skin absorbs compounds poorly compared to the gut, which means overdose is nearly impossible and side effects are rare. Start here if you are cautious.

Comfrey (Symphytum officinale) is the classic wound herb. Allantoin in the leaves and roots stimulates cell proliferation — broken bones, sprains and bruises heal faster under comfrey poultices. This is documented in clinical trials. But never take comfrey internally; it contains pyrrolizidine alkaloids that cause liver failure. Grow it as a perennial in rich, moist soil. Harvest leaves in spring and summer; chop and apply fresh as a poultice, or dry and infuse in oil (1:5, 4 weeks). Use only on unbroken skin — it can seal over wounds before deep tissue heals, trapping infection.

Lavender (Lavandula angustifolia) is anti-inflammatory and mildly anaesthetic. Lavender oil reduces pain and anxiety when applied to the skin or inhaled — the linalool and linalyl acetate are the active compounds. Grow lavender in full sun, gritty alkaline soil, minimal water. English lavender (Angustifolia varieties like Hidcote, Munstead) has the highest oil content; French lavender (Stoechas) is ornamental but weaker. Harvest flowers just as they open; dry in bunches upside-down in a warm, dark place. Infuse in oil or make a water-based spray (5 drops essential oil per 100ml water) for minor burns, insect bites, tension headaches.

Plantain (Plantago lanceolata, ribwort plantain, or P. major, greater plantain) is the weed you have been pulling up that stops bleeding and draws out splinters. The leaves contain mucilage and tannins; they are astringent and vulnerary. Crush a fresh leaf and apply to minor cuts, stings, bites — it works instantly. Plantain grows in lawns, paths, waste ground. Harvest young leaves spring to autumn; use fresh. Dried leaves can be infused as a wash for skin irritation.

Arnica (Arnica montana) treats bruises and sprains — but only as a cream or oil, never internally (it is toxic). Arnica stimulates white blood cell activity and disperses trapped blood. It is a high-altitude European perennial, difficult to grow in lowland Britain. Buy the dried flowers if you cannot grow it; infuse in oil (1:10, 6 weeks) and strain. Apply to bruises, not broken skin.