USING PLANTS CONTAINING PYRROLIZIDINE ALKALOIDS

Colt's foot in early spring

To use or not to use...that is the question for colt's foot, comfrey, borage, and life root. These and related species contain variable amounts of pyrrolizidine alkaloids (PAs) which are toxic to the human liver in concentrated doses.

Colt's foot in late spring

Colt's foot (Tussilago farfara) is one of the best herbal expectorants and cough suppressants. It's also called "cart-before-horse" because the dandelion-like flowers emerge in early spring and seed out before the hoove-shaped leaves unfold. It's this leaf that's harvested and dried in late spring for medicinal applications. Fortunately, the toxic PAs that it contains are poorly soluble in water so colt's foot can be safely used as an herbal infusion.



Comfrey (Symphytum officinale) is a prolific wound healer in part because it contain's allantoin, a chemical that stimulates cell growth. Comfrey also contains PAs which has resulted in it's sale being banned in some countries including the U.S. It's a good thing the vulnerary effects can be safely obtained by topical application of the leaves in a poultice or salve.

Comfrey in late spring



Life root has purple buds but golden flowers

Equal care must be taken with use of other PA containing herbal medicines. Borage oil (Borago officinalis) is a source of the essential fatty acid gamma-linolenic acid and can be purchased in pyrrolizidine-free capsules. Life root or golden ragwort (Senecio aureus) has safer alternatives for it's astringent and menstrual stimulating effects (see Herbs for Female Problems). The key to safe use of any herbal medicine is your knowledge - about the plant's actions, it's risks, and, if too risky, it's alternatives. 

HERBALIST'S NOTE: Use other topical wound-healing herbs (see Making an Herbal Poultice) instead of comfrey when slow healing is desired or scar prevention is a priority.