Know what you're putting in your body.

158 herbs, nutrients, and compounds. What the science says, what tradition knew, and what to watch for. Founding members keep this running.

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GENERAL IMMUNITY

Coltsfoot

Tussilago farfara

also known as coltsfoot leaf

Weak — and a real safety concern

Coltsfoot — Köhler 1887 botanical illustration

A bright yellow early-spring wildflower whose leaves and flowers were used in European folk medicine for cough and respiratory complaints — the Latin name 'tussilago' means 'cough remedy.' But coltsfoot contains pyrrolizidine alkaloids that cause irreversible liver damage, and the herb has been restricted or withdrawn in most regulated markets. The traditional use is real; the risk is also real.

Long traditional European use for cough, bronchitis, and respiratory irritation
Mucilage content provides mild soothing of irritated airway tissue
PA-free preparations (where the toxic alkaloids have been removed) retain the soothing effects without the liver risk — but quality control varies
Other safer respiratory herbs — mullein, marshmallow, slippery elm, plantain — have similar soothing effects without coltsfoot's safety concerns

Contains pyrrolizidine alkaloids (PAs) that cause veno-occlusive liver disease — a condition that can be irreversible and fatal

Restricted or withdrawn from sale in Germany, Austria, the United Kingdom, and other regulated markets

Skip with any pre-existing liver condition

Skip during pregnancy — PAs cross the placenta and can cause fetal liver injury

Skip during nursing — PAs transfer through breast milk and have caused infant liver injury

Skip in infants and small children

Use caution with medications metabolized by the liver

Genuinely PA-free preparations are difficult to verify; safer respiratory herbs are widely available

Reference works that recommend coltsfoot without flagging the PA issue are out of date

Memorial Sloan Kettering About Herbs · EMA Herbal Medicinal Product Monographs · American Botanical Council HerbMedPro · Memorial Sloan Kettering About Herbs · EMA Herbal Medicinal Product Monographs · American Botanical Council HerbMedPro

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