Herb library · Herb · Rumex crispus
Yellow dock
A common weed with wavy-edged leaves and a long yellow root, used in 19th-century American medicine as a tonic and for skin conditions. No trials in people exist; the plant contains oxalic acid, and a 1990 case report describes a man who died after eating it.
Serious warning
A 1990 case report describes a 53-year-old man who died 72 hours after eating curled dock: he developed severe low calcium, acid buildup and liver failure, and crystals were found in his liver and kidneys. The authors warn of the risk of using these plants as food or medicine.
Traditional use
The dock most used by 19th-century American physicians, who gave the root for skin diseases and as a tonic. Its young leaves, like those of some other docks, have been eaten as greens, and the sour taste of the leaf stalks comes from the oxalic acid they contain.
Traditional energetics
Galenic (hot or cold, dry or moist)
Cold and dry. Culpeper's Complete Herbal (1814), p. 244 (opens in a new tab)
What studies show
- Insufficient
Skin conditions and digestion: no clinical trials in people were found for any use. The only study in people found in PubMed is a report of fatal poisoning.
Be careful of
Cautions
- ConditionDock contains oxalic acid, especially in the leaf stalks (King's Dispensatory), and the man in the fatal case had crystal deposits in his liver and kidneys.
- AmountThe case report does not say how much was eaten, and there is no established safe amount.
- Ask a clinicianTalk with a clinician or pharmacist before using this if you take prescription medicines, are pregnant or breastfeeding, or are giving it to a child.
From the old books
What herbals and dispensaries of the past printed. History, in their words.
“These various dock-roots have hardly any odor, an astringent, bitterish taste, and yield their virtues to alcohol, or boiling water. The young leaves of some of the species are sometimes used as greens.”
Sources
- Fatal poisoning by Rumex crispus (curled dock): pathological findings and application of scanning electron microscopy (1990) (opens in a new tab) · NIH · read September 25, 2026
Reviewed September 25, 2026.