# Horseradish (Armoracia rusticana) *Mountain radish, great raifort, red cole; French *moutarde des Allemands*; Gerard’s *Raphanus rusticanus*; *Cochlearia armoracia* L., now *Armoracia rusticana** **Known today as.** *Armoracia rusticana*, of the family Cruciferae, long cultivated and of obscure origin; Grieve reports that some authorities think it native to eastern Europe, from the Caspian through Russia and Poland to Finland. The fresh root is the drug. Unbroken it has no smell; scraped or bruised it gives off its pungent oil, because the glucoside sinigrin and the enzyme myrosin that splits it lie in separate cells and meet only when the cells are crushed, producing allyl isothiocyanate, the same oil as black mustard’s. Boiling makes it vapid and inert. Kind: Plant > **Caution.** Grieve notes that taken too freely it is emetic, and that its oil is so pungent that a drop scents a room; as a poultice it acts like a mustard plaster. None of the sources read for this entry reports on its safety as a medicine taken alone. ## What was it used for? A stimulant and diuretic, and a sauce. Grieve calls it stimulant, aperient, rubefacient, diuretic, and antiseptic: with oily fish or rich meat “a spur to complete digestion,” a strong diuretic used in stone and dropsy, laid on as a poultice instead of a mustard plaster for rheumatism and chilblains, and made into a syrup for hoarseness and a remedy for worms in children. ## What does modern science say? No European monograph for the root alone was found for this entry. In modern trials it appears in combination: a German phase III trial published in 2026 gave women with recurrent cystitis a combination of nasturtium herb and horseradish root or placebo for six months, and found the risk of recurrence reduced by about a third, with no more adverse effects than placebo. That result belongs to the combination, not to horseradish alone. ## Pharmacognosy and toxicology - **sinigrin**: a glucoside, split by the enzyme myrosin when the cells are crushed - **myrosin**: the enzyme, held in separate cells - **allyl isothiocyanate**: the pungent volatile oil, the same as black mustard’s **Mechanism.** The volatile oil does not exist in the unbroken root; it forms only when scraping or bruising brings sinigrin and myrosin together. **Standing.** There is no European monograph for the root alone. A 2026 phase III trial tested it only in combination with nasturtium herb. ## What lore surrounds it? Gerard used it to illustrate the old doctrine of antipathies: “Divers thinke that this Horse Radish is an enimie to Vines,” so that a vine planted near it “bendeth backward from it as not willing to have fellowship with it.” Folkard records that it is said to be one of the five “bitter herbs” of the Mishna eaten at Passover, with coriander, horehound, lettuce, and nettle, and that it is under Mars. Grieve explains that ‘horse’ in its name means coarse, to distinguish it from the edible radish, as in horse-mint and horse chestnut. ## What did the older authorities say? **Gerard (1597) and Parkinson (1640), as Grieve quotes them.** In Gerard’s day the English still knew it as a drug: he reported that “the Horse Radish stamped with a little vinegar put thereto, is commonly used among the Germans for sauce to eate fish with,” as the English used mustard. By 1640 Parkinson found it eaten in England too, “but, as I said, it is too strong for tender and gentle stomaches.” Its old French name, the Germans’ mustard, records the same borrowing. ## Sources - Grieve, M. *A Modern Herbal*, “Horseradish.” As published on botanical.com. - Folkard, R. (1884). *Plant Lore, Legends, and Lyrics*, “HORSERADISH.” Project Gutenberg, 44638. - Albrecht U, et al. (2026). Clinical evaluation of the efficacy and safety of nasturtium herb and horseradish root versus placebo in the continuous prophylaxis of recurrent uncomplicated cystitis: a double-blind randomised clinical trial. *BMC complementary medicine and therapies*. PMID 41782129. - Grieve, M. *A Modern Herbal*, “Horseradish.” As published on botanical.com. - Albrecht U, et al. (2026). Clinical evaluation of the efficacy and safety of nasturtium herb and horseradish root versus placebo in the continuous prophylaxis of recurrent uncomplicated cystitis: a double-blind randomised clinical trial. *BMC complementary medicine and therapies*. PMID 41782129. --- *Horseradish.* In *Materia Medica*, edited by B. C. P. Statema. Version 1, revised 2026-10-17. The Thinking Press. https://thethinkingpress.org/materia-medica/horseradish Historical description, not medical advice.