Historical Note

Horseradish is a commonly used spice with a long history of use in traditional medicine. The leaves are used in cooking and as a salad green. Horseradish is one of the ‘five bitter herbs’ of the biblical Passover.

Common Name


Other Names

Amoraciae rusticanae radix, great mountain root, great raifort, mountain radish, pepperrot, red cole

Botanical Name / Family

Armoracia rusticana, synonym Armoracia lopathifolia; Cochlearia armoracia, Nasturtium armoracia, Roripa armoracia (family Brassicaceae [Cruciferae])

Plant Parts Used

Fresh or dried roots and leaves

Chemical Components

Horseradish root contains volatile oils: glucosinolates (mustard oil glycosides); gluconasturtiin and sinigrin (S-glucosides); coumarins (aesculetin, scopoletin); phenolic acids, including caffeicacid derivatives and hydroxycinnamicacid derivatives, ascorbic acid; asparagin; resin; and peroxidase enzymes. Horseradish is one of the richest plant sources of peroxidase enzymes, which are commonly used as oxidising agents in commercial chemical tests.

Main Actions

Horseradish is widely known for its pungent burning flavour. The pungency of horseradish is due to the release of allyl isothiocyanate and butylthiocyanate upon crushing. These mustard oil constituents may irritate the mucous membranes upon contact or inhalation and may act as circulatory and digestive stimulants; however, the mechanism of action has not been fully elucidated. It has been found that topical application of allyl isothiocyanate to the skin activates sensory nerve endings producing pain, inflammation and hypersensitivity to thermal and mechanical stimuli due to depolarising the same sensory neurons that are activated by capsaicin and tetrahydrocannabinol (THC).


The mustard oils released when horseradish is crushed may be responsible for this activity.


Again, it is suspected that the mustard oils may be responsible.

Other Actions

Isothiocyanates may inhibit thyroxine formation and be goitrogenic although this has not been demonstrated clinically.

The peroxidase enzymes assist in wound healing, whereas the sulphur-containing compounds may decrease the thickness of mucus by altering the structure of its mucopolysaccharide constituents. Antispasmodic and antimicrobial effects have also been.

Horseradish has been found to lower plasma cholesterol and faecal bile acid excretion in mice fed a cholesterol enriched diet possibly due to interference with exogenous cholesterol absorption.

Horseradish has also been found to contain compounds that inhibit tumour cell growth and COX-1 enzymes.

Clinical Use

The therapeutic effectiveness of horseradish has not been significantly investigated.


Horseradish is widely used in combination with other ingredients such as garlic in herbal decongestant formulations. Although clinical research is not available to confirm efficacy, anecdotal evidence suggests that a mild, transient decongestant effect occurs.

Other Uses

It has been used traditionally to treat both bronchial and urinary infections, joint and tissue inflammation, as well as treating gall bladder disorders, reducing oedema and as an abortifacient.

Dosage Range

• The typical dose of horseradish is 2-20 g/day of the root or equivalent preparations.

• Topical preparations with a maximum of 2% mustard oil content are commonly used.

Adverse Reactions

Despite the potential for severe irritation, horseradish is generally recognised as safe for human consumption in quantities used as food. Consuming large amounts of horseradish can cause gastrointestinal upset, vomiting and diarrhea, and irritation of mucous membranes. Skin contact with fresh horseradish can cause irritation and blistering or allergic reactions.

Significant Interactions

None known.

Contraindications and Precautions

Internal use should be avoided in people with stomach and intestinal ulcers and kidney disorders, as well as in children under the age of 4 years.

Traditionally, horseradish is considered a warming herb that will exacerbate any ‘hot’ condition and is specifically indicated for ‘cold’ conditions.

Pregnancy Use

The mustard oils released upon crushing are potentially toxic, therefore doses exceeding dietary intakes are contraindicated.

Practice Points / Patient Counselling

• Horseradish has been used as a vegetable, condiment, diuretic and treatment for bronchial and urinary infections, joint and tissue inflammation, and swelling.

• It is widely used together with other herbal ingredients such as garlic, as a decongestant in the treatment of colds and sinusitis.

• No scientific investigation has been undertaken to support its use, although anecdotal evidence suggests it may be useful.

• Horseradish is generally safe when the root is ingested in usual dietary amounts, although excessive intake may cause irritation to the stomach, respiratory tract and kidneys.

Answers to Patients’ Frequently Asked Questions

What will this herb do for me?

Anecdotal evidence suggests it may have decongestant effects and is a very popular treatment when combined with other herbs such as garlic, to relieve the symptoms of colds and sinusitis.

When will it start to work?

It may relieve symptoms within the first few doses, but scientific tests are not available to confirm this.

Are there any safety issues?

Horseradish can be quite irritating for some people due to its bitter and pungent characteristics.