What is Horseradish?

Horseradish is the hot white root of a cabbage-family plant. Most people meet it grated into a sauce for beef, ham or fish. Old herbals call it Cochlearia armoracia; botanists now call it Armoracia rusticana.

That old name ties it to scurvy-grass, Cochlearia officinalis. The two plants were once grouped together. Sailors ate both, because the fresh root holds some vitamin C.

American folk and Eclectic healers used it for blocked sinuses, coughs, swelling and sore joints. Human evidence for those uses is thin. Traditional use is not proof that a remedy works, and it is not proof that it is safe.

The root is also a strong irritant. It can burn the mouth, the stomach and the skin. That hazard shapes most of the advice on this page.

How does Horseradish work?

Grating or chewing the root starts a chemical reaction, and that reaction makes the heat you feel.

Intact root holds a compound called sinigrin. Damage to the cells lets an enzyme, myrosinase, act on it. The result is allyl isothiocyanate, the sharp "mustard oil" vapour.

That vapour irritates the lining of the nose, eyes and throat. The sting, the watering eyes and the sudden runny nose are a direct irritant effect. They are real, but they are brief.

Folk writers took this clearing feeling as proof the root fought infection. That step has not been shown in people.

In test tubes, horseradish mustard oils slow the growth of several bacteria and fungi. Lab dishes are not bladders or sinuses. Whether anything like this happens inside the body is not established.

In cell and animal work, related isothiocyanates change liver enzymes and dampen some markers of inflammation. These are early findings. They do not show a benefit for any illness in people.

What forms does Horseradish come in?

You can buy horseradish as a food, as a herbal product, or as a concentrated oil. Only the first two are for home use.

Food forms:

- Fresh root, whole or grated. - Prepared horseradish, grated root held in vinegar. - Creamed sauces and most "wasabi" pastes, which are usually horseradish with dye.

Herbal forms:

- Dried root powder in capsules or tablets. - Combination tablets with nasturtium herb, sold in Germany and some other countries. - Tinctures and syrups.

Traditional external form:

- A poultice of grated root, applied to the skin. This is the form most likely to cause blisters and burns.

Horseradish essential oil also exists. It is sold for lab and industrial use. Never swallow it and never put it on skin.

Where it comes from:

Horseradish has a long record in European and North American folk medicine.

Early writers grouped it with scurvy-grass. Both were carried on ships and eaten fresh. Both were credited with keeping scurvy away.

Nineteenth-century American Eclectic physicians listed the root as a stimulant and a diuretic (a water-losing agent). King's American Dispensatory described its use for dropsy, which is the old word for fluid swelling. It also appears there for hoarseness and poor appetite.

American home practice used it in other ways:

- Grated root sniffed or eaten for a blocked nose. - Root in vinegar or syrup for coughs.

- Poultices laid on aching joints as a counter-irritant, meaning something that reddens the skin to distract from pain. - Root steeped in cider as a spring tonic.

Germany's Commission E later reviewed the root and allowed it for colds and for supporting treatment of urinary infections. That body set limits too, including a ban on use in young children.

None of this history shows that the root treats any disease. It records what people did and why they thought it helped.

What does Horseradish help with?

• Blocked nose and sinus congestion: This is the best-known folk use, and the only one you can feel working. The vapour makes your nose run and your eyes water within seconds. That is an irritant reflex, not a treatment for infection. The effect fades in minutes. No good trials show that horseradish shortens a cold or clears a sinus infection. It may make you more comfortable for a short while. It may also sting enough that you dislike it.
• Coughs and chesty colds: Tradition used root syrups and vinegars to loosen a cough. Evidence in people is lacking. No controlled trial supports horseradish alone for cough. Any effect is likely the same brief irritant tingle. A cough lasting more than three weeks needs a doctor, not a kitchen remedy.
• Urinary tract infection, as an add-on only: This is the use with the most human data, and the data is still weak. Most of it comes from a German product that mixes horseradish root with nasturtium herb. Studies suggest it may reduce repeat infections in some people. Many of these studies were open-label or funded by the maker. Horseradish on its own has not been tested this way. A urinary infection can reach the kidneys. Do not treat one yourself, and do not delay antibiotics if a doctor advises them.
• Joint and muscle aches, used on the skin: Folk practice laid grated root on painful joints to draw heat and redness to the area. There are no modern trials of horseradish poultices. The redness is real, and so is the burn risk. Blisters and skin damage are reported. Any relief is likely the distraction of warmth, the same idea behind a mustard plaster. That is not a treatment for arthritis.
• Poor appetite and sluggish digestion: Pungent foods were long used to wake up appetite before a meal. This use is based on taste and custom. No human trials back it for horseradish. In some people the root does the opposite and causes heartburn or stomach pain.
• Scurvy, in historic sea voyages: Scurvy is caused by a lack of vitamin C, and vitamin C prevents and treats it. That part is settled science. Fresh horseradish does contain vitamin C, which is why it was carried at sea. That is a food fact, not a medicinal action of the root. Scurvy today is handled with vitamin C, not with horseradish.

Which foods are rich in Horseradish?

1. Fresh horseradish root
2. Prepared horseradish in vinegar
3. Horseradish cream and cocktail sauce
4. Most supermarket wasabi paste, which is usually horseradish

Practical Tips:

In food amounts, horseradish is a normal condiment for most healthy adults. The cautions on this page apply to medicinal amounts, capsules and skin poultices.

What are the side effects of Horseradish?

• Burning in the mouth, throat and nose
• Watering eyes and sneezing
• Heartburn and reflux
• Stomach pain, nausea or vomiting
• Diarrhoea, more likely with large amounts
• Skin redness, blistering or burns from poultices
• Allergic reaction, with rash, swelling or wheeze
• Possible thyroid effects with large, long-term intake

Good to know:

Mild burning and watering eyes are very common and short-lived. Most people shake them off in minutes.

The serious problems come from amount and from skin contact. Large helpings can cause real stomach pain and vomiting. Poultices can leave blisters that scar.

Allergy is uncommon but possible, mostly in people reactive to mustard or other cabbage-family plants. Swelling of the lips or throat, or trouble breathing, is an emergency.

How much Horseradish should you take?

• Recommended daily: Horseradish is mainly a food, so most people meet it in teaspoons, not doses. For reference only, not as advice for you: the German Commission E monograph lists around 20 g of fresh root a day for adults taking it internally. For skin products it sets a ceiling of about 2% mustard oil. Capsule labels often state 300 mg to 1 g of dried root per serving. Those figures describe what reference works and labels carry. They are not a plan for your body. Two hard limits apply whatever the label says. Never swallow horseradish essential oil. Never give the root as a medicine to a child under 4. If you are considering it as a remedy rather than a condiment, ask a doctor or pharmacist first.
• Best time of day: Time of day does not matter much. Some people find the burn worse last thing at night, because lying down can bring on reflux (acid rising into the throat). If that happens to you, keep it to earlier in the day.
• With or without food: Take it with food if you take it at all. An empty stomach makes burning, nausea and heartburn more likely. Eating it as part of a meal is both the traditional way and the gentler way.
• Time to effect: The nose-clearing hit is almost instant, within seconds of the vapour reaching you. It also fades within minutes. For anything else, there is no reliable timeline. Studies of the nasturtium combination ran for weeks. Be clear with yourself about this: for most claimed uses, horseradish may do nothing at all.
• How long to take it: As a food, horseradish needs no time limit for most healthy adults. Medicinal use is short-term by custom. Folk and monograph use runs for a few days during a cold, not for months. Long, heavy intake has not been studied for safety. Skin poultices are the opposite problem. Leaving one on for long causes burns. There is no safe duration this page can give, which is another reason to skip that form. If symptoms are not improving within a week, stop and get them looked at.