Horseradish

Armoracia rusticana
Family: Cruciferae

If you are allergic to or sensitive to cabbage, broccoli, or brussels sprouts you may have that same sensitivity for horseradish.

Horseradish is generally used as a seasoning. In large amounts it can cause internal problems and/or irritation of the nose and throat lining rather like any other strong herb. That strong taste is a concentrated dose of natural chemicals that protect the plant from the depredations of herbivores, so eating the top (greens) is not recommended. Horseradish contains coumarins, phenols, volatile oils, ascorbic acid, asparagin, peroxidase enzymes and other chemicals as well. It prevents the breakdown and absorption of alcohol and some other substances. It stimulates digestion and blood circulation so it may be used in situations where people have circulation problems.

It is used for clearing the sinuses (for obvious reasons) which makes it useful for mild allergic reactions such as a pollen reaction when a stuffy nose is the main symptom. It is an expectorant with strong anti-biotic properties. It is also used to expel worms in pets (vermifuge) and for fevers. There are a number of different chemicals in horseradish, some of which interact and cancel each other out.

My drug interaction book says to avoid anticholinergic as well as cholinergic drugs when using horseradish, but I wasn't able to find any information as to whether it cancels out or enhances the effects of these drugs. It also should not be taken by anyone with an underactive thyroid.