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Medical Disclaimer: This information is for educational purposes only and is not a substitute for professional medical advice.
Non-Standardized Food Allergenic Extract [EPC]
Horseradish is a member of the Brassicaceae family, utilized clinically as a non-standardized food allergenic extract for the diagnosis and treatment of IgE-mediated hypersensitivity, as well as for its traditional phytochemical properties.
Name
Horseradish
Raw Name
HORSERADISH
Category
Non-Standardized Food Allergenic Extract [EPC]
Drug Count
6
Variant Count
6
Last Verified
February 17, 2026
About Horseradish
Horseradish is a member of the Brassicaceae family, utilized clinically as a non-standardized food allergenic extract for the diagnosis and treatment of IgE-mediated hypersensitivity, as well as for its traditional phytochemical properties.
Detailed information about Horseradish
References used for this content
This page is for informational purposes only and does not replace medical advice. Consult a qualified healthcare professional before using any medication containing Horseradish.
Horseradish (Armoracia rusticana) is a perennial plant belonging to the Brassicaceae family, which also includes mustard, wasabi, broccoli, and cabbage. While widely recognized as a pungent culinary condiment, in a clinical and pharmacological context, Horseradish is classified by the FDA as a Non-Standardized Food Allergenic Extract [EPC]. This classification encompasses its use as a biological agent for the diagnosis and, in specific cases, the immunotherapy of allergic sensitivities. Horseradish extracts are complex mixtures of proteins, glycoproteins, and polysaccharides derived from the raw plant material.
As a non-standardized extract, Horseradish does not have a defined potency unit (like Bioequivalent Allergy Units) but is instead prepared according to weight/volume (w/v) or PNU (Protein Nitrogen Unit) ratios. It belongs to a broader class of drugs known as allergenic extracts, which are used by allergists to identify specific triggers of Type I hypersensitivity reactions. Beyond its use as an allergen, Horseradish contains significant concentrations of glucosinolates, specifically sinigrin, which is converted into allyl isothiocyanate (AITC) upon tissue disruption. This compound is responsible for the plant's characteristic heat and has been studied for its antimicrobial, anti-inflammatory, and potential chemopreventive properties. The FDA has regulated allergenic extracts under the Public Health Service Act, and while many food extracts have been in use for decades, they are subject to ongoing review for safety and diagnostic efficacy.
The mechanism of Horseradish depends entirely on its application—whether as a diagnostic allergen or a phytochemical agent.
When used as a diagnostic tool (e.g., skin prick testing), Horseradish extract works by eliciting a localized Type I hypersensitivity reaction. In patients sensitized to Horseradish, specific Immunoglobulin E (IgE) antibodies are bound to the surface of mast cells and basophils. When the Horseradish proteins (the antigens) are introduced into the skin, they cross-link these IgE molecules. This cross-linking triggers degranulation, releasing inflammatory mediators such as histamine, leukotrienes, and prostaglandins. This results in the 'wheal and flare' reaction—a raised bump surrounded by redness—which allows the healthcare provider to confirm an allergy.
At a molecular level, the primary active constituent is sinigrin. When Horseradish is crushed, the enzyme myrosinase comes into contact with sinigrin, hydrolyzing it into allyl isothiocyanate (AITC). AITC acts on the Transient Receptor Potential Ankyrin 1 (TRPA1) and Vanilloid 1 (TRPV1) receptors located on sensory nerve endings in the mucous membranes. This stimulation causes the immediate 'clearing' sensation in the sinuses and may stimulate mucus secretion (secretolytic effect), which is why it has been used traditionally for respiratory conditions. Furthermore, AITC has been shown in laboratory settings to inhibit the growth of certain bacteria by disrupting cell membrane integrity and inhibiting essential enzyme systems.
The pharmacokinetics of Horseradish as an allergenic extract differ significantly from traditional oral medications because the extract is typically administered epicutaneously (on the skin) or intradermally.
> Important: Only your healthcare provider can determine if Horseradish extract or related products are right for your specific diagnostic or therapeutic needs. Clinical testing must always be performed in a facility equipped to handle anaphylaxis.
For skin prick testing (SPT), a single drop of the 1:20 w/v or 1:10 w/v extract is applied to the volar surface of the forearm or the back. A sterile lancet is used to prick the skin through the drop. A positive control (histamine) and a negative control (saline/glycerin) are administered simultaneously. The results are read after 15 to 20 minutes.
In jurisdictions where Horseradish is approved for respiratory or urinary tract infections, the typical adult dosage of a standardized preparation (often combined with Nasturtium herb) is approximately 200 mg to 500 mg taken 3 to 5 times daily. The total daily dose should not exceed the recommendations provided by the specific product manufacturer or the prescribing physician.
Pediatric skin testing follows the same protocol as adults, though the number of skin pricks may be limited to reduce distress. It should only be performed by a pediatric allergist.
Horseradish-based medications are generally not recommended for children under the age of 4 due to the potential for gastrointestinal irritation and the lack of robust safety data in this age group. For children aged 4 to 12, dosages are typically reduced (e.g., half the adult dose), but this must be directed by a pediatrician.
Because the metabolites of Horseradish (isothiocyanates) are excreted renally, individuals with significant renal impairment (CrCl < 30 mL/min) should exercise caution. While specific dose adjustments are not standardized, a reduction in frequency may be warranted to prevent accumulation of metabolites.
Since the metabolism of AITC involves glutathione conjugation in the liver, patients with severe hepatic impairment or depleted glutathione levels (e.g., chronic malnutrition or acetaminophen toxicity) may be at higher risk for adverse effects. Use should be monitored closely.
No specific dosage adjustment is required for diagnostic testing. For oral use, providers should consider the higher prevalence of gastrointestinal sensitivity and renal decline in the elderly population.
If Horseradish is being taken as a supplement and a dose is missed, take it as soon as remembered. If it is almost time for the next dose, skip the missed dose and resume the regular schedule. Do not double the dose to catch up.
Signs of an oral overdose include severe abdominal pain, vomiting, diarrhea (sometimes bloody), and excessive salivation. In the case of diagnostic testing, an 'overdose' or extreme sensitivity manifests as a systemic allergic reaction (anaphylaxis).
Emergency Measures:
> Important: Follow your healthcare provider's dosing instructions exactly. Do not adjust your dose or initiate use without professional medical guidance.
> Warning: Stop using Horseradish and call your doctor or emergency services immediately if you experience any of the following:
Prolonged use of high-dose Horseradish supplements may lead to chronic gastritis (inflammation of the stomach lining). There is also a theoretical risk of 'isothiocyanate-induced' interference with thyroid function in patients who are already iodine-deficient, potentially leading to goiter or hypothyroidism. However, data on this specifically for Horseradish is limited compared to other cruciferous vegetables.
No FDA black box warnings specifically for Horseradish as a food extract. However, all Allergenic Extracts carry a general class warning regarding the risk of severe systemic allergic reactions.
Summary of Class Warning: Allergenic extracts can cause severe life-threatening systemic reactions, including anaphylaxis. They should only be administered by healthcare professionals prepared to manage such reactions. Patients with unstable asthma are at increased risk for severe outcomes. Patients must be observed for at least 30 minutes following administration.
Report any unusual symptoms or persistent side effects to your healthcare provider. You may also report side effects to the FDA at 1-800-FDA-1088.
Horseradish is generally recognized as safe (GRAS) when consumed in culinary amounts. However, its use as a concentrated extract or medicinal supplement requires significant caution. The most critical safety concern is the risk of an undiagnosed allergy, which can lead to anaphylaxis upon exposure to concentrated forms.
As of 2026, there are no specific FDA black box warnings for Horseradish. However, as noted in the side effects section, it falls under the general safety mandates for all allergenic extracts. These mandates require administration in clinical settings equipped with resuscitation equipment and trained personnel.
Horseradish does not typically cause sedation or cognitive impairment. However, if a systemic allergic reaction occurs, or if severe lacrimation (tearing) is triggered by the pungent vapors, driving or operating machinery may be hazardous. Patients should ensure their vision is clear and they feel stable before such activities.
Alcohol may increase the risk of gastric irritation when combined with Horseradish. Furthermore, alcohol can potentially enhance the absorption of certain phytochemicals or, conversely, worsen the symptoms of an allergic reaction by causing vasodilation. It is generally advised to limit alcohol consumption when using Horseradish therapeutically.
There is no known withdrawal syndrome associated with the discontinuation of Horseradish. However, if being used for a respiratory infection, stopping the treatment prematurely may result in a return of symptoms. If an allergic reaction occurs, the substance must be discontinued immediately and never reused.
> Important: Discuss all your medical conditions, especially gastrointestinal or thyroid issues, with your healthcare provider before starting Horseradish.
> Important: Tell your doctor about ALL medications, supplements, and herbal products you are taking before undergoing allergy testing or starting Horseradish supplements.
Individuals allergic to the following substances may exhibit cross-reactivity with Horseradish:
This cross-sensitivity occurs because these plants share similar storage proteins and enzymes (like myrosinase) that the immune system recognizes as identical or highly similar.
> Important: Your healthcare provider will evaluate your complete medical history, including any history of asthma or stomach issues, before prescribing or administering Horseradish.
There are no adequate and well-controlled studies of Horseradish extract in pregnant women. Culinary use is considered safe. However, medicinal doses or allergenic testing should be avoided unless the potential benefit outweighs the risk to the fetus. The primary concern is not direct teratogenicity but the risk of maternal anaphylaxis, which can cause fetal hypoxia (lack of oxygen) and distress. Initiation of allergy shots (immunotherapy) is generally not recommended during pregnancy.
It is not known whether the constituents of Horseradish or their metabolites are excreted in human milk. Allyl isothiocyanate is small and lipophilic, suggesting passage is possible. While culinary amounts are unlikely to affect a nursing infant, medicinal doses might cause colic or irritability in the baby. Use with caution and monitor the infant for gastrointestinal distress.
Horseradish is approved for diagnostic allergy testing in children under the supervision of an allergist. As a therapeutic agent, it is generally contraindicated in children under 4 years of age. In older children, it should be used sparingly, as they are more susceptible to the irritating effects on the gastric and respiratory mucosa. There is no evidence that Horseradish affects growth or development when used appropriately.
Older adults may have a higher risk of adverse effects from Horseradish. Age-related declines in renal function (GFR) may lead to slower clearance of isothiocyanate metabolites. Furthermore, the elderly are more likely to be on medications like beta-blockers or ACE inhibitors, which complicate the safety profile of Horseradish extracts. Providers should also consider the risk of 'silent' gastric irritation in patients who may also be taking NSAIDs for arthritis.
In patients with moderate to severe renal impairment, the excretion of the mercapturic acid conjugates of Horseradish is delayed. While no specific GFR-based dosing exists, clinical monitoring for signs of systemic toxicity (e.g., unusual irritation or hematuria) is necessary. It is not known if Horseradish metabolites are cleared by hemodialysis.
Patients with Child-Pugh Class B or C hepatic impairment may have reduced glutathione levels, which are essential for neutralizing allyl isothiocyanate. This could potentially increase the systemic half-life of the active pungent compounds, leading to increased side effects. Use should be approached with extreme caution in this population.
> Important: Special populations require individualized medical assessment and should never self-treat with Horseradish extracts.
Horseradish acts through two distinct pathways depending on the context of use:
| Parameter | Value |
|---|---|
| Bioavailability | >80% (for AITC) |
| Protein Binding | Moderate (primarily to Albumin) |
| Half-life | 2 - 8 hours (metabolites) |
| Tmax | 1.5 - 3 hours (oral ingestion) |
| Metabolism | Hepatic (Glutathione conjugation) |
| Excretion | Renal (>90% as mercapturic acids) |
Horseradish is classified as a Non-Standardized Food Allergenic Extract. It shares this class with other diagnostic extracts like Mustard, Rye, and Wheat extracts. In a phytotherapeutic context, it is often grouped with other Isothiocyanate-yielding botanicals.
Common questions about Horseradish
Clinically, Horseradish is primarily used as a non-standardized allergenic extract to diagnose food allergies through skin prick testing. In some regions, it is also used in standardized oral forms to help treat symptoms of sinusitis, bronchitis, and urinary tract infections due to its natural antimicrobial and mucus-thinning properties. It contains compounds called glucosinolates that, when activated, can help clear respiratory passages. However, these uses should always be overseen by a healthcare professional to ensure safety and proper dosing. It is not a substitute for antibiotics when they are clinically indicated.
The most common side effects include a burning sensation in the mouth, throat, or stomach, and watery eyes (lacrimation) or a runny nose. When used in skin testing, it typically causes a localized itchy red bump (wheal) at the site of the prick, which is the expected diagnostic result. Some people may also experience nausea, indigestion, or mild abdominal cramping after taking oral supplements. These effects are usually temporary and related to the plant's pungent natural oils. If these symptoms persist or become severe, you should contact your doctor.
It is generally recommended to avoid or significantly limit alcohol while taking medicinal amounts of Horseradish. Alcohol can irritate the stomach lining, which may worsen the gastric discomfort often caused by Horseradish's pungent isothiocyanates. Additionally, alcohol can cause vasodilation, which might theoretically worsen the symptoms of an allergic reaction if one were to occur. Always consult your healthcare provider about your alcohol consumption when starting a new medication or supplement. Safety is the priority, especially if you have a history of gastritis or ulcers.
Horseradish is considered safe when consumed in normal culinary amounts during pregnancy. However, medicinal extracts or high-dose supplements are generally avoided because there is insufficient data to guarantee their safety for the developing fetus. The biggest concern is the risk of a severe allergic reaction (anaphylaxis) in the mother, which could dangerously reduce the oxygen supply to the baby. Because of these risks, most doctors advise against starting Horseradish allergy testing or intensive supplementation while pregnant. Always discuss any herbal or dietary changes with your obstetrician.
The timing depends on the form and the reason for use. In diagnostic skin testing, the reaction (a wheal and flare) usually appears within 15 to 20 minutes of the skin prick. For clearing the sinuses or respiratory passages, the effects of the volatile oils are often felt almost immediately or within a few minutes of consumption. If taken as a supplement for a urinary tract or respiratory infection, it may take 24 to 48 hours of regular dosing to notice a significant improvement in symptoms. Always follow the specific timeline provided by your healthcare professional.
Yes, Horseradish can typically be stopped suddenly without risk of withdrawal symptoms or physical dependence. It is not a habit-forming substance. However, if you are taking it to treat a specific condition like sinusitis, stopping too early may cause your symptoms to return. If you are stopping because of a suspected allergic reaction or severe stomach pain, you should do so immediately and inform your doctor. Always complete the course of treatment recommended by your provider unless you experience adverse effects.
If you miss a dose of a Horseradish supplement, take it as soon as you remember. However, if it is nearly time for your next scheduled dose, skip the missed one and continue with your regular routine. Do not take two doses at once to make up for the one you missed, as this increases the risk of stomach irritation and other side effects. If you are unsure what to do, call your pharmacist or doctor for guidance. Consistency is helpful for therapeutic effects, but safety should always come first.
There is no clinical evidence to suggest that Horseradish causes weight gain. In fact, because it is often used as a low-calorie condiment, it is unlikely to contribute to weight issues. Some preliminary research in animals has even explored whether the active compounds in Horseradish might support metabolism, but this has not been proven in humans. If you experience sudden weight gain or swelling while taking any supplement, you should consult your doctor, as this could be a sign of an underlying health issue or a different reaction. Horseradish itself is not associated with adiposity.
Horseradish can interact with several types of medications, so caution is necessary. It may interfere with the effectiveness of thyroid medications or increase the risk of bleeding if taken with blood thinners like Warfarin or Aspirin. It can also interfere with the results of allergy skin tests if you are taking antihistamines or certain antidepressants. Most importantly, it should be used cautiously if you are on beta-blockers or ACE inhibitors, as these can complicate the treatment of an allergic reaction. Always provide your doctor with a full list of your current medications before starting Horseradish.
Horseradish is a natural substance, so it is not 'patented' in the way synthetic drugs are. It is available from various manufacturers as a non-standardized allergenic extract and as a dietary supplement. In the context of allergy testing, different biological laboratories produce their own versions of the extract. While they are not 'generics' in the traditional pharmaceutical sense, they are equivalent tools used by allergists. Always ensure you are using a product from a reputable source that follows Good Manufacturing Practices (GMP).