Few side effects are linked to horseradish when it is taken in small doses. Side effects of horseradish can include irritation and burning of the mouth, throat, and stomach. Fresh horseradish can also cause skin irritation or an allergic reaction on contact or if inhaled.
Horseradish in large doses can cause stomach upset, bloody vomiting, diarrhea, and irritation to the urinary tract. See your doctor if you have heartburn or if you are taking antacids.
Horseradish may lower blood pressure and should be used with caution if you have low blood pressure or are taking medications that can lower blood pressure.
Horseradish may also affect thyroid hormone levels in the blood. See your doctor if you have a thyroid condition or if you are taking thyroid replacement medications.
The following medications may be affected by horseradish:
- ASA (Aspirin®)
- antiplatelets (e.g., clopidogrel, dipyridamole, ticlopidine)
- blood pressure medications
- diureticdiuretican agent that increases urine flows (e.g., furosemide, hydrochlorothiazide)
- nonsteroidal anti-inflammatory drugs (NSAIDs; e.g., ibuprofen, naproxen)
- thyroid medication (e.g., levothyroxine)
- blood thinners (e.g., warfarin, heparin)
- agents with cholinergic or anticholinergic effects (e.g., atropine, pyridostigmine)
Horseradish may also affect herbs with blood-thinning properties, such as:
- panax ginseng
- red clover
You should avoid horseradish if you are pregnant, have stomach or intestinal problems (e.g., ulcers, stomach inflammation), or have kidney disease. Do not use horseradish if you are allergic to it or to any plants from the Brassicaceae family.
Horseradish in large amounts may be unsafe during breast-feeding. See your doctor prior to taking horseradish if you are breast-feeding.
Contact your doctor if any of the symptoms or conditions being treated by horseradish persist or worsen.
Before taking any new medications, including natural health products, speak to your physician, pharmacist or other health care provider. Tell your health care practitioner about any natural health products you may be taking.