Horsetail is used to treat many conditions including osteoporosis, urinary tract infections, kidney stones, menstruation, fluid retention and burns, rheumatic disease and brittle nails. Regardless of why you're considering its use, horsetail can pose dangerous risks for people with thyroid dysfunction. If you have a thyroid condition consult a doctor before taking this herb.
Thyroid Medication Interaction
Horsetail may interact with thyroid medications by interfering with their effectiveness, according to “Let’s Get Natural With Herbs,” by Debra Rayburn. Horsetail also may interact with lithium, nicotine patches and gum, digoxin, diabetes medicines and diuretics.
Potassium Depletion
Horsetail can lower levels of potassium in your body. Be especially careful of this effect if you have hyperthyroidism, a condition in which your body makes too much thyroid hormone. The condition called thyrotoxic periodic paralysis, which causes sudden onset weakness, is associated with hypokalemia, or low potassium levels, in hyperthyroid patients, notes a 2011 “BMJ Case Reports” article. This condition is most likely to affect you if you are a hyperthyroid patient of Asian descent, but has been seen among people of all races. It’s also more likely to affect you if you are male, notes “Pediatric Endocrinology,” by Fima Lifshitz, M.D. Symptoms may range from mild weakness to total paralysis.
Thiamine Deficiency
Horsetail also may cause thiamine deficiency. Hyperthyroidism can increase your need for this nutrient and also may lead to thiamine, or vitamin B-1 deficiency, according to “Ophthalmic Oncology." Thiamine is an important coenzyme that helps your body metabolize fats, carbohydrates and some amino acids. Deficiency can cause loss of feeling in your hands and feet, difficulty walking, loss of muscle function in your legs, mental confusion, tingling, strange eye movements, pain and vomiting. Drinking alcohol and taking horsetail raise your risk for thiamine deficiency.
Considerations
According to MedlinePlus, there is not enough scientific evidence to rate horsetail as effective or ineffective for any use. It’s approved by Germany’s Commission E, that country’s regulatory body for herbs, for treating kidney and bladder stones, urinary tract infections and for treating wounds and burns. Using horsetail for a prolonged period is not recommended, according to University of Maryland Medical Center.
References
- University of Maryland Medical Center; Horsetail; March 2009
- MedlinePlus; Horsetail; July 2011
- “The Essential Herb-Drug-Vitamin Interaction Guide”; George T. Grossberg and Barry Fox; 2007
- “Let’s Get Natural With Herbs”; Debra Rayburn; 2007
- “Ophthalmic Oncology”; 2011
- “Pediatric Endocrinology”; Fima Lifshitz, M.D.; 2007
- PubMed Health; Hyperthyroidism; April 2010
- PubMed Health; Beriberi; July 2010
