Horsetail: MedlinePlus Supplements

T What is it?
P Horsetail is a plant. The above ground parts are used to make medicine.
P Horsetail is used for “fluid retention” (edema), kidney and bladder stones, urinary tract infections, the inability to control urination (incontinence), and general disturbances of the kidney and bladder.
P It is also used for balding; tuberculosis; jaundice; hepatitis; brittle fingernails; joint diseases; gout; osteoarthritis; weak bones (osteoporosis); frostbite; weight loss; heavy menstrual periods; and uncontrolled bleeding (hemorrhage) of the nose, lung, or stomach.
P Horsetail is applied directly to the skin to treat wounds and burns.
P There have been reports of horsetail products being contaminated with a related plant called Equisetum palustre. This plant contains chemicals that can poison cattle, but toxicity in people has not been proven.

T How effective is it?
P Natural Medicines Comprehensive Database rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, Ineffective, and Insufficient Evidence to Rate.
P The effectiveness ratings for HORSETAIL are as follows:
t Insufficient evidence to rate effectiveness for...
- Osteoporosis. Early research suggests that taking dry horsetail extract or a specific product containing horsetail extract plus calcium (Osteosil Calcium) by mouth can increase bone density in postmenopausal women with osteoporosis.
- Kidney and bladder stones.
- Weight loss.
- Hair loss.
- Gout.
- Frostbite.
- Heavy periods.
- Fluid retention.
- Urinary tract infections.
- Incontinence.
- Use on the skin for wound healing.
- Other conditions.
P More evidence is needed to rate the effectiveness of horsetail for these uses.

T How does it work?
P The chemicals in horsetail may have antioxidant and anti-inflammatory effects. Plants related to horsetail contain chemicals that work like "water pills" (diuretics) and increase urine output. But it isn't clear whether horsetail has this effect.

T Are there safety concerns?
P Horsetail is POSSIBLY UNSAFE when taken by mouth long-term. It contains a chemical called thiaminase, which breaks down the vitamin thiamine. In theory, this effect could lead to thiamine deficiency. Some products are labeled "thiaminase-free," but there is not enough information available to know if these products are safe.
t Special precautions & warnings:
P Pregnancy and breast-feeding: There is not enough reliable information about the safety of taking horsetail if you are pregnant or breast-feeding. Stay on the safe side and avoid use.
P Alcoholism: People who are alcoholics are generally also thiamine deficient. Taking horsetail might make thiamine deficiency worse.
P Diabetes: Horsetail might lower blood sugar levels in people with diabetes. Watch for signs of low blood sugar (hypoglycemia) and monitor your blood sugar carefully if you have diabetes and use horsetail.
P Low potassium levels (hypokalemia): Horsetail might flush potassium out of the body, possibly leading to potassium levels that are too low. Until more is known, use horsetail with caution if you are at risk for potassium deficiency.
P Low thiamine levels (thiamine deficiency): There is a concern that horsetail could make thiamine deficiency worse.

T Are there interactions with medications?
P Moderate
P Be cautious with this combination.
P Lithium
P Horsetail might have an effect like a water pill or "diuretic." Taking horsetail might decrease how well the body gets rid of lithium. This could increase how much lithium is in the body and result in serious side effects. Talk with your healthcare provider before using this product if you are taking lithium. Your lithium dose might need to be changed.
P Medications for diabetes (Antidiabetes drugs)
P Horsetail might decrease blood sugar in people with type 2 diabetes. Diabetes medications are also used to lower blood sugar. Taking horsetail along with diabetes medications might cause your blood sugar to go too low. Monitor your blood sugar closely. The dose of your diabetes medication might need to be changed.
P Some medications used for diabetes include glimepiride (Amaryl), glyburide (DiaBeta, Glynase PresTab, Micronase), insulin, pioglitazone (Actos), rosiglitazone (Avandia), chlorpropamide (Diabinese), glipizide (Glucotrol), tolbutamide (Orinase), and others.
P Water pills (Diuretic drugs)
P Large amounts of horsetail might decrease potassium levels in the body. "Water pills" can also decrease potassium in the body. Taking horsetail along with "water pills" might decrease potassium in the body too much.
P Some "water pills" that can deplete potassium include chlorothiazide (Diuril), chlorthalidone (Thalitone), furosemide (Lasix), hydrochlorothiazide (HCTZ, HydroDiuril, Microzide), and others.

T Are there interactions with herbs and supplements?
P Areca
P Horsetail and areca both reduce the amount of thiamine that the body has to use. Using these herbs together raises the risk that the amount of thiamine will become too low.
P Chromium-containing herbs and supplements
P Horsetail contains chromium (0.0006%) and could increase the risk of chromium poisoning when taken with chromium supplements or chromium-containing herbs such as bilberry, brewer's yeast, or cascara.
P Herbs and supplements that might lower blood sugar
P Horsetail might lower blood sugar. Using it along with other herbs and supplements that have the same effect might cause blood sugar to drop too low in some people. Some of these products include alpha-lipoic acid, bitter melon, chromium, devil's claw, fenugreek, garlic, guar gum, horse chestnut, Panax ginseng, psyllium, Siberian ginseng, and others.
P Thiamine
P Crude horsetail contains thiaminase, a chemical that breaks down thiamine. Cattle that eat a lot of horsetail have developed thiamine deficiency.

T Are there interactions with foods?
P There are no known interactions with foods.

T What dose is used?
P The appropriate dose of horsetail depends on several factors such as the user’s age, health, and several other conditions. At this time there is not enough scientific information to determine an appropriate range of doses for horsetail. Keep in mind that natural products are not always necessarily safe and dosages can be important. Be sure to follow relevant directions on product labels and consult your pharmacist or physician or other healthcare professional before using.

T Other names
P Asprêle, Bottle Brush, Cavalinha, Coda Cavallina, Cola de Caballo, Common Horsetail, Corn Horsetail, Dutch Rushes, Equiseti Herba, Equisetum, Equisetum arvense, Equisetum hyemale, Equisetum telmateia, Field Horsetail, Herbe à Récurer, Horse Herb, Horsetail Grass, Horsetail Rush, Horse Willow, Paddock-Pipes, Pewterwort, Prele, Prêle, Prêle Commune, Prêle des Champs, Queue-de-Chat, Queue-de-Cheval, Queue-de-Rat, Queue-de-Renard, Scouring Rush, Souring Rush, Shave Grass, Shavegrass, Spring Horsetail, Toadpipe.

T Methodology
P To learn more about how this article was written, please see the Natural Medicines Comprehensive Database methodology.

T References
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