Overview

Horsetail refers to various plant species of the Equisetum genus. It may help reduce fluid retention, but might cause vitamin B1 deficiency when used long-term.

The chemicals in horsetail might have antioxidant and anti-inflammatory effects. They might also work like "water pills" (diuretics) and increase urination.

People use horsetail for fluid retention, urinary tract infections (UTIs), osteoporosis, loss of bladder control, and many other conditions, but there is no good scientific evidence to support these uses.

Uses & Effectiveness

We currently have no information for Horsetail overview.

Side Effects

When taken by mouth: It is possibly unsafe to take horsetail products that contain thiaminase. Thiaminase breaks down the vitamin thiamine. This could lead to thiamine deficiency. Some horsetail products are labeled "thiaminase-free," but there isn't enough reliable information to know if these products are safe or what the side effects might be.

When applied to the skin: There isn't enough reliable information to know if horsetail is safe or what the side effects might be.

Special Precautions and Warnings

When taken by mouth: It is possibly unsafe to take horsetail products that contain thiaminase. Thiaminase breaks down the vitamin thiamine. This could lead to thiamine deficiency. Some horsetail products are labeled "thiaminase-free," but there isn't enough reliable information to know if these products are safe or what the side effects might be.

When applied to the skin: There isn't enough reliable information to know if horsetail is safe or what the side effects might be.

Pregnancy and breast-feeding: There isn't enough reliable information to know if horsetail is safe to use when pregnant or breast-feeding. Stay on the safe side and avoid use.

Alcohol use disorder: People with this condition are generally also thiamine deficient. Taking horsetail might make thiamine deficiency worse.

Allergies to carrots and nicotine: Some people with allergy to carrot might also have allergy to horsetail. Horsetail also contains small amounts of nicotine. People with nicotine allergy might have an allergic reaction to horsetail.

Low potassium levels (hypokalemia): Horsetail might lower potassium levels in the blood. Until more is known, use horsetail with caution if you are at risk for potassium deficiency.

Low thiamine levels (thiamine deficiency): Taking horsetail might make thiamine deficiency worse.

Interactions

    Moderate Interaction

    Be cautious with this combination

  • Lithium interacts with Horsetail

    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.

  • Efavirenz (Sustiva) interacts with Horsetail

    Efavirenz is a drug used to treat HIV. Taking horsetail with efavirenz might reduce the effects of efavirenz. Talk with your healthcare provider before using horsetail if you are taking efavirenz.

  • Medications for HIV/AIDS (Nucleoside reverse transcriptase inhibitors (NRTIs)) interacts with Horsetail

    Taking horsetail with NRTIs might reduce the effects of these drugs. Talk with your healthcare provider before using horsetail if you are taking an NRTI.

  • Medications for diabetes (Antidiabetes drugs) interacts with Horsetail

    Horsetail might lower blood sugar levels. Taking horsetail along with diabetes medications might cause blood sugar to drop too low. Monitor your blood sugar closely.

  • Water pills (Diuretic drugs) interacts with Horsetail

    Horsetail can decrease potassium levels. "Water pills" can also decrease potassium levels. Taking horsetail along with "water pills" might make potassium levels drop too low.

Dosing

There isn't enough reliable information to know what an appropriate dose of horsetail might be. 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 a healthcare professional before using.
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CONDITIONS OF USE AND IMPORTANT INFORMATION: This information is meant to supplement, not replace advice from your doctor or healthcare provider and is not meant to cover all possible uses, precautions, interactions or adverse effects. This information may not fit your specific health circumstances. Never delay or disregard seeking professional medical advice from your doctor or other qualified health care provider because of something you have read on WebMD. You should always speak with your doctor or health care professional before you start, stop, or change any prescribed part of your health care plan or treatment and to determine what course of therapy is right for you.

This copyrighted material is licensed from Therapeutic Research Center, LLC. Information from this source is evidence-based and objective, and without commercial influence. For professional medical information on natural medicines, see Natural Medicines Comprehensive Database Professional Version.
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