There still haven’t been any cases of poisoning because of the therapeutic use of field horsetail (Equisetum Arvense L.). But you have to make sure to take the right equisetum variety because there are other members of its family which look alike and are very toxic; as is the case of Equisetum palustre.

Horsetail Contraindications

Internal use of horsetail is not recommended during pregnancy or breastfeeding, because there aren’t any conclusive studies that exclude any side effects on fetuses or newborns. Its use is also not recommended for children.

Do not take if you:

dry horsetail image
  • Suffer gastritis, heartburn or stomach ulcers.
  • Have group II diabetes.
  • Have edema due to a heart or kidney failure.
  • Have a vitamin B1 deficiency.
  • Are prone to low potassium levels.
  • Have hypotension or heart problems.
  • Are nicotine sensitive or using patches.
  • Have alcoholism problems.
  • Are taking medicines like aspirins or anti-inflammatory drugs.
  • Are taking laxatives or diuretics.
  • Have ingested too much alcohol or irritants like spicy food.

Before starting any treatment with horsetail, it is always advisable to consult a doctor to avoid any improper use.

Side effects

  • Consuming large amounts of horsetail can be toxic and cause symptoms like: fever, irregular heartbeat and muscle weakness. Other side effects may occur when combining it with other medicines or dietary supplements, you should always check with your doctor before starting a treatment.
  • It is advised to take horsetail for no longer than 6 consecutive weeks. Prolonged use can lead to headache, loss of appetite, digestive problems and nervous disorders.
  • Field horsetail is very toxic for animals. It should never be given to them because it can even lead to death. After consuming this herb they may have: fever, digestive problems and breathing difficulties.

This website’s content is for information purposes only and in no way replaces the advice of a health professional. does not take any responsibility for the consequences caused by self-medication.