Horsetail extract is most commonly used for removing excess water from the body and for strengthening bones, according to the University of Maryland Medical Center. Men and women also take this herbal supplement to help with kidney stones, urinary tract infections, brittle nails and minor wounds.
Little research has been done on the effectiveness of horsetail extract. UMMC warns that children should not take horsetail due to its nicotine content. Since Equisetum palustre is poisonous, only the horsetail type Equisetum arvense should be ingested. Other names for this herb include toadpipe, bottlebrush, horse willow, scouring rush, paddock pipes and shave grass.