Black Walnut

• Consider taking black walnut. Black walnut, available at any herbal or natural products store, is a natural antidiarrhetic. This bitter herb also happens to be a natural fighter of parasites, making it doubly ideal for combating giardiasis. Black walnut soothes and cools the intestines, calming gastrointestinal irritation. When traveling to places where the water or the food may contain parasites like giardia, black walnut may be your best answer for preventing and treating all of the symptoms of giardiasis--nausea, diarrhea and abdominal pains. The herb should be taken as a tincture.
  
  

Sweet Annie

• Sweet Annie--also known as Qing Hao by Chinese herbalists (as it originates in China)--has long been used to treat parasite-induced sicknesses like malaria and giardiasis. This herb, available from any herbal store or natural products store, can be taken as a powder (mixed with water) or a tablet. Avoid Sweet Annie if you are pregnant.
  
  

Quassia

• You may want to try quassia, an antiparasitic herb available from any herbal or natural products store in either tincture or capsule form. Quassia, a bitter herb, is typically used to treat gastrointestinal problems like loss of appetite, worms and, of course, giardia. Quassia helps your body attack and quickly rid itself of the giardia parasite.