The information provided here is not a replacement for a doctor. You shouldn't use it for the purpose of self-diagnosing or self-medicating but rather so you can have a more informed discussion with a professional TCM practitioner.
Because it is a herb specifically indicated to treat taeniasis as can be seen on Areca Nut's page.
Areca Nuts is a Warm herb that tastes Bitter and Pungent. It targets the Large intestine and the Stomach.
Its main actions are: Destroys parasites. Regulates Qi circulation. Promotes urination.
Intestinal parasites Ascariasis Fasciolopsiasis Abdominal pain Diarrhea Edema Malaria