1. an organism that lives on or in an organism of another species, known as the host, from the body of which it obtains nourishment.
2. a person who receives support, advantage, or the like, from another or others without giving any useful or proper return, as one who lives on the hospitality of others.
These herbs might help rid you of the latter type of parasite (especially if you ask them to pay for it) but they are much more effective at clearing the former, specifically endoparasites, also known as helminths or more commonly; parasitic or intestinal worms. These little blighters feed off living hosts, receiving nourishment and protection while disrupting their host's nutrient absorption causing weakness and disease.
Modern pharmaceuticals will shift them but at the expense of unpleasant side effects such as headaches, nausea, abdominal pain, diarrhea and dizziness. Wormwood, Black Walnut Hull and Clove can do the same job; naturally.
Wormwood (from the Artemisia shrub - artemisia absinthum) is known for its vermicidal properties. It increases the acidity of the stomach and the production of bile. Wormwood capsules kill the larval stages parasites.
Black Walnut Hull's (from the black walnut tree - juglans nigra) active ingredients are juglone, tannin and iodine. Tincture made from the green hulls of the black walnut kills the adult stages of parasites.
Clove (from the clove tree - eugenia caryophyllata) has long been know to posses anti-parasitical, anti-fungal, antiviral and anti-inflammatory properties. It can even ease pain. Clove capsules remove parasite eggs.