Parasites are organisms larger than yeast or bacteria that can cause infection, usually in the intestines. The most common parasites to infect humans in the United States and Canada are giardia (Giardia lamblia), Entamoeba histolytica, cryptosporidium (Cryptosporidium spp.), roundworm (Ascaris lumbricoides), hookworm (Ancylostoma duodenale and Necator americanus), pinworm (Enterobius vermicularis), and tapeworm (Taenia spp.).
Infection with parasites can be life-threatening in people with severe impairment of immune function. People should consult a physician if they suspect a parasitic infection.
What are the symptoms of parasites?
Parasite infections can lead to a variety of symptoms, including gas, bloating, diarrhea, weight loss, abdominal cramping and pain, constipation, nausea, vomiting, loss of appetite, fever, rash, cough, itching anus, and bloody or foul-smelling stools.
Dietary changes that may be helpful for parasites
When traveling in developing countries, people should avoid drinking tap water and eating uncooked foods, foods prepared by street vendors, ice, and fruits that cannot be peeled. All of these are potential sources of parasitic infection. People should not drink untreated stream water while camping, as it is frequently almost invariably contaminated with giardia, even in the United States. Undercooked fish, meat and poultry can also contain parasites.
Nutritional supplements that may be helpful for parasites
Propolis is a resinous substance collected by bees from the leaf buds and bark of trees, especially poplar and conifer trees. The antimicrobial properties of propolis may help protect against parasitic infections in the gastrointestinal tract. One preliminary trial of propolis extract for children and adults with giardiasis showed a 52% rate of successful parasite elimination in children and a 60% elimination rate in adults (amount not stated).1 These results are not as impressive as those achieved with conventional drugs for giardiasis, though, so propolis should not be used as the sole therapy for parasites without first consulting a physician about available medical treatment.
Are there any side effects or interactions with parasites?
Refer to the individual supplement for information about any side effects or interactions.
Herbs that may be helpful for parasites
Berberine is derived from several plants, including barberry, Oregon grape, goldenseal, and goldthread (Coptis chinensis). Preliminary trials have shown that berberine can be used successfully to treat giardia infections.2 3 In addition, test tube studies show that berberine kills amoebae, although it is not known whether this effect occurs in humans.4 The amount required is approximately 200 mg three times per day for an adult—a level high enough to potentially cause side effects. Therefore, berberine should not be used without consulting a healthcare provider.
Emetine and other alkaloids in ipecac kill several types of parasites, including amoeba, pinworms, and tapeworms.5 6 Generally the amounts of ipecac needed to produce these effects in people are high and can lead to severe side effects. Emetine or its somewhat safer form, dihydroemetine, are reserved for rare cases of people infected with amoebae who are not cured by using anti-amoeba drugs.7 Because of the danger involved, ipecac and emetine should never be used without first consulting a physician.
In a preliminary trial, patients with schistosomiasis (a parasitic infection) were treated with a combination of resin and volatile oil of myrrh, in the amount of 10 mg per 2.2 pounds of body weight per day for three days. The cure rate was 91.7% and, of those who did not respond, 76.5% were cured by a second six-day course of treatment, increasing the overall cure rate to 98.1%.8
Garlic has been demonstrated to kill parasites, including amoeba9 and hookworm,10 in test tubes and in animals. Older studies in humans support the use of garlic to treat roundworm, pinworm, and hookworm.11 However, due to a lack of clinical trials, the amount of garlic needed to treat intestinal parasites in humans is not known.
Wormseed (Chenopodium ambrosioides) is a traditional remedy for infections with worms. However, a study in Mexico found that the powdered herb was not effective at eradicating hookworm, roundworm, or whipworm.12
Pumpkin seeds (Cucurbita pepo) have purported effects against tapeworms. Given their safety, they are often recommended as an addition to other, more reliable therapies. In Germany, 200–400 grams are commonly ground and taken with milk and honey, followed by castor oil two hours later.13 Tapeworms can cause severe illness and should be treated only with medical supervision. In China, pumpkin seeds have been shown to effectively treat acute schistosomiasis, a severe parasitic disease occurring primarily in Asia and Africa that is transmitted by snails.14 The assistance of a physician is required to help diagnose and treat any suspected intestinal parasite infection.
Several other herbs are traditionally used for treatment of parasites, including male fern (Dryopteris filix mas) root, tansy (Tanacetum vulgare) leaf, wormwood, sweet Annie, black walnut (Juglans nigra) fruit, and cloves (Syzygium aromaticum). Numerous case reports and preliminary studies from the late 1800s and early 1900s have suggested some of these herbs can be helpful for some parasitic infections.15
In some cultures, it was customary to bathe in chaparral once per year to eliminate skin parasites and to detoxify; however, there is no modern research demonstrating the effectiveness of this use of chaparral.
Anise may have modest antiparasitic actions and has been recommended by some practitioners as a treatment for mild intestinal parasite infections.16
Curled mint (Mentha crispa) leaf, a close relative of peppermint, has been shown in a preliminary trial to help relieve the symptoms of giardia and amoeba infections in children and adults, as well as to eliminate these parasites in many cases.17 This study used a tincture of curled mint in the amount of 2 ml three times per day for five days, or 1 ml three times per day for five days for children. Given their close relationship, peppermint could probably be substituted for curled mint when curled mint is unavailable.
Caution: Any herb potent enough to kill parasites could potentially harm the person taking it. Although some of these herbs have antiparasitic actions in test tubes,18 none has been adequately tested in modern trials for efficacy or safety in humans. Safe and proper use requires the skills of an experienced practitioner.
Are there any side effects or interactions with parasites?
Refer to the individual herb for information about any side effects or interactions.