Signs and Symptoms
Parasites can live in the intestines for years without causing symptoms. When they do, symptoms include the following:

Abdominal pain
Diarrhea
Nausea or vomiting
Gas or bloating
Dysentery (loose stools containing blood and mucus)
Rash or itching around the rectum or vulva
Stomach pain or tenderness
Feeling tired
Weight loss
Passing a worm in your stool
What Causes It?
These things raise your risk for getting intestinal parasites:

Living in or visiting an area known to have parasites
International travel
Poor sanitation (for both food and water)
Poor hygiene
Age. Children and the elderly are more likely to get infected.
Exposure to child and institutional care centers
Having a weakened immune system
HIV or AIDS
What to Expect at Your Doctor’s Office
Your doctor will ask if you have traveled out of the country recently and whether you have recently lost weight. If your doctor thinks you have an intestinal parasite, you will probably have one or more of the following tests:

Fecal testing (examination of your stool) can identify both helminths and protozoa. Stool samples must be collected before you take any anti-diarrhea drugs or antibiotics, or before x-rays with barium are taken. Several stool samples may be needed to find the parasite.
The “Scotch tape” test identifies pinworms by touching tape to the anus several times, then looking at the tape under a microscope for eggs.
Your doctor may use x-rays with barium to diagnose more serious problems caused by parasites, although this test is usually not required.
Treatment Options
Drug Therapies
Your doctor will choose the drug that is most effective against your intestinal parasite. You may need one dose, or you may have to take the medication for several weeks. Be careful to take the medicine exactly as it is prescribed, or it may not work.

Complementary and Alternative Therapies
Conventional medical treatments can get rid parasites more quickly and with fewer side effects than most alternative treatments. Alternative treatments may be helpful along with conventional medications. However, your doctor must find out what kind of organism is causing your problems before you start treatment. The following nutritional guidelines may help keep parasites from growing.

Nutrition and Supplements
Avoid simple carbohydrates, such as those found in refined foods, fruits, juices, dairy products, and all sugars, except honey.
Eat more raw garlic, pumpkin seeds, pomegranates, beets, and carrots, all of which have been used traditionally to kill parasites. In one study, researchers found that a mixture of honey and papaya seeds cleared stools of parasites in 23 out of 30 subjects. Drink a lot of water to help flush out your system.
Eat more fiber, which may help get rid of worms.
Probiotics (Lactobacillus acidophilus, Lactobacilus plantarum, Saccharomyces boulardii, and bifidobacteria). Help keep your digestive tract healthy. Probiotics may not be appropriate in some severely immune compromised patients. Talk to your doctor.
Digestive enzymes will help restore your intestinal tract to its normal state, which makes it inhospitable to parasites. Papain is an enzyme from the papaya plant that may help kill worms when taken 30 minutes before or after meals. Papain may increase bleeding in people with clotting disorders, or in those taking blood-thinning medications, such as warfarin (Coumadin) among others.
Vitamin C. Supports the immune system. Lower the dose if diarrhea develops.
Zinc. Supports the immune system. Zinc may interact with certain medications, particularly some antibiotics, and it may not be appropriate for people with HIV/AIDS. Talk to your doctor.
Herbs
Herbs are a way to strengthen and tone the body’s systems. As with any therapy, you should work with your doctor to diagnose your problem before starting treatment. You may use herbs as dried extracts (capsules, powders, or teas), glycerites (glycerine extracts), or tinctures (alcohol extracts). People with a history of alcoholism should not take tinctures.

Many of the herbs used to treat intestinal parasites have toxic side effects or interfere with other medications. Use them only under the supervision of a qualified practitioner. Your health care provider should treat you with the most gentle herb that is effective for the type of parasite you have. A few of the herbs that your provider might consider include:

Garlic (Allium sativum)
Barberry (Berberis vulgaris)
Goldenseal (Hydrastis canadensis)
Oregon grape (Berberis aquifolium)
Anise (Pimpinella anisum)
Wormwood ((Artemisia annua))
Curled mint (Mentha crispa)
Black walnuts (Juglans nigra)