David Snyder, PharmD, BCPP, is a board-certified clinical pharmacist and psychopharmacology expert at McLean Hospital in Belmont, Massachusetts.

Biltricide (praziquantel) is an oral prescription medication used to treat certain types of parasitic worm infections, including schistosomiasis (also known as blood flukes), clonorchiasis (Chinese liver fluke), and opisthorchiasis (Southeast Asian liver fluke). These diseases are not found in the United States, but are common in tropical regions of Asia, Africa, and South America where there is a lack of public sanitation.

Biltricide is an anthelmintic drug that works by disintegrating the outer protective layer of parasitic worms. Depending on the species, one or two days of treatment can usually clear the infection.

Biltricide comes in tablet form. Generic versions of the drug are available.

The Food and Drug Administration (FDA) approved Biltricide to treat three types of parasitic worm infection:

Biltricide is one of two drugs used to treat schistosomiasis and is considered the preferred option, as it can treat all types of schistosome. It can be used on its own or in combination with antimalarial drugs like Lariam (mefloquine) that also have antiparasitic properties.

Similarly, Biltricide is one of two drugs used for the treatment of clonorchiasis and opisthorchiasis. It is also considered the preferred treatment option.

The FDA approved Biltricide for use in people aged 1 year and older.

Biltricide is supplied as a 600 milligram (mg) oral tablet. The tablets have three scores, or notches, on them, which can be broken into four segments of 150 mg doses each. When split into its segments, the dosage of the medication can be adjusted to the patient’s bodyweight.

You will likely take the equally divided doses over one or two days, depending on the parasite type:

Take the tablet with water during meals, and make sure to swallow it whole. When broken, the tablet has a very bitter taste. Do not suck, crush, or chew the tablet, as this can make the taste worse and cause gagging or vomiting. You may crush or disintegrate and mix the tablets with semi-solid food or liquid to prevent choking in children. However, crushed or disintegrated tablets must be used within one hour of mixing.

Biltricide tablets can be safely stored at temperatures under 86 F. Keep the medication well out of reach of children and pets. Discard any tablets that have expired.

Healthcare providers sometimes prescribe Biltricide off-label for other types of parasitic worm infections. Although not approved by the FDA for these specific purposes, Biltricide’s antiparasitic properties make it beneficial in treating these infections.

Biltricide is sometimes used off-label to treat:

Most cases of schistosomiasis can be resolved with a one-day course of treatment. Clonorchiasis and opisthorchiasis (liver fluke infection) require two days. Some severe infections may require a second round of treatment, typically two to four weeks later, to fully clear the infection.

This is not a complete list of side effects; others may occur. A medical professional can advise you on side effects. If you experience other effects, contact your pharmacist or a medical professional. You may report side effects to the FDA at www.fda.gov/medwatch or 1-800-FDA-1088.

As with all drugs, Biltricide may cause side effects. Most are relatively mild and quickly resolve once the treatment is completed.

Common side effects of Biltricide include (by relative order of severity):

Uncommon side effects include fatigue, insomnia, daytime sleepiness, diarrhea, itching, dizziness, and vomiting. The risk of side effects tends to increase with the severity of the worm infestation.

Biltricide has been linked on rare occasions to potentially serious side effects, including:

It is important to call your healthcare provider if you experience any unusual, persistent, or worsening side effects.

There is also a risk of a severe allergic reaction. To date, such reactions are considered rare, and only a handful of cases of anaphylaxis have been reported worldwide. Even so, these reactions have been known to occur and can be life-threatening if left untreated.

Contact your healthcare provider right away if you have serious side effects after using Biltricide. Call 911 if your symptoms feel life-threatening or if you think you’re having a medical emergency. These include symptoms of anaphylaxis, such as:

If not treated immediately, anaphylaxis can lead to shock, coma, suffocation, heart or lung failure, and even death.

Biltricide may cause other side effects. Call your healthcare provider if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your provider may send a report to the Food and Drug Administration's (FDA) MedWatch Adverse Event Reporting Program or by phone (800-332-1088).

The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

No well-controlled human studies are available for the use of Biltricide during pregnancy, but animal studies have shown evidence of fetal harm. Speak with your healthcare provider to fully weigh the benefits and risks of treatment if you are pregnant.

If you are nursing, it is important to stop breastfeeding on the day of treatment and for 72 hours after completing therapy. Low amounts of Biltricide can pass into breast milk, although it is unclear if this poses any harm to a baby.

People with liver impairment should be monitored for adverse reactions if they are taking the recommended dose.

If you miss a dose of Biltricide, take it as soon as you remember. If it is near the time of your next dose, skip the missed dose and continue as recommended. Do not double up doses.

Try your best not to miss a dose, as doing so may reduce your chances of fully clearing the parasite. Repeat treatment may be needed if the infection is not cleared.

There is little known about the risk of Biltricide overdose.

It may be presumed that higher-than-recommended doses may increase the risk of side effects, but this has not been established. It is important to call your healthcare provider if you take more Biltricide than recommended just to be on the safe side.

If you think you or someone else may have overdosed on Biltricide, call a healthcare provider or the Poison Control Center (800-222-1222).

If someone collapses or isn't breathing after taking Biltricide, call 911 immediately.

It is important that your doctor check your or your child's progress after treatment. This is to make sure that the infection is cleared up completely and to check for unwanted effects.

If your or your child's symptoms do not improve, or if they become worse, check with your doctor.

Do not take rifampin (Rifadin®, Rimactane®) while you or your child are using this medicine. Using these medicines together may cause serious problems. However, if treatment with praziquantel is needed, stop taking rifampin 4 weeks before using this medicine. You may restart taking rifampin one day after your last dose of this medicine.

This medicine kills the worms and could cause unwanted effects (eg, serum sickness, paradoxical reaction) as your body heals, especially during the early stages of schistosomiasis. Talk to your doctor if you have concerns.

This medicine may cause heart rhythm problems. Tell your doctor right away if you or your child gets dizzy or lightheaded, have a fast or irregular heart beat, or feel like fainting.

This medicine may cause some people to become dizzy, drowsy, or less alert than they are normally. Do not drive or do anything else that could be dangerous during treatment with this medicine and for 24 hours after your last dose.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.

Do not use Biltricide if you have had a previous hypersensitive reaction to praziquantel or any other ingredient in the medication, or if you are using rifampin-based tuberculosis treatment.

Rifampin can dramatically reduce the concentration of praziquantel in the blood and make the drug less effective. If you are on rifampin therapy, you would need to find an alternative to Biltricide (see “What Medications Are Similar?”). If alternatives cannot be found, you might need to stop taking rifampin for four weeks before starting Biltricide.

Biltricide is broken down in the body by a liver enzyme known as cytochrome P450 (CYP450). Many other drugs rely on CYP450 for metabolization, and taking these drugs with Biltricide can lead to competition for available enzymes.

In some cases, the competition can dramatically decrease the concentration of praziquantel in the blood and make it less effective. Studies have shown the rifampin can, for example, reduce the concentration of praziquantel to undetectable levels in some people.

Drugs that are strong CYP450 inducers should not be used with Biltricide. These include:

Other moderate or major CYP450 inducers may require a dosage adjustment if used alongside Biltricide. To avoid interactions, always tell your healthcare provider about any drugs you take whether they are prescription, over-the-counter, nutritional, herbal, or recreational.

Other drugs can also be used in the treatment of schistosomiasis, clonorchiasis, and opisthorchiasis. They are often considered alternatives to Biltricide and typically used if you are allergic to praziquantel.

The main alternatives to Biltricide are:

However, neither Vansil or Albenza are widely available in the United States.

Each of the drugs has its shortcomings. Vansil is not only more expensive than Biltricide, but is less effective in treating certain Schistosoma species . Albenza is just as effective as Biltricide, but requires a seven-day course of treatment compared with two for Biltricide.

Biltricide (praziquantel) is an oral drug used to treat certain parasitic worm infections, including schistosomiasis and the flatworm species Clonorchis sinensis (Chinese liver fluke) and Opisthorchis viverrini (Southeast Asian liver flukes). It is often used off-label to treat other parasitic worms, including tapeworms.

Biltricide works by disintegrating the outer protective tissues of the worm, causing paralysis and death. As the parasites are dislodged from host tissues, they are largely destroyed by immune cells called phagocytes.

Schistosomiasis is a tropical disease caused by a parasitic worm called a schistosome. Infection occurs when the larva of the worm penetrates the skin of a human host. The larvae thrive in freshwater bodies, like rivers and lakes, that are contaminated with stool and urine. Children are at greatest risk, as they are more likely to play in water.

Not exactly. People with schistosomiasis indirectly transmit infection via eggs in their stool and urine. After the eggs enter freshwater, they require an intermediate host—known as the Bulinus snail—to develop into larvae. Each snail can release thousands of microscopic larvae that can infect humans.

It is not common. The disease is rarely seen in the United States unless it is in someone who has traveled to a part of the world where schistosomiasis is endemic. There are no snail species in North America that can serve as intermediate hosts for the parasite.

Tropical diseases like schistosomiasis, clonorchiasis, and opisthorchiasis are not commonly seen in the United States. However, travelers who do not follow safety precautions when traveling in endemic regions are at risk.

If you are diagnosed with schistosomiasis, seek immediate treatment to clear the infection. During treatment, supportive care can help manage symptoms of the disease, including fever and diarrhea. For uncomplicated cases, a follow-up appointment is recommended four to six weeks after treatment to confirm that you are cured of the infection (based on stool and/or urine tests).

If traveling to an endemic area, you can prevent flatworm and tapeworm infections by:

There are currently no vaccines for schistosomiasis, clonorchiasis, or opisthorchiasis.

Verywell Health's drug information is meant for education purposes only and not intended as a replacement for medical advice, diagnosis, or treatment from a healthcare professional. Consult your doctor before taking any new medication(s). IBM Watson Micromedex provides some of the drug content, as indicated on the page.

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