An anti-worm (anthelmintic) medicine
Praziquantel
An anti-worm medicine used especially for schistosomiasis and tapeworm infections.
What is Praziquantel?
Praziquantel is an anti-worm (anthelmintic) medicine used especially to treat schistosomiasis, also called bilharzia, a water-borne infection caught in some tropical and subtropical regions, as well as tapeworm and certain fluke infections. It works by paralysing the worms and damaging their outer layer so the body can clear them. It is usually a short course taken with food, and is often very effective. It is generally well tolerated, with mild dizziness, headache and stomach upset being the main effects, and is used carefully in certain brain infections under specialist care.
Education and reference only. This is a plain-language guide to Praziquantel — it deliberately contains no doses. Doses depend on the person, the brand and the reason for treatment, and belong with your prescriber. Always check the BNF, the product labelling (SmPC) and follow medical advice.
What it is
Praziquantel, sold as Biltricide, is an anti-worm medicine used mainly for flatworm infections. Its most important use is treating schistosomiasis (bilharzia), an infection caught by contact with fresh water in parts of Africa, Asia and South America. It is also used for tapeworm infections and some other flukes. It is taken by mouth as a tablet, usually as a short course, often as a single day's treatment, and is generally given under guidance because diagnosis and follow-up matter. It is taken with food.
How it works
Praziquantel makes the worm's muscles contract and paralyses it, while also damaging its protective outer skin (the tegument). This combination leaves the worm unable to hold on and exposes it to the body's defences, so it is dislodged and cleared. For schistosomiasis the medicine is most effective against the mature worms, which is one reason treatment is sometimes timed or repeated after exposure. Taking it with food helps it be absorbed and reduces stomach upset.
Company & origin
Originated / developed by: Generic (long-established).
An anti-worm medicine used in the UK especially for schistosomiasis (bilharzia) and tapeworm infections.
Practical use
How to take Praziquantel
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- Take it with food and swallow the tablets whole with water, without chewing, as they taste bitter.
- Take the short course exactly as prescribed, which for schistosomiasis is often over a single day.
- Expect that mild fever, itching or tummy upset as the worms die can be a sign it is working.
- Take care driving or doing skilled tasks until you know how the dizziness or drowsiness affects you.
- Tell your specialist about any possible brain or eye involvement, as this needs particular care.
- Mention relevant travel and freshwater contact to your team so the right follow-up is arranged.
Weighing it up
Advantages & disadvantages of Praziquantel
Advantages
- Very effective against schistosomiasis (bilharzia) and many tapeworm infections.
- Usually a short course, often given over a single day.
- Generally well tolerated, with mostly mild and short-lived side effects.
Disadvantages
- Can cause dizziness and drowsiness, which affect driving and skilled tasks.
- Symptoms as the worms die can be uncomfortable, even though they often signal it is working.
- Needs particular specialist care if there is any chance of brain or eye involvement.
Practical use
Good to know
Praziquantel is usually a short and often very effective treatment, frequently given over a single day for schistosomiasis. As the worms die they can release substances that briefly cause symptoms such as fever, itching or tummy upset, which is generally a sign the treatment is working. It is taken with food and the tablets are swallowed whole with water rather than chewed, as they taste bitter. Special care is needed if there is any chance of worm cysts in the brain or eye, because rapid die-off there can cause problems, so this is handled by specialists. Mild dizziness and drowsiness are common, so take care driving until you know how it affects you, and as with travel-related infections, mention any relevant travel and symptoms to your team.
Who should not take it / use with caution
- It is avoided where there is eye involvement by the parasite, as worm die-off there can be harmful.
- Brain involvement (neurocysticercosis) needs specialist handling rather than ordinary use.
- Anyone who has had a serious allergic reaction to praziquantel.
Monitoring
- Reviewing travel history and confirming the diagnosis before treatment.
- Watching for die-off reactions and managing them, especially with brain or eye involvement.
- Checking response and arranging follow-up tests after treatment where needed.
Side effects
- Dizziness, drowsiness, headache, nausea and tummy upset are the most common effects.
- Fever, itching or a rash as the worms die, often a sign the treatment is working.
- Rarely, more serious reactions, particularly if cysts are present in the brain or eye.
Key interactions
- Medicines that lower its levels, such as rifampicin and some anti-epileptics, can reduce its effect.
- Some medicines, such as certain steroids and cimetidine, can change its levels.
- Grapefruit juice can raise its levels, so it is best avoided around treatment.
Available as: Tablets taken by mouth.
Answers
Praziquantel: frequently asked questions
What is praziquantel used for?
It is used especially for schistosomiasis (bilharzia), a water-borne infection caught in some tropical regions, and also for tapeworm and certain fluke infections.
Why do I feel worse for a short time after taking it?
As the worms die they can release substances that briefly cause fever, itching or tummy upset; this is often a sign the treatment is working and usually settles.
How should I take the tablets?
Take them with food and swallow them whole with water without chewing, as they taste bitter; follow the short course exactly as prescribed.
Can it make me drowsy?
Yes, dizziness and drowsiness are common, so take care driving or doing skilled tasks until you know how it affects you.
Is it safe if the infection involves the brain or eye?
These situations need particular specialist care, because rapid die-off of worms in the brain or eye can cause problems, so they are not treated in the ordinary way.
Authoritative sources
- BNF
- NICE CKS
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