Praziquantel

Key facts

• Praziquantel is an antiparasitic (anthelmintic) that treats infections caused by both tapeworms (cestodes) and flukes (trematodes), including schistosomiasis.
• It's usually taken as a single dose or a short course with food, and the tablets taste very bitter, so swallow them quickly with liquid rather than chewing them.
• When used for a brain tapeworm infection (neurocysticercosis), the dying parasites can trigger seizures or swelling in the brain, so it's typically given together with a corticosteroid and sometimes an anti-seizure medicine, under close medical supervision.
• Seek urgent care for a new seizure, severe headache, or vision changes during or after treatment.

What praziquantel treats

Praziquantel treats tapeworm infections (cestodes), including pork tapeworm and its tissue form, cysticercosis, and fluke infections (trematodes) affecting the liver, lungs or intestines. It also treats schistosomiasis, a disease caused by blood flukes acquired through contact with contaminated fresh water. It does not treat roundworm infections or hydatid disease (echinococcosis), which need different drugs.

How praziquantel works

Praziquantel increases calcium flow into the parasite's muscle and outer surface layer. This causes the worm's muscles to contract severely and damages its surface, so it loses its grip on host tissue and the immune system can clear it.

Before you take it

• Tell your doctor if you have, or might have, cysticercosis affecting your eyes. Treating cysts there can cause them to break down and permanently damage vision, so eye involvement must be ruled out first.
• Tell your doctor about any history of seizures or possible brain cysts, since treatment can trigger a seizure as the parasites die.
• People with significant liver impairment may need a dose adjustment.
• Avoid driving or operating machinery on the day of treatment and the day after; it commonly causes dizziness and drowsiness.

Side effects

Common effects include headache, dizziness, nausea, abdominal discomfort, and fatigue, often as the parasites break down.

Seek urgent medical care for:

• A seizure, severe headache, confusion, or vision changes.
• Severe abdominal pain or persistent vomiting.
• Yellowing of the skin or eyes.
• Signs of an allergic reaction: rash, swelling, difficulty breathing.

Safety essentials

• If there's any chance of brain or eye cysticercosis, this needs to be assessed before treatment, since killing parasites in these tissues can cause seizures, swelling, or vision loss. Corticosteroids and monitoring are often used alongside praziquantel for neurocysticercosis.
• Take tablets with food and swallow them whole with liquid. The bitter taste can trigger gagging or vomiting if chewed.
• Avoid driving or tasks needing full alertness on the day of and the day after treatment, since dizziness and drowsiness are common.

This page is educational and does not replace advice from a doctor or pharmacist who knows your health history.