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LiverTox: Clinical and Research Information on Drug-Induced Liver Injury [Internet]. Bethesda (MD): National Institute of Diabetes and Digestive and Kidney Diseases; 2012-.

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LiverTox: Clinical and Research Information on Drug-Induced Liver Injury [Internet].

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Last Update: July 20, 2020.



Praziquantel is an anthelmintic agent with activity against a broad spectrum of trematodes and cestodes that is used predominantly in the therapy of schistosomiasis, liver flukes, and cysticercosis. Praziquantel therapy has been reported to cause serum aminotransferase elevations during therapy, but clinically apparent liver injury after its use is rare if it occurs at all.


Praziquantel (praz" i kown' tel) is a heterocyclic prazino-isoquinoline derivative with a broad spectrum of activity against several trematodes (Fasciola, Schistosoma) and cestodes (Taenia). Praziquantel is believed to act by interference with tegument calcium transport, resulting in paralysis of the parasitic worms with subsequent loss of adherence to tissue, degradation and expulsion. Praziquantel was approved for use in the United States in 1982 for schistosomiasis and subsequently for clonorchiasis. Praziquantel is also commonly used in veterinary medicine. Praziquantel is available for human use in tablets of 600 mg generically and under the brand name Biltricide. The typical dose for treating schistosomiasis in adults is 20 mg/kg (depending upon the species) three times over one day. The dose for treating clonorchiasis is 25 mg/kg three times over one day. Side effects are common but transient, and include abdominal discomfort, nausea, vomiting, vertigo, muscle aches, drowsiness, headaches and fatigue, some of the symptoms being due to its effects on the parasites. Serious adverse events include transient clinical deterioration, cardiac arrhythmias, hypersensitivity reactions and rash.


Praziquantel therapy has been associated with elevations in serum aminotransferase levels in up to 27% of patients, but these abnormalities were self-limiting. Praziquantel has been rarely associated with clinically apparent liver injury, which generally accompanied hypersensitivity reactions such as rash and fever. In a large retrospective survey from China, 2 of 25,000 treated patients were reported to have developed jaundice after praziquantel therapy, but no specific information about the two cases was provided. There have been few studies of long term therapy with praziquantel, and most controlled trials of this agent have used one day courses without serum aminotransferase monitoring. However, millions of people have been treated with praziquantel as a part of large scale control strategies in China where schistosomiasis Japonica is endemic. The combination of praziquantel preventive therapy and snail control has resulted in marked decreases in the prevalence of infection in the population with no evidence of significant toxicity. Thus, mild acute liver injury can accompany systemic hypersensitivity reactions to praziquantel, but both the allergic reaction and the liver injury tend to be short-lived and resolve rapidly even without specific therapy.

Likelihood score: D (possible rare cause of clinically apparent liver injury usually as a part of a systemic hypersensitivity reaction).

Mechanism of Injury

Praziquantel is extensively metabolized by the liver via the cytochrome P450 system and might cause hepatic injury as a result of a toxic intermediate of its metabolism. Plasma levels of praziquantel are affected by inducers (rifampin decreases drug levels) and inhibitors of P450 activity (cimetidine, ketoconazole and erythromycin can reduce drug levels).

Outcome and Management

Praziquantel is usually well tolerated and clinically apparent liver injury due to its use is rare. There is no evidence for cross sensitivity to other anthelmintic agents.

Drug Class: Anthelmintic Agents



Praziquantel – Biltricide®


Anthelmintic Agents


Product labeling at DailyMed, National Library of Medicine, NIH


Praziquantel 55268-74-1 C19-H24-N2-O2 image 135002924 in the ncbi pubchem database


References updated: 20 July 2020

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    (Expert review of hepatotoxicity of anthelmintics written in 1999; praziquantel has been reported to cause serum aminotransferase elevations).
  • Keiser J, McCarthy J, Hotez P. Chemotherapy of helminth infections. In, Brunton LL, Hilal-Dandan R, Knollman BC, eds. Goodman & Gilman’s the pharmacological basis of therapeutics. 13th ed. New York: McGraw-Hill, 2018, pp. 1001-9.
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  • Matthaiou DK, Panos G, Adamidi ES, Falagas ME. Albendazole versus praziquantel in the treatment of neurocysticercosis: a meta-analysis of comparative trials. PLoS Negl Trop Dis. 2008;2:e194. [PMC free article: PMC2265431] [PubMed: 18335068]
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  • Yangco BG, De Lerma C, Lyman GH, Price DL. Clinical study evaluating efficacy of praziquantel in clonorchiasis. Antimicrob Agents Chemother. 1987;31:135–8. [PMC free article: PMC174677] [PubMed: 3551827]
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    (19 year old man with hepatomegaly [bilirubin 3.0 mg/dL, ALT 1220 U/L, Alk P 331 U/L] and stool tests showing S. mansoni had delayed but ultimately full resolution of liver test abnormalities after praziquantel therapy).
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    (Among 607 children with O. viverrini liver fluke infection treated with tribendimidine or praziquantel, cure rates were 97% vs 95% while adverse events rose in the days following treatment in 33% vs 70%, usual symptoms with praziquantel being headache, nausea, dizziness, fatigue and abdominal cramps; no mention of ALT elevations or hepatotoxicity).
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    (Extensive review of the pathogenesis, epidemiology, clinical course, complications and management of schistosomiasis mentions that praziquantel is the most effective and widely used therapy, is active against all Schistosoma species, but only against adult worms for which reason it does not prevent reinfection and can give rise to drug resistance; praziquantel has transient, mild adverse events most of which are attributable to worm release rather than direct effects of the drug).
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    (30 year old man developed fever and rash the day after a single dose of praziquantel with abnormal liver tests [bilirubin 1.5 mg/dL, ALT 841 U/L, Alk P 468 U/L], symptoms resolving over the next week with normal tests 16 days later).
  • Darko SN, Hanson H, Twumasi-Ankrah S, Baffour-Awuah S, Adjei-Kusi P, Yar D, Owusu-Dabo E. Three monthly doses of 60 mg/kg praziquantel for Schistosoma haematobium infection is a safe and effective treatment regimen. BMC Infect Dis. 2020;20:323. [PMC free article: PMC7204294] [PubMed: 32375658]
    (Therapy of 28 patients with S. haematobium infection with 3 monthly doses of praziquantel was highly effective and serum ALT, AST and GGT levels during the 3 months were no different than levels in 53 control subjects followed concurrently).


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