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Praziquantel Side Effects

For the Consumer

Applies to praziquantel: oral tablet

Along with its needed effects, praziquantel may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking praziquantel:

Incidence Not Known

  • Abdominal or stomach discomfort with or without nausea
  • abdominal or stomach pain
  • black, tarry stools
  • bloody diarrhea
  • chest pain or discomfort
  • chills
  • convulsions
  • cough
  • dizziness
  • fainting
  • fast, slow, or irregular heartbeat
  • fever
  • hives
  • hoarseness
  • irritation
  • itching
  • joint pain, stiffness, or swelling
  • lightheadedness, dizziness, or fainting
  • painful or difficult urination
  • rash
  • redness of the skin
  • severe abdominal or stomach pain
  • shortness of breath
  • slow or irregular heartbeat
  • sore throat
  • sores, ulcers, or white spots on the lips or in the mouth
  • sweating
  • swelling of the eyelids, face, lips, hands, or feet
  • swollen glands
  • tightness in the chest
  • troubled breathing or swallowing
  • unusual bleeding or bruising
  • unusual tiredness or weakness
  • wheezing

Some side effects of praziquantel may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More Common

  • Drowsiness
  • increased sweating
  • general feeling of discomfort or illness
  • nausea or vomiting

Less Common

Incidence Not Known

  • Difficulty with moving
  • dizziness or lightheadedness
  • feeling of constant movement of self or surroundings
  • headache
  • hives or welts
  • joint pain
  • lack or loss of strength
  • loss of appetite
  • muscle aching or cramping
  • muscle pains or stiffness
  • redness of the skin
  • sensation of spinning
  • sleepiness or unusual drowsiness
  • swollen joints
  • weight loss

For Healthcare Professionals

Applies to praziquantel: compounding powder, oral tablet


Side effects varied according to dose and duration of praziquantel therapy. Side effects depended on parasite species, extent of infestation, infection duration, and parasite location in the body. Side effects occurred earlier and were more frequent and/or serious in patients with severe infestation.

Often, it was unclear if praziquantel, an endogenous reaction to parasites dying from the drug, or symptoms of the infestation caused the reported side effects.

Side effects included malaise, headache, dizziness, abdominal discomfort (with or without nausea), rise in temperature, and urticaria; generally in order of severity. Such side effects were more frequent and/or serious in patients with heavy worm burden.

Nervous system

The inflammatory reaction produced by antigenic substances released from dying cysts frequently involved increased intracranial pressure, seizures, severe headaches, nausea, and vomiting. In areas where Taenia solium was endemic, these reactions may occur as the result of undiagnosed cysticercosis in patients being treated for other parasitic infections. The duration of the reaction differs among patients. Delayed reactions have been reported.[Ref]

Very common (10% or more): Headache, dizziness

Common (1% to 10%): Vertigo, somnolence (including drowsiness)

Very rare (less than 0.01%): Seizures

Frequency not reported: Cerebral inflammatory reaction

Postmarketing reports: Convulsion, somnolence, vertigo[Ref]


Very common (10% or more): Gastrointestinal and abdominal pains, nausea, vomiting

Common (1% to 10%): Diarrhea

Frequency not reported: Abdominal discomfort (with or without nausea), gagging

Postmarketing reports: Abdominal pain, bloody diarrhea, vomiting[Ref]

A syndrome of severe abdominal pain and bloody diarrhea was reported less often during schistosomiasis therapy.

Gagging and vomiting have been reported due to the bitter taste of the tablets.[Ref]


Very common (10% or more): Fatigue

Common (1% to 10%): Feeling unwell (asthenia, malaise), fever

Frequency not reported: Rise in temperature, transient edema

Very rare (less than 0.01%): Polyserositis

Postmarketing reports: Asthenia, fatigue[Ref]


A 13-year-old male developed Mazzotti reaction after treatment with ivermectin, praziquantel, and albendazole for presumptive schistosomiasis and strongyloidiasis. Six days after receiving standard empiric therapy, he developed epigastric pain, vomiting, and urticaria. This progressed in 4 hours and included fever, general myalgia, and edema of the face, lower extremities, and penis accompanied by urticaria of the arms, legs, and trunk. He was diagnosed with a Mazzotti reaction and treated with methylprednisolone; symptoms subsided within 12 hours.[Ref]

Very common (10% or more): Urticaria

Common (1% to 10%): Rash

Very rare (less than 0.01%): Pruritus

Frequency not reported: Mazzotti-like reaction

Postmarketing reports: Pruritus, rash[Ref]


Common (1% to 10%)/Postmarketing reports: Anorexia


Common (1% to 10%)/Postmarketing reports: Myalgia

Frequency not reported: Musculoskeletal aches and fatigue[Ref]


Frequency not reported: Mild increases in liver enzymes


Very rare (less than 0.01%): Unspecified arrhythmias

Postmarketing reports: Arrhythmia (including bradycardia, ectopic rhythms, ventricular fibrillation, atrioventricular blocks)


Postmarketing reports: Allergic reaction (generalized hypersensitivity, including polyserositis)


Postmarketing reports: Eosinophilia


1. Flisser A, Madrazo I, Plancarte A, Schantz P, Allan J, Craig P, Sarti E "Neurological symptoms in occult neurocysticercosis after single taeniacidal dose of praziquantel." Lancet 342 (1993): 748

2. Watt G, White NJ, Padre L, Ritter W, Fernando MT, Ranoa CP, Laughlin LW "Praziquantel pharmacokinetics and side effects in Schistosoma japonicum-infected patients with liver disease." J Infect Dis 157 (1988): 530-5

3. Cerner Multum, Inc. "Australian Product Information." O 0

4. "Product Information. Biltricide (praziquantel)." Bayer, West Haven, CT.

5. Homeida MM, Eltom IA, Sulaiman SM, Ali HM, Bennett JL "Tolerance of two brands of praziquantel." Lancet 2 (1989): 391

6. Leblanc R, Knowles KF, Melanson D, MacLean JD, Rouleau G, Farmer JP "Neurocysticercosis: surgical and medical management with praziquantel." Neurosurgery 18 (1986): 419-27

7. Markwalder K, Hess K, Valavanis A, Witassek F "Cerebral cysticercosis: treatment with praziquantel. Report of two cases." Am J Trop Med Hyg 33 (1984): 273-80

8. Bada JL, Trevino B, Cabezos J "Convulsive seizures after treatment with praziquantel." Br Med J (Clin Res Ed) 296 (1988): 646

9. Ciferri F "Delayed CSF reaction to praziquantel." Lancet 1 (1988): 642-3

10. McMahon JE "Praziquantel: a new schistosomicide against Schistosoma mansoni." Arzneimittelforschung 31 (1981): 592-4

11. Stelma FF, Talla I, Sow S, Kongs A, Niang M, Polman K, Deelder AM, Gryseels B "Efficacy and side effects of praziquantel in an epidemic focus of schistosoma mansoni." Am J Trop Med Hyg 53 (1995): 167-70

12. Polderman AM, Gryseels B, Gerold JL, Mpamila K, Manshande JP "Side effects of praziquantel in the treatment of Schistosoma mansoni in Maniema, Zaire." Trans R Soc Trop Med Hyg 78 (1984): 752-4

13. Watt G, Baldovino PC, Castro JT, Fernando MT, Ranoa CP "Bloody diarrhoea after praziquantel therapy." Trans R Soc Trop Med Hyg 80 (1986): 345-6

14. Shorter D, Hale K, Elliott E "Mazzotti-like Reaction After Treatment with Praziquantel for Schistosomiasis." Pediatr Infect Dis J 25 (2006): 1087-1088

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.