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Praziquantel Side Effects

For the Consumer

Applies to praziquantel: oral tablet

As well as its needed effects, praziquantel may cause unwanted side effects that require medical attention.

Major Side Effects

If any of the following side effects occur while taking praziquantel, check with your doctor immediately:

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

Minor Side Effects

Some praziquantel side effects may not need any medical attention. As your body gets used to the medicine these side effects may disappear. Your health care professional may be able to help you prevent or reduce these side effects, but do check with them if any of the following side effects continue, or if you are concerned about them:

More common:
  • Drowsiness
  • increased sweating
  • general feeling of discomfort or illness
  • nausea or vomiting
Less common:
  • Skin rash, hives, or itching
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. Cerner Multum, Inc. "Australian Product Information." O 0

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

4. 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

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

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

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

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

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

It is possible that some side effects of praziquantel may not have been reported. These can be reported to the FDA here. Always consult a healthcare professional for medical advice.

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. This information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate safety, effectiveness, or appropriateness for any given patient. does not assume any responsibility for any aspect of healthcare administered with the aid of materials provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the substances you are taking, check with your doctor, nurse, or pharmacist.