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Oral Anthelmintics

 
 

Preface

Anthelmintics refers to a type of medications used to treat infections caused by parasitic worms (helminths) in humans and animals. Common intestinal parasites that infect humans include roundworms, pinworms, tapeworms, hookworms and liver flukes.

 

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Oral Anthelmintics*

In Hong Kong, all registered anthelmintics for human use are administered orally and are available in formulations such as tablets and chewable tablets.

Important Notice: If you experience symptoms or suspect you have a parasitic worm infection, you should consult your doctor for proper diagnosis before initiating any medications. Do not self-medicate.

Commonly used oral anthelmintics include:

  1. Mebendazole: For the treatment  of roundworm, pinworm, and hookworm infections;
  2. Flubendazole: This drug is an analogue of mebendazole and has similar actions and uses as mebendazole. It is used for the treatment of roundworm, pinworm, and hookworm infections;
  3. Praziquantel: For the treatment of tapeworm and fluke infections; and
  4. Pyrantel: For the treatment of roundworm and pinworm infections.


 

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Common Side Effects and Precautions

Anthelmintics*
 
Common side effects*
 
Precautions*
 
Mebendazole/flubendazole
  • Abdominal pain
  • Gastrointestinal discomfort
  • Diarrhoea
  • Headache
  • Dizziness
  • Patients given high doses should be supervised closely with blood counts and liver function being monitored

  • High-dose therapy may be inappropriate in patients with hepatic impairment

Praziquantel
  • Headache 
  • Diarrhoea
  • Dizziness
  • Drowsiness
  • Malaise
  • Abdominal discomfort
  • Nausea
  • Vomiting
  • Patients should be warned that praziquantel may cause dizziness or drowsiness, and if affected they should not drive or operate machinery during or for 24 hours after treatment
Pyrantel
  • Nausea and vomiting 
  • Anorexia
  • Abdominal pain
  • Diarrhoea
  • Headache
  • Should be used with caution in patients with hepatic impairment
 

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General advice

  • Strictly adhere to the dosage, timing, and administration instructions provided by your doctor or pharmacist.
  • Complete the entire prescribed course of anthelmintic medication, even if your symptoms improve or disappear early. Premature cessation may result in incomplete eradication of the parasites.
  • Some measures  to prevent  recurrent infections include:

    - Avoid scratching the perianal area (the skin around the anus).
    - Wash hands and fingernails thoroughly with soap and water frequently, particularly befor eating or preparing food, and immediately after using the toilet or handling soil.
    - Keep fingernails short and clean by trimming them regularly.
    - Wear protective footwear when working in fields, gardens, or areas with exposed soil.
    - Avoid the consumption of raw or undercooked meats and seafood, including pork, beef and fish.
    - Drink only boiled water or bottled beverages sourced from reliable sources.

 

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Communication with Your Doctor*

  • It is important to consult your doctor to determine the diagnosis and appropriate treatment option. Your doctor will prescribe the most suitable anthelmintic based on your clinical condition, medical history and response to treatment.

  • If your symptoms persist or fail to improve within a few days of initiating treatment, or worsen over time, seek medical re-evaluation promptly.

  • Inform your doctor about your current medications, including over-the-counter products or dietary supplements, as well as your medical history, as some medications may interact with your anthelmintic medication and certain medical conditions may require special precautionary measures.
  • Inform your doctor if you are pregnant, planning to become pregnant or are currently breastfeeding.
  • Seek medical advice as soon as possible if you experience any severe, unusual, or worsening symptoms or side effects suspected to be related to the medication.
 

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Storage Guidelines

Oral anthelmintics should be stored in a cool dry place. Do not refrigerate unless specified. Always keep medications out of reach and sight of children to prevent accidental ingestion.



*This information may not cover all possible side effects, precautions, or medical advice. Always consult your healthcare professional for guidance.

 

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Acknowledgement: The Drug Office would like to thank the Professional Development and Quality Assurance Service (PD&QA) for their valuable contribution to the preparation of this article.
 



Drug Office
Department of Health
June 2026

 

 

 

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