Mebendazole Dosing for Ascaris Infection
For ascariasis (Ascaris lumbricoides), administer mebendazole 500 mg orally as a single dose. 1, 2
Primary Dosing Recommendation
The most recent UK guidelines (2025) from the Journal of Infection recommend mebendazole 500 mg as a single oral dose for treating ascariasis. 1 This single-dose regimen is equally effective as the traditional multi-day regimen and offers superior adherence. 2
Alternative FDA-Approved Regimen
The FDA-labeled dosing provides an alternative: 100 mg (1 tablet) twice daily for 3 consecutive days. 3 This regimen applies to both adults and children, with tablets that may be chewed, swallowed, or crushed and mixed with food. 3
Clinical Efficacy Data
Both regimens demonstrate excellent efficacy:
- Single 500 mg dose: Recommended by current international guidelines as first-line therapy 1
- 100 mg twice daily for 3 days: Shows >99% egg reduction rates and 86.8-100% cure rates in clinical studies 4, 5, 6, 7
Research confirms that even lower single doses (75 mg) are highly effective against Ascaris, though the 500 mg single dose represents the current guideline standard. 8
Important Clinical Considerations
- No special preparation required: Fasting or purging is unnecessary before or after treatment 3
- Retreatment protocol: If the patient is not cured three weeks after treatment, administer a second course 3
- Safety profile: Mebendazole is well-tolerated with minimal side effects; mild diarrhea occurs in approximately 22% of children 6
- Alternative option: Albendazole 400 mg single dose or ivermectin 200 μg/kg single dose are equally effective alternatives 1