Mebendazole Dosage for Ascariasis
For ascariasis, administer mebendazole 500 mg orally as a single dose, which provides excellent efficacy with minimal side effects. 1, 2
Recommended Dosing Regimen
- Single-dose therapy: 500 mg orally once is the current guideline-recommended approach for ascariasis treatment 1, 2
- This single 500 mg dose achieves cure rates exceeding 95% and egg reduction rates over 98% 3
- The tablet may be chewed, swallowed whole, or crushed and mixed with food 4
- No special preparation such as fasting or purging is required 4
Alternative Dosing Options
While the single 500 mg dose is preferred, the FDA label also describes an alternative multi-day regimen:
- 100 mg twice daily for 3 consecutive days (morning and evening) 4
- This regimen was historically used and achieves similar efficacy with cure rates of 86.8% and egg reduction rates exceeding 99% 5, 6
- The multi-day approach may be considered if the single-dose formulation is unavailable 4
Pediatric Considerations
- The same 500 mg single-dose regimen applies to both children and adults 1, 2
- Historical studies used lower doses in children (50 mg twice daily for 3 days), but current guidelines do not differentiate dosing by age for the single-dose approach 5
Treatment Failure Management
- If the patient is not cured three weeks after treatment, administer a second course 4
- Repeat stool examination 2-3 weeks post-treatment if symptoms persist 7
- Consider alternative diagnoses or resistant infection if multiple treatment courses fail 7
Important Clinical Caveats
- Mebendazole is highly effective specifically for ascariasis but should not be used for strongyloidiasis, where ivermectin 200 μg/kg is strongly preferred 2
- The drug is well-tolerated with minimal side effects, primarily mild and transient gastrointestinal symptoms 5, 8, 3
- For mixed helminth infections including ascariasis, the single 500 mg dose remains effective 1