Treatment of Ascariasis
For ascariasis (Ascaris lumbricoides infection), treat with a single oral dose of albendazole 400 mg, mebendazole 500 mg, or ivermectin 200 μg/kg—all three options are equally effective with cure rates exceeding 95%. 1
First-Line Treatment Options
Any of the following single-dose regimens is appropriate 1:
- Albendazole 400 mg orally once 1, 2
- Mebendazole 500 mg orally once 1, 2
- Ivermectin 200 μg/kg orally once 1, 2
All three medications demonstrate comparable efficacy with no clinically meaningful differences in parasitological cure rates (approximately 93-98%) or egg reduction rates (96-100%) when measured 14-60 days post-treatment 3. High-quality evidence confirms that single-dose albendazole performs equivalently to single-dose mebendazole 3, and moderate-quality evidence shows no difference between albendazole and ivermectin 3.
Alternative FDA-Approved Dosing
The FDA label for mebendazole provides an alternative multi-day regimen 4:
- Mebendazole 100 mg twice daily for 3 consecutive days 4
This achieves a 98% cure rate and 99% egg reduction rate for ascariasis 4. However, the single 500 mg dose is more practical for mass treatment programs and equally effective 1.
Pediatric Considerations
The same dosing applies to both children and adults 1, 2. Tablets may be chewed, swallowed whole, or crushed and mixed with food to facilitate administration in young children 4.
Treatment Failure Management
If parasitological cure is not achieved three weeks after initial treatment, administer a second course using the same regimen 4. Across clinical trials, failure rates after single-dose therapy ranged from 0-30.3% for albendazole, 0-22.2% for mebendazole, and 0-21.6% for ivermectin 3.
Special Clinical Scenarios
Loeffler's Syndrome (Pulmonary Phase)
During larval migration through the lungs, patients may develop fever, dry cough, wheezing, and urticarial rash 1, 2. Treat with standard anthelmintic therapy (albendazole 400 mg or mebendazole 500 mg single dose) 1. Consider repeating treatment one month after resolution of pulmonary symptoms 5.
Intestinal or Biliary Obstruction
These mechanical complications (intestinal obstruction more common in children, biliary obstruction in adults) may require surgical intervention in addition to anthelmintic therapy 1, 2. Administer anthelmintics after addressing the acute obstruction.
Pregnancy
While not explicitly addressed in the guidelines reviewed, pregnant women warrant special consideration given the teratogenic potential of benzimidazoles 6. Consult obstetric and infectious disease specialists for guidance in this population.
Important Safety Considerations
No special preparation is required—fasting, purging, or bowel preparation is unnecessary before treatment 4.
Adverse events are generally mild and self-limited across all three medications, including nausea, vomiting, abdominal pain, diarrhea, headache, and fever 3. Serious adverse events were not reported in clinical trials 3.
Albendazole-specific warnings include potential for bone marrow suppression, hepatotoxicity, and embryo-fetal toxicity 6. However, these concerns primarily apply to prolonged courses used for tissue helminth infections (hydatid disease, neurocysticercosis), not single-dose treatment for intestinal ascariasis 6.
Diagnostic Confirmation
Diagnosis should be confirmed by concentrated stool microscopy (first-line) or fecal PCR (higher sensitivity when available) before treatment 1, 2. Direct visualization of adult worms (earthworm-sized, pink or white) passed in stool or occasionally regurgitated is also diagnostic 1.
Common Pitfalls to Avoid
- Do not use multiple doses when single-dose therapy is equally effective 3—this increases cost and reduces compliance without improving outcomes
- Do not confuse ascariasis treatment with strongyloidiasis—the latter requires longer courses and different monitoring 1
- Do not delay treatment in symptomatic patients—even asymptomatic individuals warrant treatment to prevent complications from parasite migration 7