Treatment of Ascaris Lumbricoides (Roundworm) in Stool
A single oral dose of albendazole 400 mg is the recommended first-line treatment for a patient who has passed an Ascaris worm in their stool. 1
First-Line Treatment Options
You have three equally effective single-dose options for treating confirmed ascariasis:
- Albendazole 400 mg orally once 2, 1
- Mebendazole 500 mg orally once 2, 1
- Ivermectin 200 μg/kg orally once 2, 1
All three medications achieve approximately 93% parasitological cure rates within 14-60 days and are considered therapeutically equivalent. 3 The choice between them is primarily based on local availability and cost, as no clinically meaningful differences in efficacy or safety have been detected. 3
Alternative Mebendazole Dosing
If using the standard mebendazole formulation (100 mg tablets), the FDA-approved regimen is 100 mg twice daily for 3 consecutive days. 4 This multi-day regimen achieves similar cure rates to the single 500 mg dose. 3
Key Clinical Points
Treatment is indicated even in asymptomatic patients to prevent serious complications including intestinal obstruction (especially in children), biliary obstruction, and migration-related issues. 5
No special preparation is required - no fasting, purging, or bowel preparation is necessary before or after treatment. 4
The medication can be administered flexibly - tablets may be chewed, swallowed whole, or crushed and mixed with food. 4
When to Retreat
If the patient is not cured three weeks after initial treatment, administer a second identical course. 4 Treatment failure rates range from 0-30% depending on infection intensity and individual factors. 3
Monitoring and Follow-Up
Confirm cure by stool microscopy 3-4 weeks post-treatment if clinically indicated, though routine follow-up is not necessary for uncomplicated cases in asymptomatic patients. 1
Watch for persistent symptoms that might indicate complications requiring surgical intervention, particularly intestinal or biliary obstruction. 1
Safety Profile
All three anthelmintic options are well-tolerated. 3 The most commonly reported adverse events are mild and self-limited:
No serious adverse events have been reported in clinical trials comparing these medications for ascariasis. 3
Special Populations
Pregnant women should receive pyrantel pamoate (11 mg/kg as a single dose, maximum 1 g) rather than albendazole or mebendazole due to teratogenicity concerns. 5
Children and adults receive the same dosing - the 400 mg albendazole or 500 mg mebendazole single dose applies across all age groups. 2, 4
Clinical Pitfall to Avoid
Do not delay treatment waiting for stool microscopy confirmation if an adult worm has been visualized - direct visualization of the characteristic earthworm-sized white adult worm passed in stool is diagnostic and sufficient to initiate treatment immediately. 2