Treatment of Pinworm Infection
The recommended first-line treatment for pinworm (Enterobius vermicularis) infection is a single oral dose of either albendazole 400 mg or mebendazole 100 mg, with a mandatory repeat dose in 2 weeks to eradicate newly hatched worms. 1, 2
Medication Options and Dosing
First-Line Agents (Equal Efficacy)
Albendazole 400 mg: Single oral dose, repeated in 2 weeks 1, 2
Mebendazole 100 mg: Single oral dose, repeated in 2 weeks 1, 2, 4
Pyrantel pamoate 11 mg/kg (maximum 1 g): Single dose, repeated in 2 weeks 3
Why the 2-Week Repeat Dose is Critical
The repeat dose at 2 weeks is essential because antihelminthic drugs kill adult worms but may not eliminate all eggs already present in the environment or on the patient. 1 The 2-week interval allows any eggs that survived initial treatment to hatch and mature into adult worms, which are then killed by the second dose, breaking the cycle of autoinfection. 3
Treatment of Household Contacts
All household members should be treated simultaneously, especially when there are multiple or repeated symptomatic infections. 3, 5 This includes sexual partners in adults. 5 Reinfection is extremely common even with effective medication due to the ease of fecal-oral transmission and environmental contamination. 3, 5
Management of Recurrent Infections
For patients with persistent or recurrent infections despite standard treatment:
- Consider a prolonged "pulse scheme" treatment for up to 16 weeks 5
- Re-evaluate compliance with hygiene measures 5
- Ensure all household contacts have been treated 3, 5
- If symptoms persist after treatment, repeat the cellophane tape test 3 weeks post-treatment 4
Important caveat: Recurrences are typically due to reinfection (particularly autoinfection) rather than treatment failure, given the short life span of adult pinworms. 3
Essential Hygiene Measures (Non-Negotiable Adjuncts)
Medication alone is insufficient without strict hygiene practices:
- Frequent handwashing, especially after bowel movements and before meals 3
- Clip fingernails short 3
- Avoid finger-sucking, nail-biting, and scratching the anogenital area 3
- Daily morning bathing to remove eggs deposited overnight 5
- Change and wash underwear, bedding, and towels in hot water 5
Special Populations
- Pregnant women: Use pyrantel pamoate instead of mebendazole or albendazole 3
- Children and adults: Same dosage schedule applies to both 4
- Infants <2 years: Rarely affected; if treatment needed, expert consultation recommended 6
Diagnostic Confirmation
The "cellophane tape test" (sellotape test) is the preferred diagnostic method, performed by placing adhesive tape on the perianal skin in the morning before bathing or defecation. 2 A single test has only 50% sensitivity, but performing the test on three consecutive mornings increases sensitivity to approximately 90%. 3 Stool examination is not recommended as pinworms and eggs are not usually passed in stool. 3
Common Clinical Pitfalls
- Treating only the symptomatic patient: This guarantees reinfection from untreated household members 3, 5
- Forgetting the 2-week repeat dose: Single-dose treatment has high failure rates due to environmental egg persistence 1
- Inadequate hygiene counseling: Medication without hygiene measures leads to rapid reinfection 3, 5
- Examining stool samples: This has extremely low yield for pinworm diagnosis 3