A 5-year-old with perianal pruritus that worsens at night is diagnosed with Enterobius vermicularis. What is the treatment of choice?

• A. Mebendazole (Vermox)
• B. Metronidazole (Flagyl)
• C. Clindamycin (Cleocin)
• D. Thiabendazole (Mintezol)

Answer: (A)

Pinworm infection causes itching around the anus that tends to worsen at night when female worms lay eggs. Mebendazole is the preferred treatment because it’s an effective, safety-favoring anthelmintic for Enterobius vermicularis and is given in a simple dosing schedule (often a single dose with a possible repeat after two weeks to prevent reinfection). The other drugs listed don’t target helminths—metronidazole is for protozoa and anaerobic bacteria, clindamycin is an antibiotic for bacterial skin/bone infections and anaerobes, and although thiabendazole can treat pinworms, it has more side effects and is not favored as first-line. Treating household contacts and addressing environmental contamination helps prevent reinfection.