Pinworms are the generally cause of perianal itching. The itching is usually worse at night. The itching is caused by deposition of eggs around the perianal area which causes local irritation and inflammation. Scratching without washing of the hands leads to auto-ingestion of the eggs and continuation of the pinworm s lifecycle. I would recommend: -frequent hand washing, especially after bowel movements -clipping and maintain short finger nails -washing anus and genitals daily in the shower -avoid scratching of anus -avoid putting fingers near nose or mouth -getting another dose of zentel. Repeat treatment after 2 weeks is often recommended. -All symptomatic family members should be treated. -wash clothing and bedding to help prevent reinfection -avoids bathing, showering is preferred -do not share washcloths Treatment is usually mebendazole or albendazole, single dose, which generally needs to be repeated 2 weeks after first dose due to the high frequency of reinfection.Refractory cases may (rarely) require retreatment every 2 weeks for 4 to 6 cycles.