Q. Why is there recurrent pinworm infection even after two doses of Mebendazole?

Answered by
Dr. Y Siva Roja
and medically reviewed by Dr. Vinodhini. J
This is a premium question & answer published on Jan 14, 2020

Hello doctor,

I am struggling with pinworm infection. I took one dose of Mebendazole (100 mg) and it helped. Two weeks later, I took the recommended second dose and about three days after I started exhibiting symptoms again. It is now a week after taking the second dose, symptoms are not improving.

Dr. Y Siva Roja

General Medicine Internal Medicine


Welcome to icliniq.com.

I have gone through your problem. Reinfection with pinworm is quite frequent. Mebendazole two doses are the standard way of treatment. But in your case, reinfection may have occurred because of remnant eggs.

1) Please change your sheets on the bed and wash them thoroughly.

2) Thoroughly wash the undergarments as they are the major source of remnant eggs of pinworm.

3) Wash your hands properly.

4) Avoid scratching in the anal region which you may be doing because of itching.

5) If there is a school going kid at your home, please do inform the class teacher regarding this as other untreated kids may be another source.

Another major thing to consider is whether you are definitely having pinworm infection or not? In pinworm infection usually, the eggs which are laid in the perinatal region and worms are not commonly released in stools. The presence of eggs can be diagnosed with a simple tape test at your physician's office.

If this is due to any other worm infection, the required dose of Mebendazole is different and what is taken by you will not be sufficient. I suggest you get this clarified because what requires is a simple tape test and a stool examination for other ova or cysts.

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