My Children Is 5yrs Boy N 3 Yrs Girl .they

My children is 5yrs boy n 3 yrs girl .they are suffering from pineworm problem i m giving 3 dosage this last sunday but still it seen pinworm in stool so pls can u give me any solution for this and my daughter is having same problem before als.and i m giving same zentel medicine.Does it danger to give again an again.