Talk to General Physician on Mebendazole 500 Mg

I want to ask about a medicine named "Mebendazole" as we receive a notice from my sister's school that tomorrow a team will come to give this medicine to the students ages from 5 years to 14 years. So, should we allow to give the medicine to my sister as she is 12 years old and she don't have any symptoms regarding any kind of worms as I googled it and found that this medicine is used for the treatment of worms. And they are giving 500mg, is it fine to give 500mg tablet to the children?. Also, I read that it has many side effects. So, kindly tell me if it is okay to give her the medicine or not?