Thanks for the query.
As she is having irregular periods
, by taking pills the hormonal
levels can be maintained and irregularity can be treated.
So she can complete the course as adviced by your doctor.
While taking the hormonal pills some side effects can be seen. These can be decreased to some extent by taking the pills after food and taking symptomatic therapy.
Though she is 13 years old, as she is having menstrual cycles now the hormones may not have side effects on her.
For more details you can ask me through: http://www.healthcaremagic.com/doctors/dr-sree-gouri-sr/63429