16 year old boy is growing bald. What can be done? Should I consult a doctor? At 16 are medicines like Rogain safe? (Photo)

I am the mother of a 16 years old boy. His father is bald. In the past one year the hair on my son's head has become significantly and noticeably sparse. I have read that he treated at the earliest and once the hair vanishes nothing can be done .I am aware that is in his genes and eventually he might have to go for drastic measures. Should I consult a doctor ? At 16 are medicines like rogain safe? I believe it is a life long term process and when stopped could lead to loss of newly gained hairs.