Depends on the grade..You are suffering from hormonal changes causing Androgenetic alopecia causing hair fall. It's completely stoppable even regrowth of hair is possible with certain medications without any side effects. Treatment depends on the grade of hair loss. So, it's a must for diagnosing which grade, you are in for an effective treatment. Please  send photos of your head, by direct online consultation for accurate diagnosis and proper treatment.

Why do you want to use minoxidil in the first place . Hair fall is common and has many reasons in a young girl like your self. Get your scalp examined by a dermatologist ASAP not online as picture can be deceptive. Meanwhile try using good antioxidants and multivitamins and also get your Haemoglobin checked to rule out anaemia.

Dont use minoxidil unless the scalp is turning bald or u have pattern hair loss Consult me online

It you use Minoxidil for a pattern hair loss that is Androgenic  Alopecia or female pattern hair loss than it has to be used on a long term basis,  if you use it for Telogen Effluvium than it can be stopped once the condition  improves although  there can be a transient  hair fall on stoping Minoxidil