Can Rogaine harm healthy hair?

Rogaine does not harm hair.  It does not harm healthy hair.  If you are afraid of using Rogaine, you should discuss your concerns with your doctor.  You should have an exam before starting any treatment.

In theory it should not harm healthy hair. However, hairs that may look healthy but really be in the process of androgenetic fall out may show expediated loss. 

Yes, there is no negative effect for minoxidil (Rogaine) for normal hair but it can cause skin irritation and impact blood pressure as a side effect. Be sure to read the insert your you buy it. Some people do report shedding for up\ to 3 months after starting this medication, but it most likely will not be the normal hairs that shed but the miniaturized hairs that are impacted by the genetic balding process. This shed will reverse if it should happen.

Rogaine is one of the FDA approved medications in the united states.  It is used mainly to reduce or prevent future hair loss of your native hair.  Usually after hair transplant, you would get regrowth from the transplanted hair, however your native hair are still prone to be lost.  Therefore, if stop using Rogaine, the chances are you will lose your native hair at a rapid pace.  Therefore, to keep the native hair we usually recommend to start using Rogaine after a couple weeks and return to your regular medical regiment.  If you do not want to do it, then you may need additional surgery in the new future.