I was wondering if a niacin flush was good or bad for new hairs after a FUE transplant?

1,500 grafts would not be enough to cover the area you highlited at full density. I suggest having additional consultation s to see what other doctors suggest.Often you can submit photos to top hair restoration surgeons for a complimentary evaluation. This should help lead you in the right...

This will not be a reason to not go ahead with a hair transplant. Most places will do a blood test ahead of time and this will show up but it is important that you make the doctor aware as well just so precautions can be taken. 

It is best to contact your doctor about post operative care and instructions since each doctor has a different regimen.If you have an infection you need close follow up with your doctor.