Can you use Derma Roller and PRP after SMP?

It is best to ask your doctor who will be performing your SMP, PRP, etc about your concerns. Each doctor will have their own opinion which may differ slightly and it will likely leave you more confused.Many doctors think PRP does not work.

SMP is a mid and lower dermal tattoo. I would avoid dermarolling any PRP connected with micro-needling.  These procedures can produce inflammation which has the potential to affect the SMP.  Subdermal Depo injection of PRP would be acceptable. Good luck.
Jeff Rapaport MD FAAD
Realself All-star

PRP treatments are ok after SMP, I would wait 2 weeks however, just to give enough time for the pigment to settle in and for your scalp to fully rest. 
I would avoid the dermapen, It may cause inflammation to the scalp and affect your SMP results. 

Yes, you can do whatever you want once the Scalp Micropigmentation is set up (3 days after the last session of SMP). That includes dermaroller and/or PRP