Vasoconstriction killing gains?

I have been prescribed ADHD medication. Due to its affects on the central nervous system, the medication can act as a vasoconstrictor. This of course means less blood flow to my penis whilst on the medication.

Will this mean I can’t gain as much due to slower healing? Is it actually blood flow that causes the repair and increase in size or something else? Not sure if I am misunderstanding how PE actually works.