Bullet Grazing Head Question

Hey, everyone! This is a major question that I cannot get a good answer on Google, and no neurologist I've contacted is willing to talk to me about this.

So in my novel, which is about terrorism, the main character's cousin teaches him to fire a gun in a forest, but while they're there, a terrorist arrives and shoots at them. They survive and jump into a lake to hide (the cousin shoots the attacker to death), but the main character suffers a bullet graze across the side of his head (ideally alongside the parietal ridge). I wanted to know if there were any immediate and long-term effects to this, such as temporary blindness, vertigo, ear ringing, etc. I intend for him to survive long enough to arrive at a hospital for stitches. It doesn't penetrate his brain, but I want him to have at least one scar on his body as a reminder of what he's survived through.

Thank you so much for this!

Heyo! Thanks!

I think what the problem is that I don't know what he would be going through. I'd like for him to have a scar somewhere on his body, but if I did the head, I wanted him to be able to function without many life changes. I guess I don't know the different impacts you can have depending on what part of the head was affected. My main problem is knowing what will happen to him immediately and any other results that might impact the rest of him.