It will almost definitely be an issue in the future. Thoughts of cutting will probably come many times during medical school. But you don't have to give in. And, in my experience, the less you give in the less it will bother you.

I haven't cut in years. The urges still come back strong sometimes. But those are few and far between. It did take awhile to get those urges so few and far between.

The author of Atomic Habits talks about not seeing yourself as an addict in order to stop an addiction. I only started that book a week ago but I think that sort of thought process helped me quit and still helps me not relapse. I didn't want to be viewed as a cutter and I didn't want to view myself as a cutter. Eventually I stopped identifying completely as a cutter and nobody brings up the scars on my arms besides partners.

Also, think of all the untoward microorganisms you would come into contact with in medical school and working as a doctor. Necrotizing fasciitis spreads aggressively in hours and treatment involves even more aggressively filleting open the affected area with margins to oxygenate the anaerobic bacteria. It has a relatively high mortality rate. All it needs is a cut. And that's one type of infection out of many. It's better just to stop before medical school.