How long do hair loss treatments like scalp tattoos or injections last?

Recently, the hair around the crown of my head has been rapidly thinning and becoming less dense. I considered taking hair loss medication, but due to concerns about secondary side effects, I am currently looking into receiving direct procedures such as scalp injections or scalp micropigmentation (SMP) for now.

The most 궁금한 (curious) part before starting treatment is retention.

I am curious about how long the effects of these hair loss treatments usually last on average.

I wonder if it’s not a matter of just one or two procedures, but something I have to visit the hospital regularly for the rest of my life.

Alternatively, I would like to know if receiving it more than a certain number of times allows me to live comfortably for a few years without worrying about it.

Since it is not a cheap or time-consuming process, I think I can only start once I am confident about the tangible effects I can experience after a single treatment and the duration of the hair loss treatment results.

I would be very grateful if you could provide an honest response regarding the results of procedures related to the crown or hairline.