Self-harm is included in the first precept of “No Killing.” Harming or taking our own life would be violating the first precept. Below is a comment that I saved a few years back from a Reddit post that I still reflect on to this day.
“In Buddhism we take a stance of non-violence and non-harming to all sentient beings, including ourselves.If you would not hurt another person because you care for them, because you are compassionate to them, because you love them, then why would you hurt yourself?
When we care for ourselves, when we are compassionate to ourselves, when we love ourselves, then we engender a genuine concern for our own health and happiness, mentally and physically.When I negative talk and tell myself “You can’t achieve great things. You are so lazy. Why are you so terrible.” This is not kind. I would never say this to someone else I care about, so why would I say it to myself?
When we do things to the body, like drink a lot, our body becomes sick, and has to try to get rid of all that and restore health. When we eat a lot of fatty foods we have diseases of the body which happen. So we have to really be kind and compassionate to our body too, and really take it’s health and happiness into consideration.
Be kind to yourself, be loving to yourself, be compassionate with yourself, be harmonious and non-violent with yourself. When we are truly compassionate to ourselves, out of wisdom, we do not do things to harm ourselves. Once the Buddha was ascetic, he starved himself to the point of near death, but when he realized this was not the route to ending suffering, that’s when he ate rice and sustained himself.
Buddhists take the middle way. Neither extreme luxury, nor extreme deprivation. Responding to the necessities of ourselves and fulfilling them, as appropriate, without harming ourselves or others.“
Smile and be well!