Well there's always the risk of meds failing, but if you're going that route, I recommend getting a hold of something to prevent you from puking it all up, I almost OD'd on opium tincture one time after I had just come out of the hospital and I was really sick, more than .5ml can mess you up really good if you have no tolerance and you're a tiny person, I'm not sure how much I had as my ex was the one who got me to take it, I happened to wake up many hours later and I couldn't poop for days, I didn't seem to have any other damage, my eyes were a bit baggy but it didn't stay that way for very long.
It felt very peaceful though, I had zero nausea, sweet and peaceful almost daydream or lucid dreaming state while eased into unconsciousness, absolutely no SI, it was just immediate acceptance as the thought crossed my mind that I might pass away.
I have no experience with doing it deliberately I'm afraid. Someone should notice this post eventually though.