i was the same for a while, I didnt realise at the time but all my suicidal thoughts started when I started taking the SNRI antidepressant Remeron. I would fantasise about commiting suicide down to exact details.
I had it all planned out, I was going to do it by a drug overdose. Started stockpiling barbituates, benzos, GHB, etc ready for when I would do it. I never mentioned these thoughts to anyone and didnt even realise that they were abnormal until I stopped taking antidepressants. Literally the day I stopped taking these meds I never had one more thought along these lines.
Looking back it really scares me how close I was to carrying it through, and made me realise how dangerous psych meds like remeron were for me personally.
I dont think its neccesarily unhealthy to "consider" commiting suicide occasionally. I mean everyone has all sorts of irrational and bizarre thoughts/fantasies that come through their heads. It's only becomes a problem IMO when they start to consume you and you actually start taking steps to go through with it, thats when you should seek help from a proffesional I think.