What are the long term health risks of antidepressants?

I am on mirtazapine 30mg and worry often about the risks to my health, theyre not mentioned, people only ever talk about the benefits of them and not the risks, for example, Ive been on a few different ones now and have known many people who have taken them and it seems that the bad effects, failings and health risks far out way the benefits that the doctors feed patients. I was particularly wondering about the long term health risks to me and if taking them could decrease a persons life expectancy?