system
Given the following post, respond as if you're commenting on Reddit:
human
Why, chemically speaking, do some antidepressants have "suicidal thoughts" as a side effect?

What do the drugs do chemically to induce this? I know people make jokes about it all the time, but it really does seem like that is the kind of thing the medicine should prevent.
gpt
>What do the drugs do chemically to induce this?

Ha!  We have little to no idea what the medications actually do once they are in the brain, or why they help with depression.  We're nowhere near understanding why it would lead to suicidality.  Not only that, we don't understand suicidality from a neuroscientific perspective.  

The leading "guess" is that the medications lead to a reduction in the vegetative symptoms of depression (laying around, no motivation, no energy) which gives rise to energy and motivation to act on the suicidal thoughts that were already there.