5-HTP is a serotonin precursor that has limited application for 'replenishing serotonin', although to be able to replenish it, you certainly need to have the ingredients readily available in your body. But it won't magically all turn into serotonin, there is a limit to that. So it's just supportive / supplemental. It should be used with care and taken with a grain of salt, and is not helpful for psychotic episodes.
Stimulant psychosis is from dopamine receptor agonism mostly, but worsened by not getting enough sleep. If necessary this can be helped by taking an antipsychotic such as olanzapine (you can start with low dose), as most of those block such dopamine receptors. Things like benzos would also possibly be helpful but you would definitely need to look out not to take a lot and becoming amnestic (blacking out) and disinhibited (unrestrained behavior)... that would be a bad mix to have with the psychosis.
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