Recently there have been discussion about POIS and hypotension ( low blood pressure). My custom pre-pack is oriented toward raising blood pressure, for example with green tea, and, for me, 5-HTP ( for some people, though, and depending on the dose, 5-HTP could also lower blood pressure, so no clear predictable effect ).
I have seen case of members who, on the contrary, develop high blood pressure during POIS acute phase, so if you want to develop a custom POIS pre-pack, this is one of the many things to consider.