As much as some may not like some forms of
Niacin due to the "flush" that you can often experience, you can get a slow release version that does not produce such a side-effect. But it is quite a vasodilator and can help when used a little before you partake, perhaps an hour or so. There have been other times when I have redosed Niacin as well during an experience, and it works like a charm. But preloading seems to be the key to helping keep vasoconstriction at bay, or certainly reducing the physical manifestation of it to begin with. I often make sure that I preload
Magnesium as well, which seems to help with tension and vasoconstriction as well. In fact, Magnesium's cardiovascular/vasodilation benefits are widely recognized, and some studies reveal that Magnesium works synergistically with most classes of anti-hypertensive compounds as well.
https://pubmed.ncbi.nlm.nih.gov/22051430/
To be honest, if I could choose only one, it would be Magnesium. I have found that since employing its use, I experience little to no vasoconstriction by comparison, and it does appear to nearly negate the level of discomfort and tightness that you sure can feel sometimes which is a great thing to NOT have to think about very much if at all.
As someone else stated,
L-Arginine is also helpful in addressing such things. I have found that the Mag+ Niacin combo works really well, and it has become part of preparation for experiences and tends to make them much more comfortable. We are all different, of course, so your mileage may very. But once you can find what works for you, it can make a big difference in terms of how you feel physically. Also, others have reported the use of
Beet Root extract fairly successfully as well, and again, preloading is key. Just a few pennies worth...