No, I mean nicotine as I clearly indicated in my comment. It's not harmless and its ridiculous to think a drug that constricts the vessels and blood flow in your body would be so.
Without knowing more about human physiology, this physiological description is a boogeyman. Someone could describe the physiological effects of eating lettuce while making the same claim about said effect and it would be obvious to a layperson as nonsense only because they know the topic. It’s not ridiculous to think this is possibly harmless in certain contexts.
Why? Because it increases blood pressure?
That's a problem if it's chronic and severe, afaik a milk vasoconstrictive effect isn't going to kill you.
> Maybe both aren't great for you?
Maybe? You are the one making strong assertions about vasoconstrictors. Maybe you should take this opportunity to challenge your beliefs on this by digging into scientific literature.
Also, "aren't great" is such a softening of your original opinion "just terrible". Why argue for your ignorance when there is actual scientific literature?