What an acute reaction actually looks like, and why "I've used this before" doesn't protect you *PSA: The dog GIF is actually funny because I was literally home alone with my 2 dogs.. who would not have properly executed CPR 🙄* I want to write this one up properly, because I had an experience this week that I've spent years telling other people to watch for, and it still caught me off guard when it happened to me. If you inject anything, peptides or otherwise, this is worth ten minutes of your time. WHAT HAPPENED 25mg of NAD+, subcutaneous. That is a low dose by any standard. I pushed it fast, which I now think was a contributing factor but not the whole story. Seven to ten minutes later, in this order: my mouth started watering in that specific way that comes right before you get sick, and I went clammy. Then nausea, indigestion, and hiccups. Then abdominal cramping that was, by a wide margin, the worst part of the whole thing. Somewhere in there my ears started itching. The detail that made me take it seriously was that it came in waves. Not one peak that built and faded, which is what a flush reaction does. It would ease off, then roll back in, minutes apart. That cycling means mediator release is still active rather than resolving, and it is a very different animal from a niacin-style flush. I took nothing for it. It settled on its own over a couple of hours, and I thought I was through it. Then hives appeared after I had already improved. That is a biphasic reaction, and it is the single most important thing in this entire post, so I am going to come back to it. The hives have since resolved. I gathered my thoughts for this post sitting at Labcorp getting an acute tryptase level drawn, with an order for a baseline draw on a symptom-free day, and I have a prescription for epinephrine in hand. I do not have answers yet. I have a plan, which is more than I had this morning. WHAT IS ACTUALLY HAPPENING IN AN ACUTE REACTION Mast cells are immune cells that live in the tissues where your body meets the outside world. Skin, gut lining, and airways are packed densely around blood vessels and nerves. What makes them different from most immune cells is that they are preloaded. They hold granules full of ready-made inflammatory mediators, so when they fire, there is no synthesis delay. It is not a response being built. It is a warehouse being emptied.