Similar injection site reaction for me with QSC NAD+ unfortunately, similarly had no issues with the product from ageless(crazy expensive though). Shame since I blind bought three kits but that’s the way it goes sometimes.
In terms of preparation…Diluted to 25mg/mL with 0.9%BA bacteriostatic water and tried out a low dose of 12.5mg (0.5mL). Woke up to a warm 3” red patch at the injection site~24 hours later. I haven’t had any injection site reactions to any of the 20ish other compounds I’ve injected over the years so I don’t generally consider myself to be a strong responder when it comes to side effects. No fever/chills/etc to report though.
We’re all different of course, YMMV but just my report. First issue I’ve ever had with a QSC product, won’t order this specific product again but QSC will get more of my business in the future.