question: Upon taking a pre-workout supplement that had 1,3 Dimethyl in it, I have had what feels like tightness, heaviness, and what I call full in my chest; this was a supplement that was taken 48 hrs ago. I had taken something similar in March; had the same problem and then went to the cardiologist, had a stress echo, and ecg, and etc. Everything looked fine but: it took 2 weeks to return to normal. So why did I try something 48 hrs ago? I didn t know it had 1,3 Dimethyl in it. It almost appears as if I have some costochondritis, aortitis or some sort of inflamation upon taking this product. Yes, I will not ever try/take another supplement period: but what is your knee-jerk reaction ? My heart rate does not fluctuate by the way. No tachycardia.