I've had a medicine induce an anxiety attack (I guess that's what you would call it) in me once. My heart raced, my breathing increased (I was panting), my head felt light-headed, and I started to sweat. It was like nothing I'd ever felt before and came out of nowhere.
Adrenaline also gets my heart racing, but stops after a minute and then always makes my stomach feel very sick.
Hot flashes are just that - hot! But maybe someone going through menopause has a different experience.