"i started taking nucynta about 4 days ago. i took 1 x 50mg tablet that morning and i felt okay. i took another one that night and i had a terrible reaction, my face got hot and my heart started beating like crazy and the beats were very irregular. i thought i was having a heart attack. luckily i am prescribed klonopin, i had to take 2 of them and it took about a half an hour to stop. i almost called an ambulance."