Last night was the first time I took my nitrogylcerin. Since today is Sat., I will wait until Mon. to call my dr. After I felt the severe pressure I had described, I took the pill as prescribed. After 15 min., I felt a warm then hot sensation in my back and chest. It spread to my left upper arm and down the arm. It was very soothing. Was this my imagination or the med? Does this indicate possible blockage? I did not have any other side effects.