Inderal makes me sick to my stomach but I was just wondering if I can take it on occasion?

my cardio prescribed it for palpitaions. i ahve no heart disorder and yes he told me to take it as needed for palps. it works in 10 seconds. i have taken maybe 5 in the past 3 months. it's not usually pescribed on an as needed baisis but my cardio assured me it is fine.