Andrew Fryer said

Fiddlerman said
visit your doctor and tell him or her what you will be doing and they will prescribe beta blockers for you. They are harmless and you need so little to actually avoid getting nervous in the slightest. As long as you are only doing it once in a while, you're good.
Inderal used to be common and doses of around 10 - 20mg will suffice for this.  

Beta-blockers are not absolutely harmless. If you use them occasionally under medical advice and prescription, they shouldn't cause harm, but if you take them long-term, you need regular blood tests to make sure they are not harming your kidneys.

I began on 2.5mg of Bisoprolol daily and was eased up to the maximum of 10 mg daily during the course of more than 2 years with quarterly blood tests on the way. But going up from 7.5 to 10 sent my pulse down to 40 per minute, which is causing my doctor worries, but I don't notice any side-effects.  

I meant if used once in a while, not regularly. Also, I am not a doctor.... Take my advice with a grain of salt. The few times that I took them, they didn't affect my heart rate at all. Only the ability for my heart to race.