Fact is you an allergist can run these tests, virtually risk-free, and then you will know for sure. Mine said only an extremely small percentage of people they test are allergic to it. He said even if you once had a reaction, the body tends to change after a few years and there is a good chance the allergy is no longer present.
They inject a tiny bit, barely under the skin, then wait 20 minutes to see if there is any reaction, such as reddening or inflammation of the site. They also do a control that is SUPPOSED to cause a slight irritation. If the first test is negative, they do a second one with a slightly higher dose. As long as the results are negative, they increase the doses every 20 to 30 minutes for a total of five (I think).
That took from 8 a.m. till nearly noon. Back at 1 p.m. to take the first oral dose, half a pill, which is 1/4 of a normal dose. There is a one hour wait and then a 2nd dose of 1/2 strength, one pill. After one more hour and no negative reaction you get a full dose, two pills. You have to wait one for hour before leaving.
If you take a Beta Blocker, as I do, you must skip it for a day preceding the procedure, because if you have strong reaction, they use Epinephrine injection to counteract it if needed. The Beta Blocker would also block the Epinephrine.
I listened to nearly an entire recorded book on my phone while waiting! But it was well worth it.