Heartburn during pregnancy can really be a killer, but I would always advise trying something non-medical first. It's especially important during the first trimester; baby is not quite as vulnerable after that time.
Not eating giant meals (especially at night) but eating often, chewing gum after each meal (saliva is supposed to help with stomach acid somehow), and sleeping with my head elevated were the keys for me.
That said, I don't want anyone to suffer. If lifestyle modifications aren't doing the trick, well, talk to your doctor and do what you need to do! Zantac is just one of several heartburn medicines that are category B that you can try.