Hello, I Started Taking Penicillin VK (500 Mg 2x/day For

Hello, I started taking Penicillin VK (500 mg 2x/day for 10 days) for streptococcus 3 days ago and I have been experiencing heartburn several hours after taking the medication. I do not have any allergies, nor any allergies to medication. I have also taken Penicillin VK before, but this is the first time this heartburn has happened. I'm actually taking pharmacology right now and heartburn was not one of the adverse effects we talked about with Penicillin. Is this still a normal side effect?