Antacids can help with gas, but it’s not a symptom addressed by all OTC antacids. Proton pump inhibitors don’t specifically target gas and bloating, but antacids containing simethicone, bismuth subsalicylate, or magnesium can relieve gas symptoms in addition to reflux and indigestion. “Some antacids may contain magnesium, which will have a laxative effect at certain dosages,” Dr. Birnstein says.