For immediate relief from severe acidity, you can take an over-the-counter antacid containing magnesium hydroxide or calcium carbonate, which neutralizes stomach acid quickly. For longer-lasting relief, an H2 blocker like famotidine, or a proton pump inhibitor (PPI) like omeprazole, can be taken on an empty stomach. Additionally, try to sit upright, drink some water, and avoid lying down immediately after eating. While these generic medications are highly effective for occasional relief, please consult a healthcare professional if your symptoms persist for more than a few days, or if you experience severe pain, to ensure you get the right care.