Hello Metallic taste is not a side effect of zantac , this is very commonly used ranitidine . These measures may be helpful for you . Try raising the head of you bed about 4 inches with blocks. It might also help to avoid eating or drinking for 2-3 hours before you lie down. To help control stomach acid one should not drink alcohol or drinks with caffeine in them or eat chocolates or pizza or burger or sweets or greasy or spicy foods. Also take some antacid but if symptoms are severe ( acid reflux ) you may need drugs like pantoprazole-d once or twice in day on empty stomach . Since this is a prescription drug so take a prescription form your doctor. 2 Some times over eating causes such acid reflux , so take care about that. 3 Tension or anxiety is the root cause of such symptoms , so be careful . Hope these measures help you. Good luck.