Avoid taking other medications at the same time you take an antacid. Some antacids can make it harder for your body to absorb certain drugs, making them less effective. Take your other medications at least 2 hours before or 2 hours after you take calcium carbonate, magnesium hydroxide, and simethicone. Antacid, Antigas Lemon Flavor Fast relief for acid indigestion heartburn sour stomach upset stomach associated with these symptoms pressure and bloating commonly referred to as gas.