If your doctor has approved the occasional use of over-the-counter medicines for your heartburn, here is what you need to know before you go to the drugstore:

1. Antacids can have hidden side effects that could be dangerous. So read antacid labels and talk to your doctor to help you recognize products that may not be safe for you.
2. If you are on a low-salt diet, choose your antacid with care. Seltzer-type products contain a lot of salt and should not be taken by people on low-sodium diets.
3. Antacids that are high in calcium should be avoided by people with kidney problems. Calcium antacids can also cause a rebound effect, resulting in even greater acid production.
4. If your favorite heartburn remedy contains magnesium, do not take more than the recommended daily dose, and do not use it for more than a week without your doctor’s approval. Too much magnesium can cause diarrhea, and that can rush food through your colon too quickly. This “gastrointestinal hurry” keeps the colon from absorbing nutrients. With fewer nutrients to fuel your activities, you may feel tired and worn out.

Even worse, you could build up deadly levels of magnesium in your body. Magnesium is excreted from your body by your kidneys, but your kidneys have more trouble doing this as the years go by. That is why it gets easier to build up dangerous levels of magnesium as you grow older. The signs of this dangerous side effect are low blood pressure, muscle weakness, light-headedness, confusion, heart rhythm disturbances, nausea, and vomiting. If you develop these symptoms, call your doctor immediately.

Although many people think liquid antacids work better than tablet antacids, scientific evidence says otherwise. Oklahoma researchers were surprised to find that tablets actually provide greater and longer-lasting relief than liquids. A study of 65 heartburn sufferers suggested that tablets can do a better job of lowering acid levels in the esophagus and reducing the number of times stomach juices flow back into the windpipe. The tablets mix with your saliva to form a gummy substance that sticks to your esophagus better and longer than the liquid medicine. Plus, the act of chewing the tablets may bring out the natural antacids in your saliva.