One type of drug relies specifically on calcium carbonate and magnesium: chewable antacids. While most antacids, whether over-the-counter or prescription, contain some form of magnesium, the chewables contain both magnesium — either magnesium hydroxide or magnesium carbonate — and calcium carbonate. Some other drugs contain calcium, magnesium, or both, but the elements tend to act as fillers or buffers, not the active ingredients. For example, both calcium and magnesium help bind and bulk up certain statins, a class of anti-cholesterol drugs.
Calcium carbonate and magnesium antacids are over-the-counter drugs, considered generally safe to take without physician monitoring. They can potentially interact with some prescription drugs, however, such as anticoagulents and some antifungals, antibiotics, and tetracyclines. In some cases, calcium carbonate antacids reduce these drugs' effects; in others, they increase the risk of side effects. Anyone with kidney disease should consult a doctor before taking calcium magnesium antacids.
These antacids are considered so safe, they're recommended for pregnant women experiencing heartburn. Pregnant women are cautioned to check their antacid tablets for aspirin, which is not recommended without a doctor's advice. It is never a bad idea to check with a doctor before taking any kind of medication while pregnant, breastfeeding, or trying to conceive, however.
Both calcium carbonate and magnesium are alkaline, and they adsorb acid. Chewing a calcium carbonate and magnesium antacid can often provide swift — almost instantaneous — relief from acid heartburn. Stomach acid is necessary for digestion, however, and decreasing or eliminating it may contribute to a cycle of indigestion. It may be better in the long run for an individual to evaluate and avoid foods that cause heartburn.
An essential mineral, calcium is present in bones and teeth. If a person's diet lacks sufficient calcium, the body can leach it out of bones, leaving them weak and brittle. Calcium supplementation is a beneficial side effect of taking a calcium carbonate antacid, although calcium carbonate is not a widely recommended form for the mineral's absorption. Though it's difficult to ingest too much calcium, calcium magnesium antacids are not recommended for people with excessively high calcium levels, as indicated by a doctor's blood tests.
Calcium also works with magnesium in the body, forming an essential part of bones and helping regulate muscle tone and nerve activity. Magnesium affects the function of over 300 enzymes in the body as well. Calcium and magnesium have a complex relationship, both complementing and competing with each other.
Antacids in general can affect the body's absorption of minerals. Calcium-containing antacids in particular may interfere with the absorption of iron, zinc, manganese, and chromium. These antacids should be taken separately from supplements to help decrease the chances of interference.