Antacids are taken to relieve heartburn or indigestion caused by excess stomach acid. There are several kinds of antacids. Learn what ingredients are in each type so that you can avoid any adverse effects.

• Sodium bicarbonate antacids (such as Alka-Seltzer and Bromo Seltzer) contain baking soda. Avoid these antacids if you have high blood pressure or are on a salt-restricted diet. Alka-Seltzer contains aspirin, which is linked to Reye syndrome, a rare but serious illness in children.
• Calcium carbonate antacids (such as Tums and Alka-Mints) are sometimes used as calcium supplements. These products may cause constipation.
• Aluminum-based antacids (such as Amphojel) are less potent and work more slowly than other products do. They may also cause constipation. Some may cause calcium loss and should not be taken by women who are past menopause. If you have kidney problems, check with your doctor before using aluminum-based antacids.
• Magnesium compounds (such as Phillips' Milk of Magnesia) may cause diarrhea.
• Aluminum-magnesium antacids are less likely to cause constipation or diarrhea than are aluminum-only or magnesium-only antacids. Examples include Maalox, Mylanta, and Riopan. Many of these types of antacids contain simethicone to help break down gas bubbles in your stomach.
• Antacids with alginic acid (such as Gaviscon) contain a foaming agent that floats on top of the stomach contents. This may help keep stomach juices from coming in contact with your esophagus.

Acid reducers decrease the amount of acid produced by the stomach. They help relieve heartburn. There are several types of nonprescription acid reducers on the market. Examples include H2 blockers (such as famotidine and ranitidine) and proton pump inhibitors (such as lansoprazole and omeprazole). Each has slightly different cautions for use. Read and carefully follow the instructions included with the package.

Antacid and acid reducer precautions

• Try to eliminate the cause of frequent heartburn instead of taking antacids regularly. For more information, see the topic Heartburn.
• Consult your doctor or pharmacist before taking an antacid if you take other medicines. Antacids may interfere with the absorption and action of some prescription medicines. Also consult your doctor if you have ulcers or kidney problems.
• Do not use antacids for more than 2 weeks unless you have talked with your doctor about taking them on a long-term basis.
• If you have a problem with the function of your kidneys or liver, you should be careful with using antacids. All drugs are broken down and removed from the body by the combined action of the liver and kidneys. If your kidneys are not working correctly, it is possible that too much of the drug will build up in your body.
• If you are on a low-salt diet, talk with your doctor or pharmacist before choosing an antacid. Some antacids have a lot of salt (sodium).
• If you are pregnant, antacids are safe to use for heartburn symptoms. But do not use antacids that have sodium bicarbonate (such as Alka-Seltzer). They can cause fluid buildup. During pregnancy it is okay to use antacids that have calcium carbonate (such as Tums).