Antacids are medications used to treat digestive symptoms, such as heartburn, sour stomach and acid indigestion. They raise the pH level (measure of the degree of acidity or alkalinity) of the stomach from highly acidic to a more neutral level. This neutralizes acid in the stomach and can provide substantial relief from symptoms.

The major types of antacids include:

• Aluminum and magnesium. Aluminum salts dissolve slowly in the stomach and work gradually, providing longer-lasting relief. Magnesium salts act quickly to neutralize acids.
  
  
• Calcium carbonate. Also known as chalk, it acts quickly and neutralizes acids for relatively long periods of time.
  
  
• Sodium bicarbonate. Also known as baking soda, it works quickly to neutralize acid.

Antacids are available in oral suspension, tablet, gel, lozenge and liquid form. They are available in a variety of flavors ranging from mint to assorted fruit. They begin to work within a minute, and can provide relief for time periods that range from 10 minutes to more than 90 minutes. However, they typically do not treat the underlying condition causing the symptoms. Therefore, patients who experience symptoms of digestive upset for more than two weeks should seek medical assistance.

Certain medications are known to interact poorly with antacids. In addition, antacids may worsen some pre-existing medical conditions, including colitis, constipation and hemorrhoids. It is recommended that children, elderly people and pregnant or nursing women consult a physician before taking antacids.