According to Medicine Net, drinking small amounts of baking soda is harmless and may actually cure mild cases of heartburn or indigestion. It should never be consumed in very large doses as this can make a person sick, according to MedlinePlus.
The active ingredient in baking soda is sodium bicarbonate, an alkali substance often used to neutralize stomach acid. Arm & Hammer gives directions for using baking soda to relieve acid indigestion, sour stomach or heartburn. It suggests dissolving ½ teaspoon of baking soda in 4 ounces of water. This antacid mixture can be ingested every two hours, but no more than seven doses should be taken in a 24-hour period, or no more than three doses in 24 hours for people over 60. Arm & Hammer also advises people to check with a physician if they are using the product regularly for over two weeks to determine whether there is a more serious underlying problem. MedlinePlus warns that baking soda overdose is possible and cautions specifically against soda loading, the dangerous practice of drinking large quantities of sodium bicarbonate in the theory it helps with athletic endurance and performance. It does not, and soda loading may result in poisoning that requires treatment at a hospital.