A button battery is one of those flat round batteries that are found in remote controls, key fobs, children's toys and singing greeting cards. They come in many sizes and resemble a coin. They are dangerous when swallowed because they can become lodged in a child's esophagus and cause erosion and damage within hours.
If you suspect your child has ingested a button battery they need to have an x-ray immediately. The x-ray will determine where in the body the battery is located. From there, a doctor can determine what needs to be done.
Button batteries found in the esophagus need to be removed as soon as possible by a physician. Do not make your child vomit if you suspect they have ingested a battery. Similarly, do not give the child anything to eat or drink if you believe they may have swallowed a battery. For more help, call your local Poison Control Center at 1-800-222-1222. Be sure to properly babyproof your home.