They can be deadly to children.

An 18-month-old girl has her 3-year-old sister Bailey to thank after surviving swallowing a toxic lithium battery, reports KCTV.

Bailey saw her sister swallow the button battery, and knew something wasn't right. "She went back to bedroom and told my husband what happened, 'Daddy, Daddy, she swallowed a penny!," mom Sarah said.

The battery got stuck in Shelby's esophagus. After only a short time, the outer coating had completely eroded.

Doctors at Children's Mercy Hospital removed the battery before it caused serious injuries.

Earlier this year, we told you about 2-year-old Elaina Redding who bled to death three weeks after swallowing a button-sized battery.

Pediatrician Dr. Cara Natterson says ingested batteries can be extremely dangerous for three different reasons:

• The battery itself can block the airway or the intestinal tract
• Batteries contain alkali, which can corrode tissues
• The voltage generated by the battery can cause a burn.

The National Capital Poison Center said more than 3,000 people of all ages in the United States each year unintentionally swallow miniature disc or "button" batteries. Ten percent of kids who swallow button batteries die, according to the poison center. That's because batteries lodged in the esophagus can cause severe burns in just two hours. Within six hours, the battery can eat through the esophagus or the organ it is lodged against, and within eight to 10 hours, it can cause death.

Symptoms in children include refusing to take fluids, an increase in salivation, vomiting, and abdominal tenderness. But in one study, nine of 25 patients had no symptoms at all. That's why officials say do not wait for symptoms to develop before getting an X-ray. If the battery remains in the esophagus, it must be removed immediately.

Experts warn not to give your child ipecac if he or she has swallowed a battery.

This story reminds us that common household items -- like batteries -- can pose very real risks. Remember to keep batteries out of the reach of young children. If you have an older child, remind him never to put a battery in his mouth under any circumstances.

Dr. Cara Natterson, a graduate of Harvard University and the Johns Hopkins School of Medicine, and author of "Your Toddler: Head To Toe," is a pediatrician and mother of 2. Her latest book is "Dangerous or Safe?"