Button batteries are small round, silver batteries found in lots of electrical toys and devices.
If your child swallows a button battery or you think they may have swallowed one, take them to A&E straight away.
As well as being a choking hazard, button batteries can cause internal burns, internal bleeding, and in some cases, even deaths.
They can also cause burns if they're lodged in a child's nose or ear.
The Child Accident Prevention Trust website has more advice about button batteries.
Click or touch the image below to view a button battery information sheet.
In this film, George Asan talks about his daughter Francesca, who died after swallowing a spare button battery.