"Then in the morning I saw this awful burn on her leg," Retter said. "I was so shocked a phone case could do that. Doctors have said it is a severe chemical burn and she will be scarred for life. I can't believe it. She will have a scar in the shape of a phone on her leg."
Karly Retter made a Facebook post warning others about the cellphone case, which sells for $8.62.
"This case is full of acid and if it cracks it will cause third- to second-degree burns," she said "A lot of girls have these at the moment so just be careful."
The post has been shared over 45,000 times.
Rettet said her daughter's phone case comes from New Look. She said she called the customer service department of the UK retailer multiple times and did not receive help.
"New Look has spoken with the customer involved and takes complaints of this nature extremely seriously," a spokesman for the store said. "In line with our health and safety procedure, we have now instructed all stores to remove the product in question from the shop floor with immediate effect."