Warning: Graphic images.
A man in the United States has taken to social media to warn people about the potential danger of using a Fitbit watch.
Ethan Landers claims his watch exploded while he was sleeping, leaving him with nerve damage and a third-degree burn.
"I was sleeping when I woke up in a panic to my wrist burning," he wrote on Facebook. "I quickly realized my Fitbit was burning up so I tried frantically to get it off."
He said he quickly jumped out of bed and his wife helped him remove the watch.
"It felt like it melted through my arm. There was smoke coming out of the Fitbit battery and our bedroom smelled like an electrical fire."
After calling an on-call nurse, Landers was told to head to the hospital emergency room, as the wound was "white and already blistering".
At the hospital, the wound was cleaned and an x-ray was taken to ensure there was no debris still in his arm, he said.
He was later referred to a specialised wound clinic where he was informed he had a third-degree burn.
"I do not have feeling in parts of my wrist due to nerve damage and I will have a large scar that will be with me the rest of my life," Landers wrote.
"This was a traumatic experience and I hope no one else has to go through it. So, if you own a Fitbit, please reconsider using it."
A spokesperson for Fitbit confirmed to The Sun newspaper that the incident had been raised with them and they were investigating.
The company said their products undergo extensive testing to ensure they are safe.
"We have spoken with the user and are actively investigating this issue."