MONTREAL - A Montreal teenager recently spent 10 days in hospital after accidentally ingesting a button battery while chewing the tip of a pen flashlight, according to the Montreal Children's Hospital.

He suffered serious internal burns and a perforation of the esophagus.

The hospital cites the incident to warn that swallowing button batteries, the small circular batteries that power watches and other small electronic items, can lead to serious health problems and even death among children,

Once swallowed, the batteries can generate electrical power and release chemicals that can severely damage tissues in less than two hours.

A person who swallows a button battery must be given immediate medical help.

The battery can fit easily into the esophagus, larynx, pharynx, trachea or stomach.

Ingestion can cause esophageal perforation, bleeding, infection, damage to vocal cords and even death.

Increasing numbers of children and adolescents have suffered serious complications due to swallowing of these batteries, probably because these small cells are becoming more common.

The batteries are found in such items as musical greeting cards, certain children's books, watches, toys, hearing aids, cameras and digital planners.

With files from The Canadian Press