Doctors are warning of a dangerous trend gaining popularity with teenagers on social media that has sent some to the hospital.

The "Tide Pod Challenge" calls for teens to eat the small laundry detergent packets, and then post video of the act online.

The pods, however, are highly toxic. Doctors say chewing them can cause permanent damage to the esophagus and even death.

"The esophageal burns can eventually burn through to the trachea or damage the esophagus so badly that they wouldn't be able to eat," says Dr. John Zaso, a pediatrician. "It's almost like biting into drain cleaner."

The American Association of Poison Control Centers says about 40 cases have been reported this year so far.

Health experts recommend contacting a doctor immediately if a pod is ingested.