MINNEAPOLIS (WCCO) — Vaping might seem a popular thing to do, but it’s sending kids to the hospital.

Minnesota’s Department of Health has a strong warning to parents and teens about serious lung damage due to vaping.

READ MORE: Semi Driver Killed In I-94 Crash In St. Michael, State Patrol Says

Children’s Hospital is now treating at least four teens for serious lung damage. And in Wisconsin, 25 more kids are getting medical care for similar symptoms.

As WCCO’s Bill Hudson explains, experts are calling it an epidemic.

When E-cigarettes first came on the scene, many saw a safer alternative to smoking tobacco.

Inside Children’s Hospital lies proof that they’re not.

“Their symptoms look like common infections and they just don’t get better,” explained Dr. Ann Griffiths, Pediatric Pulmonologist at Children’s Minnesota.

Four teens are being treated at Children’s for pulmonary disease.

Dr. Griffiths says the vaping epidemic is causing serious damage.

“The lungs are struggling to deal with chemicals that are being inhaled and the body’s way of handling that is to send more and more immune system to the lungs to get rid of something it is struggling with, so all that inflammation is causing injury,” explained Dr. Griffiths.

READ MORE: Man Charged With Murder In Gunfight-Turned-Crash That Killed Autumn Merrick, 18

Inhaling the battery-heated, vaporized chemicals can lead to shortness of breath, fever, coughing, dizziness and chest pain.

RELATED: Tests Can Reveal If Your Teen Has Been Secretly Vaping

“The smells are easier to hide than cigarettes,” explained Tracee Anderson with Minnesota Teen Challenge.

By design, e-cigarette marketing is clever. Devices can be hidden in the drawstrings of a hoodie.

It’s why Minnesota Teen Challenge will alert parents to the dangers at their state fair booth.

“It’s like a habit, they’re ingesting so much of it we’ve seen a couple of cases where it’s called nic sick, where students are passing out in school,” Anderson said.

E-cigarettes have surpassed conventional smoking among teens. One in five vape regularly. But what’s most alarming, is how quickly vaping is landing young users in hospitals.

“This is exposure for a short period of time relatively speaking, and really severe early injury that’s so worrisome,” said Dr. Griffiths.

Another big concern is for the long term damage to the lungs in such young patients.

MORE NEWS: Stray Bullets Hit Daycare, Multiple Homes In Brooklyn Park

Doctors are hopeful for patient recoveries, but since this is all so new, they simply do not know.