An Illinois teen issued a stern warning to youngsters from his hospital bed to stop vaping — saying the habit has left his lungs looking like those of a man more than 50 years older.

Adam Hergenreder, 18, of Gurnee, cannot breathe without oxygen tubes since being admitted Saturday to a hospital in Libertyville with a “vaping-induced acute lung injury,” the Chicago Tribune reports.

The teen — who started vaping at 16, with mint and mango his preferred flavors — told the newspaper he ignored warnings to stop from teachers, parents and health officials until it was nearly too late. He was rushed to the hospital after days of uncontrolled vomiting — and faces up to months of recovery, with the possibility of permanent damage to his lungs from scarring due to inflammation.

“People just see that little pod and think, how could that do anything to my body?” Hergenreder said Tuesday from Advocate Condell Medical Center. “I’m glad I could be an example and show people that [vaping products] aren’t good at all. They will mess up your lungs.”

Hergenreder started out using about one and a half Juul pods per day, he told WLS-TV.

“When I first started Juuling, I didn’t know what nicotine was, so I just thought it was vape juice,” the teen told the station. “I don’t even know what vape juice is.”

Hergenreder then began vaping marijuana, buying devices from street dealers that can be altered or contaminated with unknown substances. That daily regimen led him to an emergency room, where a doctor ordered a scan of his stomach and saw that “something wasn’t right,” his mother told the Tribune.

“That doctor saved my kid’s life,” Polly Hergenreder said.

The teen’s condition has since improved thanks to the oxygen tubes, steroids and antibiotics, but he’s one of at least 27 patients in Illinois who have been hospitalized in recent weeks with severe respiratory illnesses, including one who died, according to the newspaper.

Health officials in Oregon on Wednesday also announced that a second person has died from a severe lung illness linked to vaping — and the first such death connected to a vaping product purchased at a marijuana dispensary.

A total of 215 possible cases of severe lung disease associated with e-cigarettes have been reported by 25 states as of late last week, according to the Centers for Disease Control and Prevention.

In a statement to The Post, a Juul spokesman said the San Francisco-based company takes the health of its users seriously, labeling its products with “ingredient disclosures” and health warnings.

“Our device and manufacturing facilities are subject to numerous quality and certification standards and we conduct extensive preclinical and toxicological testing of the ingredients and analytes in Juul e-liquids and aerosols,” the statement read. “Our testing is conducted through reputable, independent third-party laboratories, and shared with relevant regulatory bodies.”

The company is also working to stop counterfeit products compatible with its devices, which are often marketed in violation of Food and Drug Administration laws, according to the statement.

“As to this particular reported event, we do not have any details beyond what is being reported by the media, including what or whose products were actually consumed,” the statement read. “We will continue to vigilantly monitor for any evidence of safety issues.”

Hergenreder, meanwhile, hopes to leave the hospital in days if his condition keeps trending in the right direction. But only “time and further pulmonary testing” will tell if his breathing will ever return to normal in the weeks and months ahead, his doctor told the Tribune.

“I feel stupid,” Hergenreder told the newspaper. “I want other people to stop. It’s going to attack your lungs.”

With Post wires