Nesheiwat told Fox News anchor Eric Shawn that she's seen young patients with chest pain, shortness of breath, and even collapsed lungs.
"What these kids and teenagers are doing — they are inhaling these harmful chemicals and toxins into their lungs … their lungs become inflamed, they get filled with fluid, and they go into respiratory distress. They can't breathe," she said while appearing on "America's News HQ" on Saturday.
Her comments came after health officials have linked several deaths and hundreds of cases of lung illness to e-cigarette products. Juul, a prominent vaping vendor, has maintained that their product is safe.
Nesheiwat told Shawn that vaping companies specifically target teens online, pushing flavors like fruit punch and cotton candy. Because teens' lungs are still developing, she said, vaping could be especially harmful to their age group.
It's unclear exactly how vaping affects the body given the amount and varying combinations of chemicals involved, she said.
"Kids are getting a hold of these products — they could buy them off the streets, they are counterfeit, bootleg marijuana mixed with other chemicals. We've seen vitamin E has also been linked as one of the chemicals that might be causing harmful effects in the lungs," she said.
"But it's not just one substance. It could be a mixture … that all together, you heat them up and it causes inflammation and severe lung damage," she added.
Health and Human Services Secretary Alex Azar previously told Fox News that people shouldn't vape and especially shouldn't alter the product with THC.
"Please be very, very careful," he said. "This can be extremely dangerous,"