Transcript for Teen was in the fight for her life after vaping a cartridge a day
Reporter: You hid your vape under your pillow. And you gonts how long? I couldn't go without ten or 15 minutes. Reporter: She never expected that what she thought was a harmless habit, vaping, would end um nearly killing her. It took two days for my lungs to fail. Reporter: A tube still pumping oxygen to her failing lungs. In her hands, a call to action. I asked for a pen and paper. That was the only way I could communicate. I wrote I wanted to start a no-vaping campaign. Reporter: Sima's story is the latest in a landslide of incidents linked to vaping, sparking what many are calling a national health crisis. What we've seen in the past month is an increased number of people coming in with respiratory problems as a result of vaping. Reporter: So far the senders centers for disease control report 450 possible cases of illness linked to vaping and deaths in Oregon, California, Illinois and Kansas. The CDC issued a stark warning. If you are vaping, no matter how old you are, you should consider stopping. I didn't think of myself as a smoker. The vaping makes it seem like it's nothing, like you're doing nothing wrong. Reporter: Sima was in high school when she started vaping nicotine. I was 15 when I bought it. I was like, could I get a pack of Juul pellets, and they said how old are you? And I said 22. They said okay. It ended up being my oxygen. I couldn't live without it. Because all my friends were doing it and nobody had symptoms like I had I wouldn't have imagined that maybe this is killing me. Reporter: Sima was an active, healthy teen. She'd been dancing for years, even making dance team the freshman year of college. But as her vaping habit increased, her ability to dance disappeared. She was smoking a cartridge a day. The same as a pack of cigarettes a day. Her parents had no idea their daughter had become hopelessly addicted. This healthy dancer stopped dancing because of it. Stopped living because of it. Stopped going to school and college because of it. Reporter: Sima said she was feeling sick all the time. Over a year I lost about 50 pounds without trying. Reporter: 50 pounds. Yes. Reporter: She stopped going to college classes. Her health issues were getting worse but no doctor could nail down what was wrong. Did you not tell the doctors that you vaped? I actually did. I made sure every hospital, every er, every doctor's office I went to, I told them that I Reporter: But you didn't tell them, I can't breathe, I feel like I'm going to die, maybe it's because I'm vaping. No doctor ever said maybe you should stop vaping. Reporter: It came to a head on August 15th when sima's dad rushed her to the er. I said go fast. Don't let me close my eyes, don't let me fall asleep or I won't wake up. Reporter: Why did you say that? Because I knew I was dying. Reporter: You felt death on you? Yes, it was terrifying. The worst part was I couldn't let it, like my parents watch it happen to me. Reporter: What hospital staff couldn't figure out why she couldn't breathe. Two days later doctors had to put her on a ventilator. I was begging them, vent her faster, vent her faster. She's going to die. Reporter: It was in that moment her cousin revealed her secret addiction. She said you know she smokes every day. I said what? What are you talking about? She smokes every day. She smokes that vape. Said you go tell the doctors right now. And I ransacked her room. They looked like candy wrappers, little cute mascara wand. Reporter: Dr. Kathryn is a pulmonologist and worked on sima's case. This was sima's chest X ray when she came into this this hazy white area just show that she could have a pneumonia. If we choose an X ray from less than 48 hours later, now her lungs, all of this white haziness here is inflammation from just day one to day three is remarkable. Reporter: The doctor is on the front lines of what health officials fear is an emerging crisis. The national youth tobacco survey found a 78% jump in e-cigarette use in students alone. Part of it is heating oil and inhaling oil. That's not something the body is used to inhaling. With that comes an inflammatory reaction that produces phlegm and sputum and gives it the wet cough property. Reporter: That sounds terrible and dangerous. Yes. Reporter: Last month, 17-year-old Tristan described how he spent 18 days in the hospital fighting for his life after vaping. I woke up throwing up everywhere. My heart was pounding out of my chest. Reporter: Tristan lost 15 pounds and said he had to re-learn how to walk. And just yesterday a Texas teen had to be rushed to the hospital after vaping at school. He hit it. He passed out and would not wake up. Reporter: In Wisconsin today, a man was arrested for making thousands of illegal thc vaping cartridges. The state of New York is taking an aggressive approach in an attempt to find answers and crackdown on black market products. You shouldn't be Saudi arabiaing products thaw don't know what you're smoking or vaping. Reporter: Many vaping products are popular with teenagers, but no company has taken more heat than Juul. They say it's designed to get adult smokers off cigarettes. Fwhu week, the fda sent a letter to Juul accusing it of marketing them as safer without proof. Juul responded saying we share these concerns about youth vaping. They shut down their Instagram accounts and began deploying new technology. The fact that they market this crap to children and they turned into pretty pink packaging candy pisses me off. There's a lot we don't know. So I would just say don't. Reporter: In the weeks since sima has worked to rehab her lungs. I don't necessarily crave the nicotine or the weed. It's craving the act of smoking. Reporter: But she hopes going public with her story can help keep her and countless others what would you tell somebody who's thinking about vaping and says I'm just going to try it one time to see what it's like. I would show them my pictures and say I tried it once, too, and I tried it another time and then another time. It's just remembering that you don't need it, like it's going to kill you. Reporter: For "Nightline," Adrian bank kert in Los Angeles.
This transcript has been automatically generated and may not be 100% accurate.