As Jacob* sits in his third period class, his head begins to pound. His teacher is lecturing, but he cannot focus. Instead, his mind is on one thing: getting to the bathroom.

The headache grows increasingly unbearable; he slips out under the guise of using the restroom. There, he pulls out his Juul, a form of e-cigarettes that has grown increasingly popular amongst high- and middle-schoolers, and sneaks several puffs behind the stalls. His hands start to tingle and his head starts to spin, and he comes back to class, overwhelmed by the feeling of relief.

At first, Jacob did not get cravings. Prior to getting his own device, he said he could control his usage.

But after getting his own Juul, the cycle of cravings and relief became all too familiar. He said he first felt addiction after he finished one or two packs of pods, or refills. As of now, he has been consistently using his Juul for a little over a year.

Almost every day, he goes through the same series of headaches. Almost every day, he sneaks off to the bathroom during class, and almost every day, he takes enough puffs to get “domed,” a nickname for the high received from nicotine. He said he goes through a pod, which Time magazine reports has the same amount of nicotine as a pack of cigarettes, per day.

Due to the amount of nicotine present in a Juul cartridge, researchers such as Dr. Michael Ong, an associate professor at the David Geffen School of Medicine, say it is easily addictive.

These devices were originally intended to help adult smokers quit cigarettes, but have since spread in popularity amongst young people. Part of the reason for this popularity is the fact that Juuls come in what the Boston Globe describes as “kid-friendly flavors,” such as fruit medley and mango.

Although these devices don’t contain the same carcinogenic smoke as tobacco and contain fewer toxic substances than regular cigarettes, the Center for Disease Control (CDC) warns that using e-cigarettes like Juuls can still expose users to cancer-causing chemicals. Furthermore, a study by scientists at the Harvard T.H. Chan School of Public Health found that diacetyl, a chemical found in most of the popular flavors, can cause bronchiolitis obliterans, a severe respiratory disease.

But when he took his first puff, Jacob didn’t know that. All he knew is that his friends did it, so he felt he could, too.

“My friend got one, and he was like, ‘oh, this is the new thing, it gets you domed,’ so I said okay,” he said. “Then I got my own.” But now, the cravings are hard to resist, despite the fact that the negative effects of his addiction have already permeated his daily life.

More recently, Jacob’s addiction has led to problems with his familial relationships.

“I’ve gotten caught [Juuling], and they’ve taken my stuff,” he said. “It starts fights.”

In addition, Jacob said that his habit interfered with his sports, despite his previous passion for them. Now, that passion is waning as he falls behind the rest of his team.

“I can’t breathe as [well],” he said. “I used to be good, but [now] I get tired super easily. [Juuling] made me get more out of shape, and [now] it is a little harder to get back into shape.”

Similarly, Brian* uses his Juul device often. He began when a friend of his suggested they sneak off to the bathroom to try what they were told was the latest trend, and since then, he hasn’t stopped. He said he uses it several times a day every day, sometimes at school.

“I Juul during class sometimes, if I have one on me,” he said. “[If not], I’ll just ask my friend for his.”

The habit isn’t cheap. Brian said he has spent close to $500 on his habit in the past year.

Just like Jacob, Brian said he sometimes takes breaks from using his Juul device.

According to him, these breaks come with their own set of symptoms.

“I take breaks when I don’t have any [Juul refills] or want to lower my tolerance,” he said. “When I take breaks, normally I’m a little moody.”

In addition, he described feeling the same nausea that Jacob experienced when he takes a break from his Juul.

Because Juul devices resemble USB ports with dark colors that are hard to identify, and produce less smoke than regular cigarettes, they are easy to disguise during class.

Brian said that he hides his usage during class by holding the smoke in his mouth and letting it out slowly, while it is difficult to see.

Jacob also uses his Juul device during school, a trend he is in the process of trying to break.

“I used to have an off-roll because I dropped a class, and so I would just go to the bathroom and Juul,” he said.

However, after Jacob sold his device to earn extra money, he decided to take a break. Although he does not plan to quit completely, he said he wants to spend this time focusing on getting his driver’s license instead, as his family won’t allow him to take his test until the Juuling stops.

Although he has yet to fully kick his habit, Jacob said he stopped bringing any Juul devices to school. He has admitted to his addiction, and says he is committed to attempting a break.

“The break makes me breathe [better],” he said. “At first I had headaches from not having it, but [now] I’m feeling the same [as before].”

Now, he has stopped sneaking off to the bathroom during school. Now, he misses less class time. Now, the headaches are becoming more bearable and the air more breathable.