The electronic cigarette or e-cigarette we know today was invented by a Chinese pharmacist named Hon Lik in 2003.

When first sold in 2004, e-cigarettes were marketed as a healthy alternative to smoking since the e-liquid generating the smoke-like vapor was claimed to contain small quantities of nicotine. Vaping was claimed to help tobacco smokers quit smoking.

In the 15 years since, e-cigarettes are still with us but in enormous numbers, and they are mostly made in China. But the health dangers posed by vaping are now more clearly understood.

The verdict by doctors and scientists based on a growing body of knowledge: Vaping is dangerous to the health of users and might be more dangerous than smoking tobacco in the long run.

Researchers such as Maciej Goniewicz, one of the leading e-cigarette researchers based at Roswell Park Comprehensive Cancer Center New York, are now finding out that e-cigarettes may be more dangerous than expected, especially for the heart, lungs and brain. They’re also trying to determine what impact vaping has on developing bodies and brains.

What these researchers agree on is that vapers are overwhelmingly young people who are in their teens up to early 30s. And many vapers weren’t even smokers when they started the habit, a clear indication vaping is indeed addictive.

Researchers also agree that vaping is a health danger. And why is this so?

Among the most serious dangers posed by vaping is a probable link to an increased risk of seizures because a lot of e-liquids today, especially Juul (the market leader) contain too much liquid nicotine. Juul has even admitted that one of its e-liquid pods is equal to a pack of cigarettes in terms of nicotine.

The U.S. Food and Drug Administration (FDA) has warned that nicotine-induced seizures could be a side effect of vaping, albeit a rare one. There have been at least 35 reports of seizures in the U.S. over the past decade following e-cigarette use.

Although this number might not seem large, it is disturbing since it opens the possibility that an otherwise healthy user might be stricken by a sudden, life-threatening seizure. Researchers have long known seizures can be a side effect of nicotine poisoning.

“While 35 cases may not seem like much compared to the total number of people using e-cigarettes, we are nonetheless concerned by these reported cases,” FDA administrator Dr. Scott Gottlieb said. “We also recognize that not all of the cases may be reported.”

Dr. Gottlieb noted the FDA is calling for more investigation into whether there is a connection between vaping and seizures. It urges doctors and the public to come forward if they know about cases.

Doctors also said the nicotine in e-cigarettes may stress the cardiovascular system.

“Nicotine (in e-cigarettes) does the same thing as (tobacco) cigarettes,” Dr. Neal Benowitz, a professor of medicine at the University of California San Francisco who studies the link between e-cigarettes and heart health, said.

The nicotine in an e-liquid can boost the adrenaline in our bodies and activate the sympathetic nervous system (or the “fight or flight” response). This raises blood pressure and accelerates the heart rate, causing the arteries carrying blood away from the heart to narrow.

The U.S. Centers for Disease Control and Prevention (CDC) has never stopped warning about the dangers posed by nicotine to young people, whether this nicotine be in an e-cigarette or in a common tobacco cigarette.

CDC affirmed most e-cigarettes contain nicotine, which can harm the developing adolescent brain. It said the brain keeps developing until about age 25. Using nicotine in adolescence can also harm the parts of the brain that control attention, learning, mood and impulse control.

The center also pointed out that young people who use e-cigarettes might be more likely to smoke cigarettes in the future.