According to the Centers for Disease Control and Prevention, tobacco use remains the #1 preventable cause of premature illness and death in the US. You’re probably well-versed on the ill effects of cigarettes on health, but what about hookah, or water pipe smoking?

It turns out that hookahs and cigarettes have more in common than you might think. Researchers at the University of California, San Francisco compared levels of nicotine and tobacco-related carcinogens, toxicants, and irritants in 55 healthy and experienced hookah users before and after smoking water pipe at hookah bars or lounges.

On average, after just one session of hookah smoking, users’ nicotine levels jumped 73-fold. This level of nicotine is high enough to contribute to addiction. That’s bad news for college students, as nicotine exposure as an adolescent or young adult increases risk for future nicotine dependence. And if that wasn’t enough, users’ levels of cancer-causing tobacco-specific nitrosamines (TSNAs) doubled, while their levels of benzene, an irritant, nervous system toxicant, and carcinogen, increased by 91%.

While the body of research on hookah smoking is still growing, the bottom line is that hookah smoking isn’t harmless. Next time you and your friends are making plans for the evening, consider that even occasional hookah use could increase risk for addiction and chronic disease.