Last November, an e-cigarette exploded in Cordero Caples’ face, breaking his neck, fracturing face bones, shattering his teeth, and burning his mouth, according to Caples’ sister, who spoke to The Denver Post. He lived through the ordeal, but he’s seen better days. “He has a hard time moving his body,” his sister Colessia Porter said. “How much of a range of motion he’ll have is something we just don’t know.”

This isn’t the only case of an e-cig taking a bite out of its user. They’ve ignited in people’s pockets, necessitating skin grafts in at least two cases, they’ve squirted battery acid and burning debris into smoker’s mouths, and set a bed on fire, according to the Post.

The risks of blowing yourself up while ripping on a vape pen are slim. Of the estimated 2.5 million e-cig users, roughly 30 have been documented (though that small number might reflect substantial under-reporting and failure to find all the cases that have been reported).

The real trouble is that not enough is known about the danger that e-cigs present. Many explosions seem to result either from using the wrong battery charger on an e-cigarette or from putting an e-cig in a pocket next to some coins, which react with the battery, causing it to swell and then explode.

“I’m totally on the fence about them,” Alexander Shonkwiler, who received skin grafts for an e-cig battery burn, told the Post. “It was a totally freak accident. But I also have that fear I’m going to blow my face off. I might just go cold turkey instead.”

Dr. Anne Wagner, who treated Shonkwiler at the University of Colorado Hospital Burn Center, said she’s seen three other cases of e-cigarette burns at the clinic in the last two months alone. “I don’t think people realize the dangers of these things,” Wagner said. “I definitely have not seen four people being hospitalized for their cigarettes being on fire.”

All of this applies to hash oil pens in an interesting way. The fuzzy legality of buying, selling, and using hash oil pens across the country could mean there are a substantial number of hash oil pens which explode but don’t get reported, since the user could be admitting to breaking the law if they’re in one of the many states and municipalities where using cannabis is still a crime.

At the same time, the nearly non-existent regulation of cannabis products in general means that it’s not too unlikely that vape pens could be made even more shoddily than their tobacco counterparts. So, the same advice can be applied to a vape pen as to hash oil or flower: only buy the good shit.