Eighty percent of Americans get a daily jolt from caffeine, and now, as marijuana legalization has spread across the nation, some users and businesses have begun touting a combination of the two drugs.

“After years of smoking, I’ve found that caffeine and weed are a perfect mix. If I get nicely stoned then drink a strong cup of coffee, the effects mix so perfectly,” wrote one Reddit user.

A company called Cannabiniers recently tapped into the trend with the launch of Brewbudz, which are cannabis-infused coffee, tea and cocoa pods that pop into any Keurig coffee brewer.

But what happens when you combine the drugs, and are there possible dangers?

It’s important to keep in mind that the caffeine in a regular cup of coffee or tea is a pretty powerful psychoactive drug, meaning it’s capable of affecting the mind, emotions and behavior, Dr Sergi Ferre, a senior investigator at the National Institute on Drug Abuse (NIDA), told Live Science.

Caffeine exerts its effects by blocking receptors in the brain for a neurotransmitter called adenosine, Ferre told Live Science. Adenosine is an inhibitory neurotransmitter, meaning that it blocks other neurotransmitters that excite the neurons; its activity thus leads to feelings of fatigue. So, by blocking adenosine, caffeine changes peoples’ moods and leaves them feeling more alert and awake.