You may have learned the term “cross-faded” back in high school or college to describe the feeling when you’re both high and drunk. The combination of alcohol and cannabis creates its own effect, distinct from the effects of the two substances on their own. Cannabis and alcohol could influence both how each other’s chemicals play out in your body, as well as your behavior toward either or both of the substances when under their simultaneous influence.
Some research suggests that alcohol can increase the levels of THC (weed’s psychoactive chemical compound) in your blood, while other research indicates that people tend to drink less when they’re already high. In one study from the American Association for Clinical Chemistry, researchers determined that THC sans alcohol was concentrated in the blood between 32.7 and 42.2 micrograms per liter, while in the presence of alcohol increased to between 35.3 and 67.5 micrograms per liter. While these results may seem incidental, the researchers suggested that the interaction of THC and alcohol could have an effect on one’s ability to drive under the influence. Even if a person’s blood alcohol content is under the legal limit, they may be more impaired than normally under the influence of THC.
In another study from the National Institute on Drug Abuse (NIDA), researchers looked at differences in alcohol and cannabis consumption when either one or the other, or both were available. They found that almost 90 percent of subjects drank less alcohol when both were available, as opposed to when only alcohol was available, while meanwhile also discovered that 75 percent of subjects used more cannabis when both were available, as opposed to when only cannabis was available.
So while most people drink less alcohol when they’re also using cannabis, those who have already gotten drunk to the point of vomiting or feeling nauseated need to be careful. Cannabis can inhibit nausea and vomiting — hence why it’s good for chemotherapy patients — and therefore increase the risks of alcohol toxicity by preventing you from throwing up.
Generally, crossfading isn’t all that risky if you’re conscious of how much you consume, and don’t drive afterward. The effects of cannabis tend to be more cognitive, influencing your perception of time and space, while alcohol influences the central nervous system, with consequences on your physical coordination. It’s generally suggested that if you don’t want to “green out” (feel sick after getting high) start with the weed before you begin drinking. The alcohol could magnify your THC high, so best to know how the cannabis affects you before you introduce new chemicals. As the classic stoner aphorism goes, “Beer before grass, you’re on your ass, grass before beer, you’re in the clear.”