Crossfaded: What Happens When You Mix Weed and Alcohol

Crossfaded (or cross-faded) is slang for feeling the overlapping effects of alcohol and cannabis at once. That is the definition used in a 2022 study of young adults published in Psychology of Addictive Behaviors, which also cites research finding that 59% of US college students who drank in the past year had been cross-faded.

The key word is overlapping. Having a drink one night and using cannabis on another is not crossfading; the risk comes from both sets of effects hitting you at the same time.

Alcohol appears to raise the amount of THC that reaches your blood. In a controlled study published in Clinical Chemistry in 2015, adults who used cannabis occasionally drank either a placebo or a low dose of alcohol 10 minutes before vaping cannabis. With alcohol, peak blood THC was significantly higher at both cannabis doses: at the stronger dose, the median peak was 67.5 µg/L with alcohol versus 42.2 µg/L without. The researchers said this may help explain why the combination impairs performance more than cannabis alone.

Canadian health agencies reach the same conclusion. Health Canada says combining alcohol with cannabis greatly increases impairment, which raises the risk of injury or death from accidents. CAMH says the two intensify each other's effects and can cause severe impairment, including poor memory, judgment and coordination, as well as nausea and vomiting.

"Greening out" is slang for feeling faint and vomiting after using cannabis, a reaction also called a whitey. Add alcohol and the list of likely problems grows.

When the 2022 study's researchers interviewed 36 young adults about mixing, the most common problems were vomiting (reported by 64%), nausea (44%), the spins or dizziness (44%), hangovers (39%) and blackouts (36%). Participants usually described vomiting and nausea as worse when they mixed than when they used either substance alone.

Cannabis on its own can also cause anxiety, fear or panic, a drop in blood pressure that can make people faint, and a faster heart rate that can be dangerous for people with heart conditions, according to Health Canada's overview of cannabis effects. If anxiety or panic is a pattern for you, weed and mental health covers it in more depth.

Folk advice says drinking first is the rough order, but the evidence does not point to a safe one. The lab study gave alcohol before cannabis and found higher THC levels. Yet in the 2022 interviews, many participants said using cannabis first and then drinking made them more likely to feel sick. Health Canada's warning is about the combination itself, whichever comes first.

Edibles add a timing trap. CAMH notes that edibles can take up to 2 hours to show effects and can last up to 12 hours, and it suggests waiting about 4 hours before deciding on another dose. An edible can therefore peak after you have kept drinking. The stages of being high explains how a high builds over time.

The Criminal Code prohibits driving while impaired to any degree by drugs and alcohol, and it sets a specific limit for the combination: 50 mg of alcohol per 100 ml of blood plus 2.5 ng or more of THC per ml of blood, within 2 hours of driving. That alcohol level is well below the 80 mg mark where alcohol-only penalties start. A first offence carries a mandatory minimum $1,000 fine, a second at least 30 days in jail and a third at least 120 days.

Impairment can also outlast the high. Health Canada says cannabis impairment can last more than 24 hours after use, and that THC affects coordination, reaction time, attention, decision-making and the ability to judge distances. It also links cannabis to accidents while biking and skiing, not just driving. Sort out a ride home or a place to stay before the night starts.

Some signs mean a person needs urgent help. For alcohol poisoning, the Public Health Agency of Canada uses C.U.P.S.:

Talk to the person or gently shake them to see if they respond. If they do not, call 911. If they cannot sit up, lay them on their side in the recovery position to prevent choking, do not leave them alone, and try to find out what else they took and how much.

For advice on a suspected poisoning, call a poison centre at 1-844-POISON-X (1-800-463-5060 in Quebec), the number Health Canada lists, or call 911 in an emergency. Tell them that both cannabis and alcohol were involved.

If you take prescription medication or have a heart or mental health condition, ask a doctor or pharmacist before using cannabis, especially alongside alcohol.

Not mixing is the lowest-risk option. If cannabis is part of your plans anyway, these habits cut the risk:

GasDank delivers cannabis same day across Toronto and the GTA, usually within 1 to 2 hours, and ships by mail order across Canada. Customers must be 19 or older (21 in Quebec), with ID checked at the door. Toronto weed delivery has the delivery areas and order details. Whatever you order, keep it on a separate night from alcohol.