can you blackout from weed

Why Does a Single Hit of Weed Make Me Faint?

One night in 2005, at a party at my house, two things happened: I had a single toke from a joint, and a friend introduced me to her new boyfriend. For most people this confluence of events would be no problem, but my body was not having it. As my friend’s boyfriend dribbled on about his adventures in Peru, his fluffy hair began to morph and swirl. The more it swirled, the more I wanted to vomit. Then his voice started piping down through a tiny hole in the roof, then… nothing. It was lights out. That was the first time it happened, but soon enough it became apparent that this was my fate. I could not inhale marijuana—not even a little bit, not even sans alcohol—without blacking out. But why? Is my constitution so delicate, just a whiff of weed requires its total shut-down?

One of the only studies conducted on this phenomenon was published in 1992. Researchers from Duke University gave ten healthy men a strong joint to smoke while standing up, and reported that six participants felt “moderate” to “severe” dizziness. Those who experienced severe dizziness also showed marked decreases in blood pressure, which went as low as 60 mmHg.

The standing-up part is key because it indicates weed could bring on something called orthostatic hypertension, low pressure caused by the movement or position of the body.

“Marijuana can cause quite profound lowering of blood pressure, and cause users to faint as not enough blood gets to the brain,” confirms Dr. Andrew Mongomery, a general practitioner. “A lesser lowering of blood pressure may lead to a sense of dizziness without actually passing out, [although] the biological mechanisms underlying this are highly complex and incompletely understood.

“Marijuana can also lead to anxiety,” he adds, “with a secondary effect of dizziness—or act on the brain directly to create a sense of rotational dizziness.”

Blood vessels dilate, causing the brain to be deprived of oxygen and thus blacking out.

Dr. Harry McConnell, a Professor of neuropsychiatry at Griffith University’s Menzies Health Institute, says the reason behind a weed-related fainting spell depends on the situation and the individual. Aside from a possible drop in blood pressure, “it could also be seizures that cause blackouts, or the other chemicals mixed with it. After all, Marijuana is not pure, so it might have recreational chemicals mixed with it. People may not be aware of those ingredients.

“Marijuana might [also] cause vasodilation,” Dr. McConnell continues, “where blood vessels dilate, causing the brain to be deprived of oxygen and thus blacking out. Sometimes episodes of vertigo can also cause blackouts.”

Then there is the possible effect of other recreational substances, possible other drug interactions, personal medications, or medical conditions. A study from 2002 noted that while weed’s “cardiovascular effects” are not associated with serious health problems for most young, healthy users, people with cardiovascular disease could be putting their health at risk. This is “because of the consequences of the resulting increased cardiac work, increased catecholamine levels, carboxyhemoglobin, and postural hypotension.”

Whatever the reason behind your body’s hatred of the herb, accept that the weed life may not be for you, and get yourself seen to. “[Fainting from marijuana use] is not certainly uncommon,” confirms McConnell. “It’s recognized. But it’s always important to go to a doctor and get evaluated.”

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One toke and I'm out.

College Kids Still Don’t Understand How Drinking Causes Blackouts

“This is a really important distinction.”В

The knowledge gained over four years of blackout drinking becomes a powerful tool as it’s passed down through the ranks of college students. But a new paper in the journal Psychology of Addictive Behaviors by scientists at the University of Missouri and Brown University highlights two major ways in which word of mouth may be letting students down.

Though studies demonstrating how certain drinking patterns can cause blackouts tend to happen on college campuses, not all of that information makes the jump from the lab to the party scene, often only blocks away. To quantify this, Mary Beth Miller, Ph.D., a clinical psychologist and the lead author of the paper, asked a focus group of 50 college students what they did and didn’t know about drinking behaviors that might lead to blacking out. She and her colleagues compared the students’ anecdotes to knowledge gleaned from scientific research. They identified two areas in which the focus group didn’t have the most up-to-date information when it comes to preventing a blackout.

“One, based on what we know right now, drinking speed is more important than actual drinking quantity in determining whether or not someone blacks out,” Miller tells Inverse. “The second thing is the confusion surrounding concurrent use of alcohol and other drugs.”

Speed Versus Quantity

The amount someone drinks obviously determines how the night may unfold, but Miller was surprised to find that most students didn’t realize that their rate of drink consumption is actually a greater risk factor than the amount of alcohol when it comes to blackouts.

This distinction has been described in more than one paper, but a 2009 paper in Environmental Research and Public Health describes it well. These authors suggest that “a rapid rate of increase in blood alcohol concentration (BAC) is most consistently associated with the occurrence of an alcoholic blackout.” Miller observed that the students didn’t seem to know this fact:

“It was interesting, though, that the importance of drinking too much came up much more often than the idea of drinking too fast,” Miller says. “This is a really important distinction, and one that may give young adults more control over their drinking if they really understood it.”

The Effects of Smoking Weed

Miller was also surprised to find that most college students weren’t exactly sure how smoking weed combined with alcohol to make them black out. Responses were all over the board: Some thought that smoking might cause someone to drink less, thereby avoiding a blackout. Others believed that it might not have any effect at all.

“I thought it would be more common knowledge that marijuana use, in general, would be expected to increase your likelihood of blackout; but some of our participants expressed strong opinions that marijuana decreased their likelihood of blacking out,” Miller says.

There is research out there indicating that combining weed with alcohol can impair memory (and contribute to blacking out.) For example, a statement provided by the National Institutes of Health indicates that combining THC — the psychoactive component in marijuana — and alcohol can lead to greater memory impairment than administering either one alone.

But there are still some issues when it comes to studying the effects of marijuana on memory, which might lead to some of this confusion. For one, it’s really difficult for US-based researchers to receive permission to study weed, and as a result, some well-publicized research on its effect on memory is based on results from synthetic cannabinoids, not THC or the plant in its natural form. Still, we don’t have evidence that it prevents blackouts either, as some of the students in the focus group claimed.

Given these two areas of confusion, Miller would offer her students one piece of advice to avoid blackouts: treat drinking like a marathon, not a sprint. For most students, focusing on spreading drinks out over an evening is probably the most expedient way to avoid blacking out:

“They will still get buzzed (or drunk, if that’s what they’re going for) if they have four drinks in two hours instead of one,” she adds. “If anything, the ‘fun’ part of drinking will last longer if they can spread that drinking out.”

"This is a really important distinction."