Deciding to take acid (the commonly used name for the psychedelic compound LSD) is a commitment. There’s a reason we call the experience a “trip”—the drug will take you somewhere, even if you don’t leave your house. Unlike a vacation or road trip, the mental and spiritual experience of tripping on acid doesn’t have an easily fixed beginning and end. Rather, the number of hours you’ll spend tripping varies greatly depending on a bevy of factors. The drug also affects your subjective experience of time, so a trip might feel shorter—or, more likely, longer—than it actually is.
Many familiar with taking acid have likely had the experience of a seemingly endless trip, for better and for worse. A brief moment spent looking at a beautiful flower might feel like a timeless experience, but so too might the waves of overwhelm, paranoia, or anxiety that sometimes arise. At some point, you might find yourself wondering: “Is this ever going to end?!” The answer is, undoubtedly, yes. Acid eventually wears off, and while it may profoundly affect your outlook on life, undesirable long-term effects are actually quite rare. We talked to experts and looked at the science to better understand how long you can expect to be “away” on your acid trip.
So, How Long Does An Acid Trip Last?
Lysergic acid diethylamide (LSD) is a powerful and long-lasting psychoactive substance that causes radical changes in perception and thought. Its effects are unpredictable, and scientists have different ideas about its exact duration, which varies based on dose and factors like environment, tolerance, and more.
Most LSD trips last between eight to 12 hours, with the peak typically occurring after two to four hours. In some cases, however, the effects can linger or re-appear for up to 24 hours, according to Bryan Roth, a pharmacology professor at the University of North Carolina School of Medicine and co-author of a 2017 Cell study on the biological mechanism behind LSD’s action in brain cells. (Roth does not recommend taking LSD except under controlled clinical trial settings. Remember that the drug is an illegal substance in most jurisdictions, including all of the United States).
Bill Richards, a psychologist at the John Hopkins University School of Medicine who has studied psychedelics for five decades, says that those orally ingesting a medium to a high dose of LSD will see effects appear after about 20 to 40 minutes, peak between the third and fifth hours, and then slowly return to ordinary consciousness. He says LSD tends to have a long “tail,” and the effects can be like a “bouncing ball” for several hours. (Richard’s expertise is specifically in the therapeutic use of pure LSD. This is a good time to remember how important it is to test your LSD—and other drugs.)
Whether you’re enjoying or feeling challenged by your trip, worrying about how long it will last is normal. Vanessa Cruz, a nurse who serves as a volunteer supervisor at the Fireside Project’s psychedelic peer support line, says they receive calls “all the time” from people who are hours into a trip and wishing the effects would end. Asking when they took the drug and offering general feedback, such as whether they’ve already passed the peak of the experience, are among the best ways Fireside volunteers assist callers. “Depending on their state,” Cruz tells DoubleBlind, “telling them a specific timeframe can cause more anxiety, so we speak in general terms like ‘it’s gonna start getting a lot easier from here.'”
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What Factors Contribute To The Length Of An Acid Trip?
The length of the trip varies based on factors like the dose taken, a person’s tolerance, their metabolic rate—and their set and setting. Set and setting refer to the general state of your mind, body, and environment during and before your trip. People who have taken LSD recently or frequently can develop tolerance, but tolerance tends to dissipate if you wait several days between uses. In most cases, higher doses will cause longer-lasting and more intense trips. But LSD is powerful enough to potentially have effects at “vanishingly small doses,” as Roth told Wired in 2017, after his group’s study found that microdose-sized quantities activated serotonin receptors synthesized in a Petri dish.
Someone concerned that their trip is going on too long shouldn’t smoke cannabis, says Cruz. Although some people feel the herb calms them down, it has a strong chance of re-activating psychedelic effects.
Your environment also plays a role. Cruz says Fireside Project volunteers are trained to ask concerned callers where they are. “If they’re at a concert or party or in a room with people they don’t know, we might ask if they have a way to safely leave the concert or go into another room,” she says. “Being in a space of comfort or quiet that isn’t so overwhelming, where they might have blankets and control over the environment,” can make a trip feel less intense, even if it hasn’t yet ended, says Cruz.
Intention is yet another factor, adds Richards. “LSD opens a door,” he says. “How long the door remains open depends to some extent on personal motivations—perhaps the way some will try to keep a toboggan moving at the bottom of a hill.”
Why Does LSD Last So Long?
Acid is a complex molecule that interacts with multiple neurological receptors. LSD molecules leave the bloodstream in a matter of hours. Yet, in 2017, Roth’s team found that LSD molecules wedge themselves into the brain’s serotonin receptors at an unusual angle. This unique binding mechanism helps explain why the effects of acid can last far longer than those of other psychedelic drugs like psilocybin mushrooms; psilocybin’s effects usually wear off in closer to six hours. (It’s important to note that some experiential characteristics of psychedelic trips, like time dilation, can change your perception of how long the journey lasts—and ultimately where your mind travels during the experience).
As Roth told Wired in 2017, “once LSD gets in the receptor, you can think of it as a hole in the ground. LSD jumps into it and then pulls a lid down over the top … it can’t get out.” That’s why it lasts as long as “12, 18, maybe 24 hours,” he said. However, that “lid” does move around, so LSD molecules eventually escape and become vulnerable to breakdown by enzymes, causing the high to wear off.
The half-life of LSD is approximately five hours, meaning that it takes five hours for half of the drug to be metabolized and eliminated from the body. This means that even after the peak of the trip has passed, there will still be enough LSD in the body to produce significant effects for several hours.
Does LSD Permanently Change Your Brain?
After taking acid, it is normal to feel lingering effects, including cognitive changes that may endure for days, weeks, or (rarely) years. According to the limited research available, enduring effects are usually not the ones that cause feelings of overwhelm or anxiety during the peak of a trip. A study published in Cell Reports in 2018 found that psychedelic drugs change the structure of neurons in animals and lab dishes and also increase the number of synapses, or connections, between neurons. If these findings hold true in humans, it might imply that psychedelic drugs have benefits like repairing brain networks damaged by conditions like anxiety and depression, according to study author David Olson. In other words, the long-term effects of LSD could be therapeutic.
Frightening long-term effects are possible, though rare. It’s possible that LSD may increase the risk of developing psychosis, but only in people who are already at heightened risk. This is not just associated with so-called “bad trips,” but can result from any LSD trip. (On the other hand, a 2015 survey published in Nature found no link between psychedelics and psychosis, suggesting that this connection may be one of correlation rather than causation.)
There are widespread urban legends of people who “never came back” from their acid trips. The only documented long-term effect of LSD bearing any resemblance to this myth is a hallucinogen-persisting perception disorder (HPPD), first described in 1954, which can involve brief “flashbacks,” or re-experiencing certain sensations from a trip. “There might be a general sense of altered perception, or visual things like static in their vision or the road starting to look wavy like it would if you were still on LSD,” says Cruz. Seeing intensified colors, fractals, and visual “trails” are other possible residual effects.
In most cases, these after-shocks only occur once or twice in the first few days after use, but in rare cases, people find them chronically “waxing and waning” over months to years, according to a 2018 study. People may be at a higher risk for HPPD if they or their family have a history of eye floaters, tinnitus (ringing in the ears), or serious concentration issues. There is no officially recognized cure for HPPD. Still, those experiencing it are advised to cease recreational drug use, and pharmaceutical drugs and specific therapies show promise in treating the condition.
Richard speaks to the lasting effects of LSD in a more general sense. “Perhaps all experiences”—not just psychedelics—”[can] change our brains,” he says. “The relation of the brain to consciousness remains a deep philosophical and scientific question. I am aware of no respectable evidence that pure LSD causes physiological damage.”
*This article was independently fact-checked before publication.
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