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Psychedelics & Hallucinogens

What these substances do, how long they last, which combinations are dangerous, how to spot fakes, and how to help someone who is struggling.

A harm reduction reference based on established harm reduction resources and clinical literature. For education, not medical advice. Nothing here encourages use, and there are no dosing instructions on this page, on purpose.

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On this page
The two families Meet the substances Dangerous combos If someone is struggling Fake products Safer use checklist Longer term risks Minnesota law Sources

The two families

Classic psychedelics

These mainly work on the brain's serotonin 2A receptors. They change perception, thought, and mood: visuals, altered sense of time, deep or strange thought loops. Your mindset and surroundings shape the experience enormously.

LSD, psilocybin (shrooms), DMT, mescaline, 2C-B

Dissociatives

These mainly block NMDA receptors instead. They create detachment from your body and surroundings: numbness, floating sensations, confusion, memory gaps. They carry their own distinct physical risks.

Ketamine, DXM, PCP, nitrous oxide

Note on MDMA: molly/ecstasy is an entactogen and stimulant, not a classic psychedelic, even though it is sometimes grouped with hallucinogens. It has its own risk profile, including overheating and serotonin syndrome. Check any combo in the combo checker.

Meet the substances

Duration windows are rough on purpose. Street products vary wildly in strength, and nothing on this page tells you how much to take.

LSD lasts roughly 8 to 12 hours

LSD acid, tabs, blotter, Lucy

Onset 30 to 60 min • Peak 2 to 4 hours • Total 8 to 12 hours
  • Usually taken on small squares of blotter paper. Real LSD is effectively tasteless at blotter strength.
  • Tolerance builds fast. Using two days in a row barely works, and there is cross tolerance with shrooms.
  • Deaths from LSD overdose alone are uncommon. The real dangers are accidents and dangerous behavior while impaired, bad psychological reactions, and mixing with other substances.
  • Fake acid is a serious risk: NBOMe compounds are sometimes sold on blotter as LSD and have caused deaths. See the fake product warning below.
Shrooms (psilocybin) lasts roughly 4 to 6 hours

Psilocybin mushrooms shrooms, magic mushrooms, caps, boomers

Onset around 30 min • Total 4 to 6 hours
  • The body converts psilocybin into psilocin, which produces LSD like effects: visuals, altered time perception, difficulty telling fantasy from reality.
  • Nausea, anxiety, and panic reactions are common, especially with larger amounts. Panic and psychosis are more likely at high doses.
  • Never eat wild mushrooms you picked yourself. Poisonous lookalikes can destroy your liver and kill you. That is a separate danger from the psilocybin itself.
  • In 2024, products marketed as mushroom chocolates ("Diamond Shruumz") sickened at least 180 people across the US. Lab tests found no psilocybin in them at all, just other undisclosed drugs. If it is not from a trusted tested source, assume nothing about what is in it.
DMT and ayahuasca smoked: minutes • brewed: hours

DMT DMT, Dimitri, the spirit molecule

Smoked: onset in seconds • Total under 30 minutes
  • Extremely fast, extremely intense, and short. The intensity catches people off guard even when they expect it.
  • DMT is not active orally on its own. Ayahuasca brews pair it with MAOI containing plants, which makes it orally active and stretches the experience to several hours.
  • The MAOI in ayahuasca is the dangerous part for combos. Mixed with antidepressants, stimulants, or certain foods and meds, it can trigger serotonin toxicity or a hypertensive crisis. Ceremonial settings do not make the pharmacology safer.
Mescaline lasts roughly 8 to 12 hours

Mescaline peyote, San Pedro, buttons

Onset 30 to 60 min, often with nausea • Total 8 to 12 hours
  • The classic long haul psychedelic. Early nausea and vomiting are very common before the visuals arrive.
  • Peyote is a sacrament in the Native American Church, with legal protections for that religious use. That history deserves respect, not tourism.
  • Same family risks as LSD and shrooms: bad psychological reactions, accidents while impaired, dangerous combos.
2C-B lasts roughly 5 to 8 hours

2C-B Nexus, Venus, Bromo

Onset 20 to 90 min • Total 5 to 8 hours
  • A phenethylamine with both psychedelic and stimulant properties. Visuals with a rushing body high, usually a clearer headspace than LSD.
  • Snorting it is notoriously painful and hits much harder and faster. GI distress and nausea are common.
  • "Tusi" or pink powder sold as 2C-B usually is not 2C-B. It is typically a mix of ketamine, MDMA, caffeine, and whatever else. Treat pink powder as an unknown mixture, not as 2C-B.
Ketamine dissociative

Ketamine Special K, K, ket

Effects roughly 1 to 2 hours depending on route
  • A dissociative anesthetic with real medical uses, including anesthesia and treatment resistant depression. Street use is a different story.
  • Chronic heavy use destroys the bladder. Ketamine cystitis means pain, bleeding, constant urgency, and in severe cases permanent bladder shrinkage, kidney damage, or bladder removal. Liver injury and memory problems are also documented with long term heavy use.
  • It is easy to underestimate. Mixing with alcohol or other downers can cause breathing problems and overdose with surprisingly small amounts.
  • Can be habit forming. Tolerance builds and people end up using more often than they planned.
DXM dissociative

DXM dextromethorphan, robo, triple C

Effects roughly 4 to 8 hours at high amounts
  • The cough suppressant in many OTC cold medicines. At high amounts it becomes a full dissociative.
  • Dangerous with antidepressants. DXM plus SSRIs, SNRIs, or MAOIs can trigger serotonin syndrome. Many cold products also contain acetaminophen, which destroys the liver in overdose, or antihistamines that add their own risks.
  • Products sold for this purpose are not dosed for it. There is no safe product lineup here, only riskier and less risky choices.
PCP dissociative

PCP angel dust, sherm, embalming fluid

Effects roughly 4 to 6 hours or longer
  • Unpredictable even for experienced users: numbness and detachment one moment, severe agitation and confusion the next.
  • Severe overdose can cause respiratory depression, coma, seizures, and death. Violent behavior and self injury are documented risks.
  • Sometimes found as a contaminant in other products. If something feels nothing like what you expected, stop and get help rather than taking more.
Nitrous oxide dissociative

Nitrous oxide whippits, balloons, nangs, laughing gas

High lasts minutes
  • The short high is the trap. It feels harmless because it is over fast, so people do dozens in a night.
  • Heavy repeated use inactivates vitamin B12 and damages nerves. Documented outcomes include numbness and tingling in the hands and feet, loss of balance, spinal cord injury, and in some cases permanent disability. England recorded 783 hospital admissions for nitrous use in a single recent year.
  • Breathing it without enough oxygen can kill by asphyxiation. Frostbite from the pressurized canisters and injuries from falling while intoxicated are common ER visits.

Combinations that can hurt or kill

Serotonin syndrome know the signs

Too much serotonin activity at once can cause serotonin syndrome, which is a medical emergency. Watch for this cluster: agitation or confusion, fast heart rate, muscle rigidity or tremors, heavy sweating, fever, and overactive reflexes. Severe cases bring seizures, dangerously high body temperature, and muscle breakdown. If you see this cluster, call 911.

Highest risk combos: psychedelics, MDMA, or DXM taken with SSRIs, SNRIs, MAOIs, or tricyclic antidepressants. Ayahuasca already contains an MAOI, so it is especially dangerous with antidepressants or stimulants. Tramadol and lithium add risk too.

Two things people get wrong:

  • SSRIs blunt the trip. Being on antidepressants often weakens or blocks psychedelic effects. Taking more to compensate raises the danger without reliably raising the high.
  • Do not stop prescribed meds to trip. Antidepressants take weeks to clear, stopping suddenly can cause withdrawal and rebound depression, and the trip is not worth destabilizing your treatment. Talk to your prescriber, not your plug.

Check anything you take, prescribed or not, in the combo checker and the prescription combo guide.

Lithium and psychedelics seizure risk
This one is underappreciated: in a published analysis of experience reports, nearly half of the reports combining lithium with LSD or psilocybin involved seizures, and almost 4 in 10 involved emergency medical treatment. Researchers now consider lithium a contraindication for classic psychedelics.

Lithium is a common bipolar medication, and the interaction is not widely known in party scenes. If you take lithium, treat psychedelics as off the table and talk to your prescriber about any questions. Do not stop lithium abruptly either, withdrawal has its own dangers.

Downers, stimulants, and alcohol
  • Ketamine plus alcohol, GHB, benzos, or opioids: compounded breathing depression. This is how people stop breathing.
  • Psychedelics plus stimulants (cocaine, meth, high dose caffeine): heart strain, overheating, severe anxiety and paranoia.
  • Alcohol plus anything: impairs judgment about redosing, increases nausea and blackouts, and makes every bad outcome more likely.

When in doubt, run the pair through the combo checker before the night starts, not during it.

If someone is struggling

What to do right now
Call 911 immediately for: seizures, trouble breathing or stopped breathing, unconsciousness or cannot be woken, dangerously high body temperature, or violent agitation that puts anyone in danger. Minnesota's Good Samaritan law (604A.05) protects people who call for help during an overdose.
  • Move them somewhere calm, dim, and safe. Reduce noise, lights, and crowds. One calm person stays with them.
  • Reassure, do not argue. "You took something, it will wear off, I am staying with you." Do not try to reason with hallucinations.
  • Do not give them more substances to "calm down," including alcohol or benzos, unless directed by medical professionals.
  • Keep them hydrated with small sips of water if they can swallow safely.
  • If they want to leave, do not let them wander off alone or drive. Stay with them or hand off to someone sober.

Full grounding walkthrough and a trip sitter mode: Bad Trip Guide. Step by step emergency response: Emergency Response.

Fake and contaminated products

"If it is bitter, it is a spitter" fake acid warning

NBOMe compounds (like 25I-NBOMe) are potent synthetic psychedelics sometimes sold on blotter paper as LSD. They have been linked to at least 17 deaths in the US. Real LSD on blotter is effectively tasteless. A bitter or metallic tasting tab is not LSD. Spit it out.

  • NBOMe toxicity looks like: severe agitation, dangerously high heart rate and blood pressure, overheating, seizures, and in bad cases organ failure. It does not feel like a strong acid trip, it feels like a medical emergency. Treat it as one.
  • An Ehrlich reagent test can confirm whether a tab contains an indole like LSD. Fentanyl and xylazine test strips do not detect NBOMe or confirm LSD, they answer a different question.
  • Visually, fake blotter is indistinguishable from real blotter. Taste and testing are your only tools, and testing is the reliable one.

More on spotting fakes: Fake Drugs & Supply Alerts and Test Strips: Check Before You Use.

Safer use checklist

If use is happening anyway, reduce the risk
  • Bring a sober sitter who knows what was taken and stays the whole time. This is the single highest value safety move.
  • Mind set and setting. Your mood and your surroundings shape the experience more than the substance does. Bad headspace plus chaotic venue equals bad night.
  • Test what you have. Reagent tests for blotter, fentanyl and xylazine strips where relevant. See test strips and fake drugs.
  • Do not mix. Especially alcohol, SSRIs, SNRIs, MAOIs, lithium, tramadol, and stimulants. Check combos beforehand in the combo checker.
  • Respect the duration. LSD lasts 8 to 12 hours, shrooms 4 to 6. Do not redose because "nothing is happening yet." Most bad nights start with impatience.
  • Stay cool and hydrated. Dancing plus stimulant properties plus hot venue equals overheating. Water, breaks, shade.
  • Plan the landing. No driving for the full duration plus afterglow. Have a safe place to come down and a ride that does not depend on you being sober enough to arrange one later.
  • Know the law where you are. See below. And know that calling 911 for someone in trouble is protected.

Longer term risks worth knowing

HPPD: when visuals linger rare but real

Hallucinogen Persisting Perception Disorder (HPPD) means visual disturbances that stick around long after the drug wears off: static or "visual snow," trails behind moving objects, halos around lights, intensified colors, geometric patterns. It is recognized in the DSM-5 and is distinct from psychosis: no delusions, just persistent visual noise.

  • It is relatively rare, but it can follow even limited use, not just heavy use. LSD is the most commonly reported trigger.
  • Stress, poor sleep, alcohol, and cannabis can make symptoms worse. For some people it fades over weeks or months. For others it persists longer.
  • If visuals are still hanging around days later and it is distressing, talk to a doctor and be honest about what you took. The MN Resources page has nonjudgmental options.
Mental health history matters

Psychedelics can trigger prolonged psychosis or manic episodes in people with a personal or family history of schizophrenia, schizoaffective disorder, or bipolar I. This is one of the most consistent risk factors in the clinical literature. If serious mental illness runs in your family, that is a strong reason to sit this category out entirely.

They can also amplify existing anxiety and depression in the days after use. The Mental Health & the Scene and Aftercare pages cover the landing.

Minnesota law, briefly

The legal picture

Under Minnesota Statutes 152.02, LSD, mescaline, psilocybin and psilocin, DMT, and 2C-B are Schedule I controlled substances: illegal to possess outside narrow exceptions. Ketamine sits in Schedule III and has legitimate medical uses, which does not make street possession legal.

In 2026 Minnesota lawmakers advanced a bill to create a medical psilocybin therapy pilot program and move psilocybin to Schedule IV. It has not changed the current law. Possession remains illegal statewide as of now.

What does protect you: Minnesota's Good Samaritan law (604A.05) provides protection for people seeking medical help during a drug related emergency. Do not let fear of arrest stop you from calling 911. More detail on the Know Your Rights page.

Sources

Where this page comes from

Every claim on this page traces back to one of these. If any of this conflicts with what a medical professional tells you, trust the professional.

Minnesota's Good Samaritan protections are cited on this page as 604A.05.

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Bad Trip Guide Emergency Response Combo Checker Prescription Combos Test Strips Fake Drugs & Alerts Mental Health & the Scene Aftercare & Recovery MN Resources