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Cannabis

Greening Out: What It Is, What to Do, and When It Is a Pattern

Reviewed by the clinical team at South Jersey Recovery Program · Updated

“Greening out” is the informal name for an overwhelming reaction to too much THC. The person goes pale and sweaty. The room spins. The heart pounds. Nausea builds, and many people vomit. Some become convinced they are dying, and that fear makes every physical symptom worse.

We hear about greening out constantly at South Jersey Recovery Program, usually from two kinds of people. The first had a bad night with an edible and wants to know whether it was dangerous. The second has greened out several times, keeps using anyway, and has started to wonder what that says. This article is for both. It explains what is happening in the body, what to do in the moment, when to get medical help, and when a green-out is information rather than an accident.

Most healthy adults get through a green-out with time and supportive care. That is not the same as saying every reaction is safe to manage at home. A child who has ingested cannabis needs medical help right away. So does anyone who cannot be woken, has trouble breathing, has a seizure, has chest pain, or cannot stop vomiting.

What greening out actually is

THC, or delta-9-tetrahydrocannabinol, is the main intoxicating compound in cannabis. It affects coordination, perception, memory, heart rate, blood pressure, nausea, and anxiety. Push the dose past what a particular body can tolerate on a particular day, and those effects stop being recreational and start being overwhelming.

The threshold moves. Tolerance, body size, when you last ate, hydration, sleep, baseline anxiety, and especially alcohol all shift it. This is how someone uses a familiar amount and greens out “for no reason.” The dose did not change. The body’s limit did.

Symptoms

A green-out usually brings several of the following. Smoked or vaped cannabis produces them within minutes. Edibles take an hour or more, which is why people take a second dose and then get hit by both.

  • Nausea and vomiting, often the defining symptom
  • Dizziness, or the sense that the room is spinning, especially on standing
  • Pale, clammy skin and cold sweats
  • A racing heartbeat and a strong awareness of it
  • A drop in blood pressure, with lightheadedness, tunnel vision, and sometimes fainting
  • Anxiety, dread, or panic, sometimes with a feeling that nothing is real
  • Confusion or slowed thinking
  • Shakiness or chills

Why it is happening more often

Cannabis is stronger than it used to be. The National Institute on Drug Abuse reports that the average THC potency of cannabis seized by law enforcement quadrupled between 1995 and 2022, from 3.96% to 16.14%. Dispensary flower and concentrates sold legally in New Jersey are frequently stronger than that. Higher potency narrows the gap between a comfortable dose and an overwhelming one, and a narrow gap gets crossed by accident.

Edibles add a second problem. They are absorbed slowly, they are easy to misjudge, and a gummy looks like candy. Our edibles guide covers why they hit later and harder. Edible cannabis exposures in children under six reported to U.S. poison centers rose from 207 cases in 2017 to 3,054 in 2021, according to a 2023 study in the journal Pediatrics, and about one in five of those children was admitted to a hospital. In a state where dispensaries are on the main road, that risk now lives in a lot of kitchen drawers.

What to do when someone greens out

There is no reversal agent for THC. Time is the treatment, and the job of the person helping is to keep the other person safe and calm while the body does its work.

  1. Get them seated or lying down somewhere quiet. Fainting after standing up too fast is the most common way people get hurt during a green-out. If they are lying down and nauseated, turn them onto their side.
  2. Reassure them, specifically and repeatedly. Anxiety amplifies every symptom on the list. Say what is true: they had cannabis, they are having a difficult reaction, and you are staying with them.
  3. Offer small sips of water. Vomiting and sweating dehydrate. Food is optional, and something bland is fine if they want it.
  4. Cool them down. Fresh air, a fan, or a cool damp cloth on the neck.
  5. Do not add anything. No alcohol to take the edge off, no other substances, and no more cannabis. Nothing sold over the counter reverses THC.
  6. Stay. Smoked reactions often ease within a few hours. Edible reactions run longer. Someone should be present until the person is clearly recovering.

If you are unsure whether what you are seeing needs medical attention, that is what Poison Control is for. Call 1-800-222-1222. It is free, confidential, staffed around the clock by specialists, and they will tell you whether the situation can be managed at home.

When to call 911

Call 911 or go to an emergency department if any of the following occur:

  • The person is unresponsive or cannot be woken
  • Seizure activity
  • Trouble breathing or bluish lips
  • Chest pain, or a racing or irregular heartbeat that is not settling
  • Repeated vomiting that will not stop, or signs of serious dehydration
  • The product may have been counterfeit or contaminated, or other substances were taken with it
  • Severe agitation, paranoia, or any talk of self-harm. For a mental health crisis, call or text 988.

A child who may have ingested cannabis needs a call to Poison Control immediately. If the child collapses, has a seizure, has trouble breathing, or cannot be woken, call 911.

How long it lasts

Smoked or vaped cannabis announces itself within minutes and usually eases within a few hours. Edibles are the opposite problem: slow to start, able to build for hours, and capable of impairing someone for much of a day. Product strength, dose, tolerance, other substances, and individual metabolism all bend the timeline. If symptoms are severe, worsening, or lasting longer than seems reasonable, call Poison Control rather than trusting the clock.

When greening out is a pattern

One miscalculation is a bad night. A pattern is information.

Continuing to use cannabis despite repeated physical or psychological problems is one of the diagnostic signs of cannabis use disorder. So is using more than you intended, which is what a green-out often is. The Centers for Disease Control and Prevention estimates that approximately 3 in 10 people who use cannabis have cannabis use disorder, and the risk is higher for people who started young and people who use frequently.

In our outpatient program, the clients who have greened out repeatedly usually share a history. Daily or near-daily use. Tolerance that keeps climbing, so they reach for stronger products. Anxiety or sleep problems that cannabis was supposed to fix and now makes worse. A few quit attempts that lasted a week. None of that is a character flaw. It is the shape of a treatable condition.

Two other patterns deserve a clinician’s attention. Recurring severe vomiting in a long-term daily user may be cannabinoid hyperemesis syndrome, which is a different problem from a green-out and can become a medical emergency. And a green-out that turns into lasting panic, paranoia, or a feeling of unreality that does not fade with the high is a reason to be evaluated, because cannabis can unmask anxiety and other mental health conditions that were already there. Our guide to weed and panic attacks covers that pattern.

What treatment looks like

Cannabis use disorder does not usually require a hospital or a residential program. It usually requires structured outpatient treatment. There is no FDA-approved medication for it, so the work is done through therapies that have been tested for this condition: cognitive behavioral therapy, motivational enhancement therapy, and contingency management. At South Jersey Recovery Program, that treatment runs through partial care, an intensive outpatient program, and standard outpatient therapy, all in Berlin, NJ, and all while clients keep living at home. Our marijuana addiction treatment page explains how we match the level of care to the person.

If cannabis has become hard to moderate, one conversation with an addiction-trained clinician is worth more than another round of trial and error. Call us, or reach New Jersey’s free 24-hour addiction helpline, ReachNJ, at 1-844-732-2465.

At a glance

  • Greening out is an acute overreaction to THC: nausea, dizziness, sweating, a racing heart, anxiety, and sometimes vomiting or fainting.
  • Most healthy adults recover with supportive care. Severe symptoms, a possible child exposure, mixed substances, or an unknown product require expert guidance.
  • Care is supportive: a calm place, reassurance, sips of water, side-lying if vomiting, and no additional substances.
  • Call 911 for unresponsiveness, seizures, breathing trouble, chest pain, or vomiting that will not stop. Call Poison Control at 1-800-222-1222 for anything you are unsure about.
  • Repeated green-outs, or heavy use that continues despite them, are a reason to talk to a professional.

Sources

This article is for general education and is not a substitute for individualized medical advice. If you are in crisis, call or text 988, or dial 911 in an emergency.

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