Greening out is an informal term for an uncomfortable or overwhelming reaction after consuming cannabis, often after consuming more THC than a person can tolerate. Symptoms may include nausea, dizziness, anxiety, panic, paranoia, and confusion.[3,4,5
Emergency warning: Call 911 immediately if a teen has trouble breathing, cannot be awakened, has a seizure, collapses, has chest pain, or becomes an immediate danger to themselves or someone else. Do not wait for the expected effects of cannabis to wear off.
THC, or tetrahydrocannabinol, is the main psychoactive compound in cannabis. It can affect perception, memory, coordination, judgment, and mood. [1,2] When someone consumes more THC than they tolerate, the experience can become frightening or physically unpleasant.
A teenager who is greening out may feel dizzy, nauseated, sweaty, anxious, confused, or unusually aware of their heartbeat. Some teens may also experience panic, paranoia, or hallucinations.[1,3,4,8]
Greening out is not the same as a fatal overdose caused by opioids or other drugs that can suppress breathing. A fatal overdose caused solely by cannabis is considered unlikely, according to the CDC.[1] However, cannabis overconsumption can still cause severe poisoning, injury, dangerous behavioral changes, and other medical complications.[1,2]
The term does not tell how serious a reaction is. [3,4,5] A teen who appears to be having a typical uncomfortable cannabis reaction may instead have taken another substance, consumed a highly concentrated product, or developed a medical emergency.[1,2]
That is why parents should pay attention to the actual symptoms rather than assuming every reaction is simply “being too high.”
What Causes a Teenager to Green Out?
Greening out generally occurs when the amount of THC consumed overwhelms a person’s tolerance. The reaction can happen after smoking, vaping, eating cannabis-infused foods, or using other THC products.[1,2,3]
Several factors can increase the likelihood of an overwhelming reaction.
High-THC Cannabis Products
Cannabis products vary in THC concentration. A teenager who consumes a high-potency product may experience stronger effects than expected, particularly if they have little experience with cannabis.[1,2,3]
Concentrates, some vape products, and high-THC edibles can make it difficult to judge how much THC has been consumed, especially when the product’s THC content is unclear. [1,2]
Edibles and Delayed Effects
Edibles are a common reason people consume more THC than intended.
After eating a cannabis-infused product, intoxicating effects may take 30 minutes to 2 hours to begin. A teenager may assume the edible is not working and consume more before the first dose has taken effect. [1,6]
Taking more before the first dose has taken effect can increase the risk of an unexpectedly intense or prolonged reaction. Delayed onset and prolonged effects can increase the risk of consuming more THC than intended. [1,6]
Low or Reduced Tolerance
A teen who rarely uses cannabis may react strongly to an amount that another person tolerates more easily.[1,2,6]
Tolerance also varies between individuals and may change after a period of not using cannabis. However, body size alone cannot reliably predict how someone will respond to THC.[1,2]
Mixing Cannabis With Other Substances
Alcohol, prescription medications, and other drugs can complicate a cannabis reaction.
When several substances are involved, it may be difficult to determine what is causing the symptoms or how serious the situation is. Combining cannabis with alcohol, sedating medications, or other drugs can increase impairment and make the reaction harder to assess. [1,2]
What Are the Symptoms of Greening Out in Teens?
Greening out can cause both physical and psychological symptoms. The exact experience varies depending on the amount of THC, the product used, the person’s tolerance, and whether other substances were involved.[1,2,3,4]
Physical Symptoms
A teen who is greening out may experience:
- Nausea or vomiting
- Dizziness or lightheadedness
- Sweating or chills
- A racing or pounding heart
- Changes in heart rate or blood pressure
- Weakness or shakiness
- Poor coordination or unsteady movement
- Dry mouth
- Feeling faint
- Changes in alertness
These symptoms can occur during acute cannabis intoxication or cannabis poisoning, although they may also have other causes.
Some teenagers may feel as though the room is spinning or may struggle to stand or walk normally. Others may become unusually tired or have difficulty following a conversation.
Psychological Symptoms
The mental effects can be particularly distressing for teenagers.
Common psychological symptoms may include:
- Anxiety or intense fear
- Panic
- Paranoia
- Confusion
- Difficulty thinking clearly
- Difficulty concentrating
- Altered perception
More serious symptoms may include:
- Hallucinations
- Delusions
- Severe agitation
- Major changes in awareness or behavior
The CDC lists extreme confusion, anxiety, paranoia, panic, delusions, and hallucinations among possible signs of using too much cannabis.
A teen may believe something terrible is happening, feel that they are losing control, or become frightened by physical sensations such as a fast heartbeat. [1,2]
Parents should not dismiss these symptoms as attention-seeking or assume the teen is exaggerating. The experience can be genuinely frightening, even when the reaction is expected to improve.
How Long Does Greening Out in Teens Last?
There is no single, guaranteed duration for greening out. Symptoms may improve within a few hours, but the timeline depends on the cannabis product, amount consumed, route of administration, individual factors, and whether other substances were involved. [1,2,3,4]
Some teens may begin feeling better as the THC effects wear off, while others may continue to experience anxiety, dizziness, nausea, confusion, sleepiness, or a racing heartbeat for several hours. Even after the strongest effects have passed, tiredness, poor concentration, and impaired judgment may continue for longer.
The type of cannabis product also matters. Products containing highly concentrated THC may cause more intense or prolonged symptoms. Edibles can last considerably longer than smoked or vaped cannabis because the body processes them differently. Taking additional cannabis before the first dose has fully taken effect may also increase the intensity and duration of symptoms.
If symptoms are severe, worsening, or not improving, do not assume the teen is simply experiencing a typical green-out. Medical assessment may be necessary, especially if the teen has trouble breathing, loses consciousness, has a seizure, develops severe confusion, or cannot be safely monitored.
How Long Does Smoking or Vaping Cannabis Take to Wear Off?
When cannabis is smoked or vaped, effects generally begin within minutes. The strongest effects often occur relatively soon after use, but the overall experience may continue for several hours. The intensity and duration vary depending on the THC concentration, amount consumed, individual tolerance, and whether other substances were involved. [6]
A teen may initially experience dizziness, nausea, anxiety, panic, a racing heartbeat, altered perception, or impaired coordination. As the strongest effects begin to fade, these symptoms may gradually lessen. However, tiredness, anxiety, dizziness, poor concentration, and impaired judgment can continue after the teen no longer feels intensely high. [1,2,6]
The duration of a green-out cannot be predicted precisely from smoking or vaping alone. High-THC products, large amounts, repeated use, low tolerance, dehydration, lack of food, and combining cannabis with alcohol or other drugs may make the experience more difficult or prolonged.
A teen should not drive, ride a bike, operate machinery, swim, or remain alone while impaired. If symptoms are severe, unusual, worsening, or fail to improve, seek medical advice rather than waiting for the effects to disappear.
How Long Do Edibles Take to Wear Off?
Edibles can take longer to begin working and may produce effects that last longer than expected.
The CDC notes that edible cannabis may take 30 minutes to 2 hours to produce intoxicating effects. The duration can vary based on the amount consumed, food intake, medications, alcohol, and other factors. [1,2]
This means a teenager who eats an edible may feel fine initially and then develop intense symptoms later.
Do not use an expected timeline to decide whether a teen is safe. If symptoms are severe, worsening, or unusual, seek medical advice rather than waiting for the expected duration to pass.
Can Greening Out Last Until the Next Day?
Some teens may continue to feel tired, mentally foggy, anxious, or otherwise unwell after the strongest effects have worn off, particularly after consuming a large amount or using an edible.[1,2,6]
However, persistent or worsening symptoms should not automatically be attributed to cannabis. The teenager may have consumed another substance, taken a product with an unknown composition, or developed a medical complication.
If significant symptoms continue, a healthcare professional should evaluate the situation.
What To Do If a Teenager Is Greening Out?
If a teenager is awake, breathing normally, and able to communicate, focus on safety, calm reassurance, and preventing injury. [1,2]
1. Stop Further Cannabis Use
Do not allow the teen to consume more cannabis in an attempt to make the experience better.
If they have taken an edible, do not assume that consuming another substance will cancel out the THC.
2. Move Them to a Calm, Safe Environment
Help the teen sit or lie down in a quiet, familiar place.
Reduce loud music, bright lights, and unnecessary stimulation. Keep them away from stairs, swimming pools, traffic, or other situations where dizziness or impaired coordination could cause injury.[1,2,4]
3. Stay With Them
A calm, sober adult should remain nearby. Speak in a reassuring voice and use simple statements.
Avoid arguing with the teen about what they are feeling or making jokes about their reaction.
4. Offer Small Sips of Water if Appropriate
If the teen is fully alert, able to swallow normally, and not vomiting, small sips of water may be offered for comfort. Do not force fluids or food.
5. Do Not Give Alcohol or Other Drugs
Do not give alcohol, more cannabis, sedating medication, or another drug to try to counteract the effects unless a healthcare professional specifically instructs to do so. Combining substances can worsen impairment and complicate medical assessment. [1,2]
6. Contact Poison Control or a Healthcare Professional
If unsure what the teen consumed, how much they took, or whether the symptoms are serious, contact Poison Control or seek medical advice.
In the United States, Poison Control can be reached at 1-800-222-1222 or through PoisonHelp.org.[11] Call 911 instead when the person has a medical emergency.
When Is Greening Out an Emergency?
Some cannabis reactions require immediate emergency medical care.[1,2]
Call 911 immediately if a teenager:
- Has trouble breathing.
- Cannot be awakened or is unusually unresponsive.
- Experiences a seizure.
- Collapses or loses consciousness.
- Has chest pain.
- Develops severe confusion or dangerous behavior.
- Becomes an immediate danger to themselves or another person.
The CDC specifically recommends emergency care when someone who has used cannabis stops breathing, collapses, or has a seizure. Severe reactions involving confusion, hallucinations, chest pain, a concerning or persistent racing heartbeat, or major changes in alertness require urgent medical evaluation.[1,2,6]
Other Reasons to Seek Prompt Medical Assessment
Even if the teen is conscious and breathing normally, seek medical guidance when they have:
- Repeated or severe vomiting.
- Symptoms that are getting worse instead of improving.
- Severe agitation or hallucinations.
- A very fast or irregular heartbeat that is concerning or persistent.
- A suspected mixture of cannabis with alcohol or other drugs.
- An unknown product or possible exposure to another substance.
- Symptoms that remain significant beyond the expected intoxication period.
Parents do not need to determine the exact diagnosis before seeking help.
Greening Out vs. Cannabis Use Disorder
A single green-out does not automatically mean a teenager has an addiction. [2,4]
However, repeated episodes may indicate that cannabis use is becoming difficult to control or that the teen is continuing to use despite harmful consequences.
Parents should pay attention if a teenager:
- Repeatedly consumes more cannabis than intended.
- Continues using after severe anxiety, vomiting, or panic.
- Has difficulty reducing or stopping cannabis use.
- Spends significant time obtaining or using cannabis.
- Experiences problems at school or home related to cannabis.
- Uses cannabis to cope with anxiety, depression, stress, or sleep problems.
- Continues using despite worsening mental health or physical symptoms.
Cannabis use disorder involves a problematic pattern of cannabis use that causes clinically significant impairment or distress. A professional assessment is needed to determine whether a teen meets the criteria.[2]
Repeated episodes, difficulty stopping cannabis use, or continued use despite harmful consequences should be discussed with a qualified healthcare or behavioral health professional.[5,9]
The important distinction is between one unpleasant reaction and a recurring pattern of substance use.
What Happens at the Hospital After a Teen Greens Out?
Treatment depends on the symptoms and the severity of the reaction.
There is no single antidote that reverses ordinary THC intoxication. Medical care generally focuses on assessing the person, monitoring vital signs, managing symptoms, and treating complications if they develop. [1,2]
A healthcare professional may assess:
- Heart rate and blood pressure.
- Breathing and oxygen levels.
- Mental status and level of consciousness.
- Whether other substances were consumed.
- Whether the teen has an underlying medical condition.
- Whether the symptoms suggest another medical emergency.
The CDC notes that severe cannabis poisoning can require emergency department care or hospitalization, particularly in children who accidentally consume THC products.[1]
If the teenager has repeated episodes or difficulty stopping cannabis use, the next step may involve a behavioral health assessment after the immediate medical concerns have been addressed. [2]
Can Greening Out Cause Long-Term Problems?
A typical, uncomplicated episode of cannabis intoxication generally improves as the effects wear off. However, a severe reaction can create immediate risks, including falls, accidents, dangerous behavior, or medical complications.[1,2]
The CDC warns that consuming too much cannabis can lead to unintentional injuries and poisoning.
It is also important not to assume that every ongoing symptom is caused by cannabis alone.
If a teenager continues to experience hallucinations, confusion, severe anxiety, or other significant mental health symptoms after the acute reaction, they should receive prompt professional evaluation. These symptoms should not automatically be attributed to cannabis alone.[1,2,4,8]
For teens who repeatedly use cannabis or experience problems related to substance use, ongoing behavioral health treatment may be appropriate. [2]
How Clearfork Academy Can Help Teens With Cannabis Use
When greening out becomes a recurring concern, the larger issue may be the teenager’s relationship with cannabis.
A teen may need more than advice about avoiding another bad reaction if cannabis use is affecting school performance, relationships, emotional health, or daily functioning.
Clearfork Academy provides behavioral health treatment for adolescents experiencing substance use and related mental health concerns.
Treatment may help address:
- Repeated or difficult-to-control cannabis use.
- Co-occurring anxiety, depression, or other mental health concerns.
- Family conflict and communication difficulties.
- School or daily functioning problems.
- Difficulty managing stress without substances.
- Relapse prevention and healthier coping strategies.
Clearfork Academy offers different levels of care, including residential treatment, Partial Hospitalization Programs (PHP), Intensive Outpatient Programs (IOP), and Virtual IOP.
The appropriate level of care depends on the teen’s clinical needs, safety, substance-use history, mental health, and available family support.
If a teenager has just experienced a severe cannabis reaction, medical evaluation comes first. Behavioral health treatment can be considered once immediate medical concerns have been addressed and the teen’s ongoing needs have been assessed.
Frequently Asked Questions
Q. What does greening out in teens mean?
Greening out means experiencing an uncomfortable or overwhelming reaction after consuming cannabis, usually more THC than the body can comfortably handle. Symptoms may include nausea, dizziness, anxiety, panic, paranoia, confusion, and a racing heart.
Q. How long does greening out last in teenagers?
The duration varies. Smoking or vaping cannabis generally produces effects sooner, while edibles may take longer to begin working and can last longer. Some symptoms may continue after the strongest effects have passed. Severe or worsening symptoms should be medically evaluated rather than judged by an expected timeline.
Q. Can a teenager die from greening out?
A fatal overdose caused solely by cannabis is considered unlikely, according to the CDC. However, severe cannabis poisoning, injury, and other medical emergencies can occur. Call 911 for breathing problems, seizures, collapse, chest pain, or inability to awaken the teen.
Q. What should parents do if their teen is greening out?
Stay calm, stop further cannabis use, move the teen to a safe environment, and remain with them. If they are alert and swallowing normally, small sips of water may help with comfort. Contact Poison Control or a healthcare professional if concerned. Call 911 for emergency symptoms.
Q. Can greening out cause psychosis in teens?
Cannabis overconsumption can be associated with hallucinations, paranoia, delusions, and other psychotic symptoms. Severe or rapidly worsening changes in behavior or awareness require urgent medical evaluation.
Q. Does greening out mean a teen is addicted to marijuana?
No. A single green-out does not establish cannabis addiction. Repeated use despite harmful consequences, difficulty stopping, cravings, or problems with school, relationships, or mental health may indicate a need for professional assessment.
Q. When should a teen get addiction treatment after greening out?
Treatment may be appropriate when cannabis use is repeated, difficult to control, or affecting the teen’s safety, relationships, school functioning, or mental health. A professional assessment can help determine the appropriate level of care.
Medical Disclaimer: This article is for educational purposes only and does not replace professional medical advice. If a teen experiences severe or worsening symptoms after cannabis use, seek immediate medical care.
References
- Centers for Disease Control and Prevention. Cannabis and Poisoning. February 15, 2024. https://www.cdc.gov/cannabis/health-effects/poisoning.html
- Centers for Disease Control and Prevention. Cannabis Frequently Asked Questions. https://www.cdc.gov/cannabis/faq/
- Centers for Disease Control and Prevention. Cannabis and Teens. February 15, 2024. https://www.cdc.gov/cannabis/health-effects/cannabis-and-teens.html
- Centers for Disease Control and Prevention. Cannabis and Mental Health. February 15, 2024. https://www.cdc.gov/cannabis/health-effects/mental-health.html
- Centers for Disease Control and Prevention. Understanding Your Risk for Cannabis Use Disorder. December 5, 2024. https://www.cdc.gov/cannabis/health-effects/cannabis-use-disorder.html
- Poison Control. Cannabis: Risks and Effects. https://www.poison.org/articles/marijuana
- National Academies of Sciences, Engineering, and Medicine. The Health Effects of Cannabis and Cannabinoids: The Current State of Evidence and Recommendations for Research. National Academies Press, 2017. https://nap.nationalacademies.org/catalog/24625/the-health-effects-of-cannabis-and-cannabinoids-the-current-state
- National Institute on Drug Abuse. Cannabis (Marijuana). https://nida.nih.gov/research-topics/cannabis-marijuana
- Substance Abuse and Mental Health Services Administration. Marijuana and CBD Risks and Resources. https://www.samhsa.gov/substance-use/learn/marijuana-cbd
- American Association of Poison Control Centers. Edible Cannabis. https://www.poisoncenters.org/track/edible-cannabis
- Poison Help. Poison Help: 1-800-222-1222. https://www.poisonhelp.org/
Mike Carter, LCDC
Alumni Relations Manager
Mike grew up on a dairy farm in Parker County, Texas. At the age of 59, he went back to college and graduated 41 years after his first graduation from Weatherford College. God placed on his heart at that time the passion to begin to help others as they walked from addictions, alcoholism, and abuse of substances. He is a Licensed Chemical Dependency Counselor and in the past few years he has worn many hats, from intake and assessment, group counseling, individual and family counseling, intensive outpatient and now he is working with clients, therapist, and families on discharge planning and aftercare. He also coordinates our Alumni Outreach Program.
