The main symptoms of a cannabis overdose are intense anxiety, panic, paranoia, a fast or pounding heartbeat, nausea, vomiting, dizziness, confusion, and extreme drowsiness. A cannabis overdose is rarely fatal on its own, but it can feel frightening, last for hours, and may need medical care, especially when alcohol or other drugs are involved.
What a cannabis overdose means
Cannabis overdose, sometimes called "greening out," describes the effects of taking in more THC than your body can handle comfortably. THC is the compound in cannabis that causes intoxication. There is no confirmed lethal dose of THC in humans, so death from cannabis alone has not been documented. That does not make a high dose harmless. Very high THC amounts can cause severe distress, and the risk rises with edibles, concentrates, and synthetic cannabinoids.
Symptoms of a Cannabis High: Effects, Timing, and What Helps
Common symptoms of a cannabis overdose
Symptoms of a cannabis overdose usually start within minutes after smoking or vaping, or within 30 minutes to 2 hours after eating an edible. They can include:
- Severe anxiety or panic
- Paranoia or suspicious thinking
- Rapid or pounding heartbeat
- Nausea and vomiting
- Dizziness, lightheadedness, or fainting
- Confusion, disorientation, or trouble speaking
- Dry mouth and red eyes
- Shaky hands, poor coordination, or trouble walking
- Extreme sleepiness or trouble staying awake
- Hallucinations, delusions, or feeling detached from reality
- Chills, sweating, or feeling hot and cold
- Headache
These effects vary by person, dose, product potency, and tolerance. A person who is new to cannabis or who has not used it in a long time may feel strong effects from a small amount.
Edibles vs. inhaled cannabis
Edibles are a common cause of unpleasant cannabis reactions. The liver converts THC into a stronger form, and the effects take longer to appear. People who eat more because they do not feel anything right away can end up with a dose that is far too high. Inhaled cannabis hits faster, so the peak is quicker, but the overall experience usually passes sooner.
When a cannabis overdose becomes an emergency
Call 911 or seek emergency care if a person has:
- Chest pain or a heartbeat that feels out of control
- Vomiting that will not stop
- Seizures
- Slow, weak, or irregular breathing
- Unresponsiveness or trouble waking up
- Severe confusion or agitation
- Thoughts of self-harm
- Symptoms after mixing cannabis with alcohol, opioids, benzodiazepines, or other drugs
Children who swallow edibles or cannabis products need medical attention right away, even if they seem fine at first.
What to do if you or someone else took too much
- Stay with the person and keep the room calm and quiet.
- Offer water if the person is awake and can swallow.
- Do not induce vomiting unless a medical professional tells you to.
- Keep the person sitting or lying on their side if they feel sick.
- Do not let them drive or operate anything.
- Call Poison Control at 1-800-222-1222 for guidance, or 911 for severe symptoms.
Most cases improve with time, rest, and fluids. The unpleasant feelings can last several hours after an edible, and a smaller number of people feel off for a day or more.
How CBD fits into the picture
CBD does not cause the same intoxicating high as THC, and a CBD overdose is not linked to the emergency effects described above. Some people still report drowsiness, upset stomach, or loose stools at high CBD doses. CBD can also interact with certain medications, including blood thinners and some seizure drugs, so it is worth talking with a clinician before adding it to a routine. Choosing lab-tested CBD products helps you know what is in each dose and avoid unexpected THC content.
Frequently asked questions
Can you die from a cannabis overdose?
No confirmed lethal overdose from cannabis alone has been reported in humans. The greater danger comes from accidents, panic, mixing substances, or an underlying heart condition.
Can you overdose on CBD?
CBD is not intoxicating, and serious overdose is not expected. Large amounts may cause sleepiness, nausea, or diarrhea, and CBD can raise the levels of some prescription drugs.
How long do cannabis overdose symptoms last?
Smoked cannabis effects often peak within 10 to 30 minutes and fade over 1 to 3 hours. Edible effects can last 6 to 8 hours or longer.