Cannabis overdose means taking more THC than the body can process. The result is a group of symptoms that lasts hours. Death from cannabis alone is not confirmed in adults. Severe cases still land in emergency rooms.
Common signs: heart rate above 100 beats per minute, dry mouth, red eyes, trouble walking, slow speech, nausea, vomiting, anxiety, panic, paranoia. Symptoms start 30 to 60 minutes after smoking or vaping and 1 to 3 hours after eating an edible.
Symptoms by dose
Low to moderate
- Heart rate above 100 beats per minute
- Dizziness when standing
- Short term memory loss
- Nausea, one or two vomits
High dose
- Vomiting that does not stop
- Panic attack, sense of doom
- Hallucinations, disorientation
- Chest pain, muscle twitching
Emergency
- Seizure
- Breathing slower than 10 breaths per minute
- Unconsciousness, no response to voice
- Psychosis that does not stop
Timing
Edibles peak at 2 to 4 hours and last 6 to 12 hours. Inhaled THC peaks in 10 to 30 minutes and lasts 2 to 4 hours. People take a second dose before the first one takes effect. This is the most common cause of a bad edible reaction.
What to do
- Stop using cannabis.
- Sit up or lie on the side. Vomiting on the back blocks the airway.
- Drink water in small sips.
- Stay with the person. Do not leave them alone.
- Call Poison Control at 1-800-222-1222. The line is open 24 hours.
Do not give more cannabis to balance the effect. Do not give food or drink to a person who cannot swallow.
When to call 911
Call 911 for seizure, chest pain, breathing under 10 breaths per minute, blue lips, or a person who does not wake to a loud voice.
Cannabis hyperemesis syndrome
Some long term users get CHS. Signs: repeated vomiting, stomach pain, and relief from hot showers or baths. Episodes last 24 to 48 hours. The only known cure is stopping cannabis. Hot bathing raises burn and dehydration risk.
Who is at higher risk
- Children under 6. Edibles look like candy and gummies. US poison centers logged 3,054 edible exposures in children under 6 in 2021.
- First time users
- People on sedatives, opioids, or antidepressants
- People with heart conditions or prior psychosis
What is not supported
US federal agencies record no confirmed death from cannabis alone in a healthy adult. That does not make high doses safe. Synthetic cannabinoids and cannabis mixed with other drugs cause most severe outcomes in reported cases.