Cannabis poisoning happens when someone consumes enough THC to overwhelm the body’s ability to process it, causing symptoms that range from intense anxiety and a racing heart to, in young children, dangerously slowed breathing. It is not the same as a pleasant high that went slightly too far. Cannabis poisoning involves a level of physical and psychological distress that can require emergency medical care, and ER visits for it nearly doubled in the U.S. between 2016 and 2019, rising from roughly 29,000 to nearly 50,000 annually.
How THC Overwhelms the Body
Your body has its own cannabinoid system, a network of receptors that naturally regulate mood, memory, movement, appetite, and pain. THC mimics the molecules your body already produces for this system, but it floods the receptors far beyond normal levels. The result is erratic signaling across multiple neurotransmitter pathways, including those that control heart rate, coordination, perception, and emotional regulation. This overstimulation is what produces the toxic effects.
The intensity depends on how much THC enters the bloodstream and how quickly. Smoking or vaping delivers THC to the brain within minutes, and peak effects follow shortly after. Edibles are a different story: they take 30 minutes to two hours to produce noticeable effects. That delay is the reason edibles are involved in so many poisoning cases. People eat a dose, feel nothing, eat more, and then absorb far more THC than intended all at once. The intoxication from edibles also lasts significantly longer than from inhaled cannabis.
Symptoms in Adults
The hallmark symptoms of cannabis poisoning are a rapid heart rate, severe anxiety or panic, and impaired coordination. Many people experience dry mouth, red eyes, and an exaggerated appetite, which are familiar effects of normal cannabis use, but at toxic levels these come alongside more distressing symptoms: a feeling that time has slowed to a crawl, social withdrawal, restlessness, and impaired judgment severe enough to lead to injuries.
In more serious cases, poisoning can trigger hallucinations, delusions, or a disturbing sense that the world around you isn’t real. Some people develop a full psychotic episode that can last hours. Intense, overwhelming panic attacks are also common. These psychological effects can be terrifying for the person experiencing them and are one of the main reasons people end up in the emergency department. In 2020, adults aged 26 to 44 accounted for the highest number of cannabis poisoning ER visits and hospitalizations.
Severe, repeated vomiting is another pattern that brings people to the ER, particularly in heavy long-term users. This condition, sometimes called cannabinoid hyperemesis syndrome, involves cycles of nausea and vomiting that can lead to dehydration.
Why Children Are at Much Greater Risk
Cannabis poisoning in children is a genuinely dangerous situation. The most common symptoms in pediatric cases are extreme sleepiness (reported in about 59% of cases), loss of coordination or dizziness (50%), and confusion (34%). But unlike adults, young children are at real risk of respiratory depression, meaning their breathing slows to a point that may require medical intervention. In one study, slowed breathing occurred in 34% of pediatric cases, and 83% of those were children under 10.
Research from the American Academy of Pediatrics has identified a threshold: THC ingestions of 1.7 mg per kilogram of body weight or more can predict severe and prolonged toxicity in children. To put that in practical terms, a standard recreational edible serving contains 10 mg of THC. For a typical three-year-old weighing about 28 pounds, eating just over two of those servings crosses into the danger zone. This is why edibles designed to look like candy, cookies, or gummies pose such a serious risk. A small child can easily eat several pieces before anyone notices.
Younger and smaller children tend to have more severe outcomes. Hospital admission in pediatric cases is strongly associated with lower weight, younger age, and the presence of lethargy or breathing problems. Some children require respiratory support.
How Cannabis Poisoning Is Treated
There is no antidote for THC. Treatment is entirely supportive, meaning the medical team manages symptoms while the drug works its way out of your system. For most adults, this means being placed in a calm, quiet environment with IV fluids and medication for nausea if needed. Sedatives may be given for severe agitation or panic, though these and other medications tried in emergency settings are frequently ineffective at resolving symptoms faster.
For children, treatment is more aggressive. Young or small children who have ingested an unknown amount may receive activated charcoal to limit further absorption, along with IV fluids and close monitoring of their breathing. The goal is to keep the child stable until the THC clears. Most children who receive appropriate care recover completely without lasting effects, but the hours in between can be frightening for families.
Recovery time varies. Inhaled cannabis poisoning typically resolves within a few hours. Edible-related poisoning can last much longer, sometimes 12 hours or more, because the body continues absorbing THC from the digestive tract well after the initial ingestion.
Synthetic Cannabinoids Are Far More Dangerous
Products sometimes sold as “synthetic marijuana” or “spice” are not cannabis at all. They are lab-made chemicals sprayed onto plant material, and they act on the same brain receptors as THC but with much greater intensity. While THC is a partial activator of these receptors, synthetic cannabinoids are full activators. This means they produce effects that are stronger, less predictable, and far more likely to cause life-threatening reactions including seizures, kidney damage, and dangerous heart rhythms. Cannabis poisoning from natural THC is rarely fatal, but synthetic cannabinoid poisoning can be.
Pets and Cannabis Toxicity
Dogs are the most commonly affected pets, and they are significantly more sensitive to THC than humans. A dog that eats an edible or gets into a cannabis stash can develop toxicity rapidly. The most frequently reported signs in dogs are urinary incontinence, disorientation, loss of coordination, lethargy, exaggerated sensitivity to touch and sound, and a slow heart rate. Affected dogs may appear dazed, wobbly, or unresponsive.
Most pets recover fully with appropriate care, and the majority are treated on an outpatient basis. However, veterinarians recommend aggressive treatment for small or young animals because the dose relative to body weight is often unknown. Treatment may include inducing vomiting (if the ingestion was recent), activated charcoal, and IV fluids. The key to a good outcome is telling the veterinarian exactly what the pet consumed. Vets are not interested in judging you; they need accurate information to treat your animal safely.