Cannabis Side Effects: Short-Term and Long-Term

NIDA describes the short-term effects of THC-containing cannabis as including altered time perception and impaired thinking, memory, and body movement, and notes it can make some people irritable or restless. Commonly reported physical effects include increased appetite, an elevated heart rate, and respiratory problems. The CDC adds that cannabis can make the heart beat faster and raise blood pressure immediately after use.

Anxiety, fear, distrust, panic, and hallucinations are more common when a person takes a large amount, uses a high-THC product, or has little experience. For reported effects of specific strains and terpenes, see our effects hub, and remember those are user reports, not guarantees.

The CDC says cannabis, like alcohol, affects skills needed for safe driving: it can slow reaction time and decision-making, impair coordination, and distort perception. Using cannabis and alcohol together can increase impairment. The simplest rule from the CDC: you can choose not to drive after using cannabis. For how long effects typically last, see how long a high lasts.

Edibles take longer to show effects, and NIDA notes people may use more as a result, raising the chance of serious negative effects. The CDC says edibles carry a greater risk of poisoning than smoked cannabis, and that children who eat THC products can become very sick. The CDC advises keeping cannabis products in a locked, childproof container, and lists poison control at 1-800-222-1222 (or 911 in an emergency). Our edible dosing guide covers onset timing.

• Cannabis use disorder. The CDC says about 3 in 10 people who use cannabis have cannabis use disorder, and the risk is higher for people who start young and use more often. Highly concentrated THC products are associated with more severe symptoms.
• Lungs. Smoked cannabis can harm lung tissue. NIDA links long-term smoking with airway inflammation and chronic bronchitis, while noting tobacco co-use makes the effects hard to separate.
• Heart. Some research links long-term use with stroke, heart attack, and arrhythmias, though NIDA says more research is needed to establish a direct connection.
• Cannabinoid hyperemesis syndrome (CHS). NIDA describes CHS as nausea, vomiting, and abdominal pain after long-term, heavy use.
• Mental health. Frequent or heavy use has been linked with problems in learning, memory, and attention, and some evidence links use with earlier onset of psychosis in people at genetic risk. High doses can trigger a temporary psychotic episode in some people.

CBD is not intoxicating, but it is not side-effect free. The FDA lists changes in alertness (most often drowsiness), gastrointestinal upset such as diarrhea and decreased appetite, and mood changes such as irritability and agitation. It also flags risks people may not notice: CBD can cause liver injury and can change how other medicines work. See cannabis drug interactions and what CBD is.