Is it possible to “overdose” or have a “bad reaction” to marijuana?

A fatal overdose is unlikely, but that doesn’t mean marijuana is harmless. The signs of using too much marijuana are similar to the typical effects of using marijuana but more severe. These signs may include extreme confusion, anxiety, paranoia, panic, fast heart rate, delusions or hallucinations, increased blood pressure, and severe nausea or vomiting. In some cases, these reactions can lead to unintentional injury such as a motor vehicle crash, fall, or poisoning.