According to the Centers for Disease Control and Prevention, a fatal overdose of marijuana is very unlikely. However, marijuana can also have harmful side effects, especially if taken in high doses.   Doctors published a 2019 letter in the New England Journal of Medicine detailing the story of a marijuana overdose. As he was undergoing brain tumor treatment, the patient, a 52 year old man, had been using marijuana to increase his appetite. The patient experienced confusion, restlessness, speech problems, as well as confusion, for two days before he sought emergency care.   The man had consumed approximately 330 mg of THC, which is the active ingredient in marijuana. The usual dose is 10 mg. This man had consumed more than 30 times the usual dose. This could lead to a fatal overdose with many drugs. Although it wasn't fatal in this case, the man experienced intense confusion which subsided soon after he was admitted to hospital.   Levine states that marijuana overdose can lead to a variety of dangerous symptoms. These symptoms can include:   Panic attacks and anxiety Psychotic thinking Hallucinations High blood pressure and rapid heart beat Questions of coordination Indirectly, these can lead to death. For example, a person may drive under the influence of mairjuana and fall because they are confused.