Smoking marijuana can lead to more than a euphoric high, and has been linked to long-lasting delusions, mouth swelling and several other surprising effects, according to a new review of research on the recreational use of the drug.
"All recreational users should be aware of potential undesired acute cannabinoid effects," or the effects of being high on pot, study author Dr. Eva Hoch, of the department of addictive behavior and addiction medicine at the University of Heidelberg in Germany, told Live Science. The type and severity of these effects depend on many factors, such as the composition of the cannabis, how often someone uses marijuana, the user's disposition and how much they smoke, Hoch said.
Recreational marijuana use has been legalized in several U.S. states, but researchers are still learning about the effects the drug has on a person's mind and body.
To find out, Hoch and colleagues reviewed 116 previous studies that had focused on recreational use of marijuana, not medical marijuana use. The researchers "were surprised by the variety of potential mental and physical health effects reported in the literature," Hoch said.
For instance, from the review, they identified 12 signs of "acute intoxication" or being high on marijuana, which doctors could use to identify when someone is high. These included feeling anxious or agitated, having a slow reaction time or trouble paying attention, feeling euphoric and disinhibited, having an altered sense of time, having limited judgment abilities, experiencing acoustic, optic or tactile illusions, experiencing feelings of being separate from your body or from reality, exhibiting impaired overall physical and mental performance, experiencing hallucinations or paranoid delusions. [11 Odd Facts About Marijuana]
Although most symptoms of marijuana intoxication typically go away within a few hours of using the drug, people can have delusions that last as long as a week, according to the review.
Recreational marijuana use, they found, has been linked to various mental effects — psychotic symptoms, panic attacks, deficient attention and impaired concentration, the researchers said.
Some consequences of recreational cannabis use on the body include vomiting, inflammation in the mouth, excessively fast heartbeat, arrhythmias, irritation of the respiratory system and chronic bronchitis, according to the review.
Particularly vulnerable to the health effects of marijuana are children and adolescents, people with a history of psychosis, depression, anxiety or other mental disorders, pregnant women, as well as people with pre-existing cardiovascular and respiratory problems, she said.
Addicted to weed
People who use high doses of cannabis frequently over many years, and those who start using in adolescence, may become addicted to the drug, or have withdrawal symptoms when they try to stop using it, Hoch said. These users may also have "cognitive impairment, affective disorders, psychosis, anxiety disorders and physical diseases," such as respiratory and cardiovascular conditions, she said.
Studies have shown that 9 percent of cannabis users, regardless of how often they get high, develop an addiction to the drug, she said. Among daily users, 25 to 50 percent develop an addiction.
In Europe, among people who enter drug treatment programs for using illegal substances, the use of cannabis is the most common reason, the researchers wrote in the review.
"The number of adolescents and adults seeking treatment because of cannabis use disorder is continuously rising in many parts of the world," Hoch said.
The review was published May 5 in the journal Deutsches Ärzteblatt International.