Provider News Winter 2015 - Marijuana

Marijuana has numerous adverse health effects

Marijuana is the most common illicit drug used in the United States. After a period of decline, its use has been increasing among young people since 2007. This corresponds with a diminishing perception of the drug’s risks that may be associated with increased public debate over the drug’s legal status. Here is a summary of the physical, mental and social health impacts of marijuana from a public health perspective. Consider using these talking points with your patients and contacts.

Physical health effects

Marijuana’s short-term health effects include slowed reaction time, lack of coordination, altered attention and perception, decreased balance, dizziness, drowsiness, decreased judgment and decision-making, and impulse control issues. This can make driving or other complex tasks dangerous. Some people experience abnormal heart rhythms or increased blood pressure, especially those predisposed to heart disease. Long-term smoking of marijuana increases the risks of lung problems.

Numerous studies show that youth who are heavy users have abnormal changes in their brain structure. Adults who regularly use exhibit decreased brain volume, especially in the hippocampus and amygdala.

Marijuana use is associated with adverse reproductive outcomes, including lower sperm count and decreased fertility. Use in pregnancy increases the risk for stillborn births, and babies born to mothers who used marijuana during pregnancy may have tremors, high pitched cries and decreased responses to stimuli. As a group, children exposed to marijuana in utero exhibit lower school performance and memory abilities than children not exposed. They may also have decreased attentiveness and problem-solving skills.

Mental health effects of marijuana

Marijuana users who ingest high doses may experience acute toxic psychosis, including hallucinations, delusions, and a loss of sense of personal identity. Marijuana can unmask underlying mental illness such as anxiety disorders, personality disorders, schizophrenia or other psychosis, panic attacks, and depression. Early initiation and regular heavy use is also associated with an increased risk of bipolar mood disorder and with psychotic symptoms and disorders in later life.

Social health effects of marijuana

While some argue that using marijuana is a personal choice, there are community impacts when marijuana use is seen as acceptable within a community. The more acceptable and available it is, the more young people are more likely to use it. In Shasta County in 2010-11 (most recent available), 80.9% of 11th graders reported that marijuana is "very easy" or "fairly easy" to obtain. 30% of 9th graders and 45% of 11th graders reported they had tried marijuana at least once.

Users may have trouble sustaining or shifting attention and difficulty registering, organizing and using information, especially complex information. This can lead to decreased employability and lower average incomes among early onset users. Several studies have linked workers’ marijuana use with increased absences, tardiness, accidents, worker’s compensation claims and job turnover.

Marijuana use can reduce motor skills, reaction time and judgment, leading to motor vehicle crashes. Columbia University found marijuana in the blood of 12% of drivers who died in car crashes in 2010, an increase from 4% in 1999. Marijuana is the most prevalent illegal drug detected in impaired drivers, fatally injured drivers and motor vehicle crash victims.

Addiction risk

When quitting marijuana, chronic users may experience withdrawal symptoms that are generally mild compared to withdrawal symptoms from some other drugs of abuse, and typically include irritability, agitation, insomnia, restlessness, anxiety, nausea, and/or cramping. 17% of regular users who started in their early teens become addicted. Half of Shasta County 11th graders who said they used marijuana stated they were 10-14 years old when they started using.

Healthcare providers have enormous influence in our community and can help raise awareness about the health risks of using marijuana. For more information about what you can do, contact Wendy Millis, Community Education Specialist at or 245-6858 or Andrew Deckert, MD, MPH, Health Officer, at or 225-5594.