Twelve Health Risks from Smoking Marijuana

Big Tobacco? Get ready for Big Marijuana! Please don’t smoke it. The health risks are too great.

You are no longer smoking “Woodstock marijuana” of 1969. This is now “turbo marijuana.”

In some products, its potency can be like taking twelve shots of vodka per day.

The higher the potency, the greater risk of addiction; and then you buy more of Big Marijuana’s product.

Presently, we’re in crisis mode or about to be in one. The number of marijuana users among teens is increasing. In 2013, the Substance Abuse and Mental Health Services Administration reports:

[M]arijuana use rose to 7.5% of users aged 12 or older in 2013. This is up from 6.2% of users in 2002.

Additional NSDUH findings on marijuana include:

• 19.8 million (7.5%) people were current (past month) users of marijuana in 2013, making it the most used illicit drug.
• Marijuana use was most prevalent among people age 18 to 25 (with 19.1% using it in the past month).
• 7.1% of people aged 12 to 17 reported using marijuana.
• A higher percentage of males (9.7%) used marijuana in the past month than females (5.6%).

These numbers will not decrease when more states legalize the drug, because of the widespread availability and the barriers of the law are lifted.

I come at this as a college teacher in the humanities, not the sciences. In discussing the topic with students, time and again they tell me marijuana is harmless and nonaddictive. Remarkably, some tell me it improves their already-healthy bodies. They get this odd information from weed-promoting websites. So I post this article to provide links to scientific studies and conclusions.

This is what the science says about the risks.

1. Risk of “turbo” marijuana

To set the stage for the other risks, in the marijuana of today the THC levels, which gives the “high,” are extremely potent, compared to thirty or forty years ago. Former Senior Advisor in President Obama’s drug policy office, Kevin Sabet, Ph.D., describes the increased potency:

At the University of Mississippi, a potency-monitoring project has been underway for the past few decades, measuring the concentration of THC in thousands of marijuana samples randomly selected from law-enforcement seizures. Since 1983, when THC concentrations averaged below 4 percent, potency has intensified until it now exceeds an average of 10 percent. Many marijuana samples are in the 10-20 percent range. Some marijuana samples show THC concentrations exceeding 30 percent. (Sabet 34-35)

Then Sabet draws a comparison with alcohol: “If we were talking about alcohol, this increase in intoxication potential would be like going from drinking a “lite” beer a day to consuming a dozen shots of vodka” (35).

We are far from “Woodstock marijuana” of 1969.

The stronger the dosage, the more likely there is addiction, and the more money flows to the marijuana industry. Big Tobacco? Now we have Big Marijuana.

But please don’t believe that smoking a milder plant eliminates health risks.

2. Risk of addiction

Not everyone who smokes marijuana will get addicted, but does a reasonable person want to risk it? A team of medical professionals published their study of cannabis in the New England Journal of Medicine (NEJM), concluding: “Despite some contentious discussions regarding the addictiveness of marijuana, the evidence clearly indicates that long-term marijuana use can lead to addiction.”

3. Risk of cardiovascular (heart) disease and strokes

Summarizing a French study, the LA Times reports:

“There is now compelling evidence on the growing risk of marijuana-associated adverse cardiovascular effects, especially in young people,” said Emilie Jouanjus, lead author of the French study, which was also published in the Journal of the American Heart Assn. That evidence, Jouanjus added, should prompt cardiologists to consider marijuana use a potential cause of cardiovascular disease in patients they see.

Also go here.

4. Risk of going to harder drugs

Marijuana could be a gateway drug. The authors of the marijuana study reported in the NEJM say: “Epidemiologic and preclinical data suggest that the use of marijuana in adolescence could influence multiple addictive behaviors in adulthood.”

William J. Bennett and Robert A. White insightfully observe that not everyone who smokes marijuana will go on to a harder drug, but nearly everyone on a harder drug began with marijuana (114).

5. Risk of lung damage

The American Lung Association reports:

Smoking marijuana clearly damages the human lung. Research shows that smoking marijuana causes chronic bronchitis and marijuana smoke has been shown to injure the cell linings of the large airways, which could explain why smoking marijuana leads to symptoms such as chronic cough, phlegm production, wheeze and acute bronchitis.

6. Risk of brain chemistry damage

A study by the Society of Nuclear Medicine  and reported in Sciencedaily concludes:

Definitive proof of an adverse effect of chronic marijuana use revealed at SNM’s 58th Annual Meeting could lead to potential drug treatments and aid other research involved in cannabinoid receptors, a neurotransmission system receiving a lot of attention. Scientists used molecular imaging to visualize changes in the brains of heavy marijuana smokers versus non-smokers and found that abuse of the drug led to a decreased number of cannabinoid CB1 receptors, which are involved in not just pleasure, appetite and pain tolerance but a host of other psychological and physiological functions of the body.

7. Risk of brain structure damage and memory loss

A study conducted by the Northwestern University Feinberg School of Medicine and reported in the Bulletin of Schizophrenia and a Northwestern news release concludes:

“The study links the chronic use of marijuana to these concerning brain abnormalities that appear to last for at least a few years after people stop using it,” said lead study author Matthew Smith, an assistant research professor in psychiatry and behavioral sciences at Northwestern University Feinberg School of Medicine. “With the movement to decriminalize marijuana, we need more research to understand its effect on the brain.”

It should also be noted in that excerpt that the authors of the study urge caution about decriminalizing marijuana.

8. Risk of schizophrenia and other psychoses

The same study by the Northwestern University Feinberg School of Medicine observes:

Chronic use of marijuana may contribute to changes in brain structure that are associated with having schizophrenia, the Northwestern research shows. Of the 15 marijuana smokers who had schizophrenia in the study, 90 percent started heavily using the drug before they developed the mental disorder. Marijuana abuse has been linked to developing schizophrenia in prior research.

In a news release, NATAP  publishes an Australian study, “Cannabis Use and Early Onset of Psychosis”:

We found that the use of cannabis and other illicit substances was associated with an earlier age at onset of psychotic disorders. In contrast, alcohol use alone did not appear to be significantly associated with a younger age at onset of psychosis. With regard to our a priori hypothesis, we found that a higher proportion of cannabis users in the substance-using groups significantly contributed to the heterogeneity in the effect size, indicating an earlier mean age at onset of psychosis in samples with more cannabis users.

9. Risk of an IQ drop among adolescents

The lead investigator Madeline H. Meier of the IQ study says:

“Our results suggest that adolescents are particularly vulnerable to develop cognitive impairment from cannabis and that the drug, far from being harmless, as many teens and even adults are coming to believe, can have severe neurotoxic effects on the adolescent brain.”

This study was attacked by Norwegian Dr. Rogeberg for not considering other factors, like socioeconomic class. So a year later scientists of the IQ study respond to Dr. Rogeberg, saying that socioeconomic factors alone don’t explain the drop because they restricted their study to the middle class:

Dr. Rogeberg’s ideas are interesting, but his challenge is based on simulations. We used actual data on 1,037 people to carry out the analyses he suggested. His ideas are not supported by our data. … Nevertheless, to address his claim, we restricted our analysis to individuals in middle-class families (whose primary breadwinner had occupations such as building inspector, plumber, or aircraft mechanic), and we excluded low-SES families as well as high-SES families (whose breadwinners had professional occupations such as dentist). By restricting our analysis to only include children from middle-class homes, our findings of IQ decline in adolescent-onset cannabis users remain unaltered, thereby suggesting that the decline in IQ cannot be attributed to socioeconomic factors alone.

Read what Dr. Nora Volkow of the National Institute of Drug Abuse has to say about the success of the study, here.

10. Risk of poor school performance

Though teens are the ones considered here, it is difficult to believe regular adult users won’t lower job performance as the years go on.

The same team of medical professionals who published their study of cannabis in the New England Journal of Medicine writes that poor performance and dropping out has multiple factors, but marijuana is a major one:

… [E]arly marijuana use is associated with impaired school performance and an increased risk of dropping out of school, although reports of shared environmental factors that influence the risks of using cannabis at a young age and dropping out of school suggest that the relationship may be more complex. Heavy marijuana use has been linked to lower income, greater need for socioeconomic assistance, unemployment, criminal behavior, and lower satisfaction with life.

11. Risk of a car crash

Marijuana slows the motor or movement skills in users, so not surprisingly there is an increase in the incidents of car crashes. USA Today reports the findings:

As more states are poised to legalize medicinal marijuana, it’s looking like dope is playing a larger role as a cause of fatal traffic accidents.

Columbia University researchers performing a toxicology examination of nearly 24,000 driving fatalities concluded that marijuana contributed to 12% of traffic deaths in 2010, tripled from a decade earlier.

NHTSA studies have found drugged driving to be particularly prevalent among younger motorists. One in eight high school seniors responding to a 2010 survey admitted to driving after smoking marijuana. Nearly a quarter of drivers killed in drug-related car crashes were younger than 25. Likewise, nearly half of fatally injured drivers who tested positive for marijuana were younger than 25.

Since de facto legalizing marijuana through “medical” marijuana, Colorado has seen an increase in motorist fatalities:

Colorado has seen a spike in driving fatalities in which marijuana alone was involved, according to The trend started in 2009 — the year medical marijuana dispensaries were effectively legalized at the state level.

12. Risks of smoking or eating marijuana for “medical” reasons

–“We will use [medical marijuana] as a red herring to give marijuana a good name”–

So said Keith Stroup, in 1979, head of the National Organization for the Reform of Marijuana Laws (NORML) (qtd. in Sabet 55)

Marijuana advocates have used legalizing medical marijuana to get the public to accept legalizing its recreational use. They have been dishonestly appealing to people’s natural compassion for human suffering.

Yes, it is true that a smoked or eaten substance that tweaks the brain can provide relief from various symptoms,  but multiple health agencies report that smoking it for medicinal purposes is unsafe, while alternative treatments are available. The FDA writes in 2013:

… [T]here is currently sound evidence that smoked marijuana is harmful. A past evaluation by several Department of Health and Human Services (HHS) agencies, including the Food and Drug Administration (FDA), Substance Abuse and Mental Health Services Administration (SAMHSA) and National Institute for Drug Abuse (NIDA), concluded that no sound scientific studies supported medical use of marijuana for treatment in the United States, and no animal or human data supported the safety or efficacy of marijuana for general medical use. There are alternative FDA-approved medications in existence for treatment of many of the proposed uses of smoked marijuana. (updated in 2014)

Sabet adds this about smoking and eating marijuana: “In no other realm of medicine is ‘smoking’ considered to be therapeutic. In fact, smoking any drug is a problem because there is no way to standardize a dose. Other ‘delivery systems,’ for instance, edibles and beverages, have similar problems. That is why no modern medicine is smoked and the FDA has never approved smoking as a safe delivery system” (64).

Should we chew on the opium plant to get morphine or on willow bark to get our daily dose of aspirin? Whatever medicine exists in these plants needs to be extracted, and then the doses can be controlled (Sabet 57).

Further, some believe that marijuana can inhibit tumor growth. There is some evidence for it.  But this benefit comes from plant extracts (no. 5). So people shouldn’t expect to smoke or eat their way to a cancer cure.

As for helping glaucoma, the American Glaucoma Society concludes:

… Although marijuana can lower the intraocular pressure (IOP), its side effects and short duration of action, coupled with a lack of evidence that its use alters the course of glaucoma, preclude recommending this drug in any form for the treatment of glaucoma at the present time.

Smoking and eating marijuana has too many risks. Other forms of medical marijuana, like Marinol, are FDA approved, safer, and effective.

Skewed science?

Sometimes Big Marijuana advocates for legalization contest these studies because they are supposedly sponsored by big corporations or skewed by political pressure put on government health and law enforcement institutes.

However, the advocates are also motivated by politics and money. The more users they get, the more money flows their way. It’s a commercial enterprise.

One gets the feeling that if these studies supported weed legalization and general health, the Big Marijuana advocates would celebrate the studies, not doubt them.

So can we break the deadlock?

Common sense combined with science is just about all we got. Inhaling smoke or eating baked-in plants of a chemical-laden and brain-tweaking drug defies both common sense and the science. Marijuana is not healthy; it is unhealthy.

Do hyper-skeptics about the science when it doesn’t suit them want to risk their health and the health of other users when they promote marijuana on their websites and other media outlets?

To help them answer that question, a bullet list of the side-effects follows.


Here is a summary of the risks to health and of altered behavior and diminished achievement.

The American Academy of Child and Adolescent Psychiatry issued this statement:

Use of marijuana can lead to:
• School difficulties
• Problems with memory and concentration
• Increased aggression
• Car accidents
• Use of other drugs or alcohol
• Risky sexual behaviors
• Increased risk of suicide
• Increased risk of psychosis
Long-term use of marijuana can lead to:
• The same breathing problems as smoking cigarettes (coughing, wheezing, trouble with physical activity, and lung cancer)
• Decreased motivation or interest
• Lower intelligence
• Mental health problems, such as depression, anxiety, anger, moodiness, and
• Psychosis
• Decreased or lack of response to mental health medication
• Increased risk of side effects from mental health medication

Sabet also summarizes the risks in terms of emergency room admissions from using THC-intensified marijuana: “The nationwide total went from an estimated 16,521 emergency room visits in the United States related to marijuana use in 1991, to exceeding 374,000 emergency room admission in 2008—a nearly twenty-five fold increase in just seventeen years” (35-36).


Most importantly, behind these policy statements and scientific findings and convenient hyper-skepticism about motives and science are human lives.

Think before you take up this drug. Your quality of life will be negatively affected. If you currently take it, be persuadable and stop.

Given these health risks, states must no longer vote to legalize recreational marijuana.

And states that have legalized recreational use must reverse their unwise decision.


Five Myths about Marijuana and You

Five Myths about Marijuana and Society

Twelve Health Risks from Smoking Marijuana

Don’t Legalize Recreational or Medical Marijuana

Offsite: Heather MacDonald has written a piece about decriminalization in the City Journal: The Decriminalization Delusion.

In MLA format, please cite this source as follows:

Arlandson, James. “Twelve Health Risks from Smoking Pot.” Drjimsebt. 14 May. 2020 Web. [date you accessed it]

In APA use, use this format:

Arlandson J. (2020, May 14). Twelve health risks from smoking pot. djimsebt. com. Retrieved from [now paste the URL]

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