Moderate marijuana use and health effects?

Dear Alice,

Just how dangerous is light to moderate use of marijuana (one joint per week)? I have heard that it is less dangerous than alcohol or tobacco use. Also, its metabolites are stored in fatty tissues, but do they cause any harm?


Dear Reader,

Marijuana (also known as cannabis, weed, pot, grass, herb, bhang, dope, reefer) has become increasingly popular as a drug of choice — but before someone rushes to smoke, eat, or vape it, they may want to learn a bit more about it first. Currently, it’s unclear to what extent light to moderate marijuana use may pose risks to an average person's health. However, research has shown that marijuana contains over 60 chemicals called cannabinoids, one of which — tetrahydrocannabinol (THC)  — is mainly responsible for the mind-altering effects (or “high”) from marijuana. After smoking marijuana, at least 80 THC metabolites are stored in fatty tissue in the body for about three to five days (and for heavy users, this may be longer). While it’s unknown what these metabolites do in the body, the fact that they stay — and build up — raises some concern for long-term health risks of even moderate marijuana use.

The decision to use marijuana varies from person to person, with some people viewing it (and its effects) favorably and others viewing it negatively. On one hand, some people may choose to use marijuana for its capacity to deliver a pleasant high, reduce pain, and alter senses of time and space. On the flip side, some people may choose to avoid marijuana because they fear experiencing a high with undesirable side effects or placing themselves at increased risk for dependence and other ill-health effects. But what are these potential undesirable impacts on he, and how does marijuana contribute to them?

Once marijuana is consumed, the THC and other cannabinoids gradually attach themselves to specific cells in the brain and body known as CB1 and CB2 receptors. Consequently, they affect the functioning of these receptors and may cause marijuana users to experience ongoing problems and health risks, including:

  • Impaired thinking, problem-solving, and memory
  • Poor coordination and balance
  • Elevated risk of cardiovascular disease
  • More frequent respiratory infections
  • Hallucinations (though this primarily occurs when marijuana is taken in high doses)
  • Decreased sperm counts and erectile dysfunction among some males
  • Irregular menstrual cycles among some females
  • Gynecomastia (development of breast tissue in males) after long-term use

However, occasional and short-term marijuana smokers are less likely to experience ongoing problems as a result of using marijuana, as compared to heavy and long-term users. While this may provide some reassurance, it’s crucial to keep in mind that all levels of marijuana use (including light to moderate marijuana use) may still have a complicated relationship with mental illnesses; specifically, for some people, marijuana may alleviate their symptoms of depression and anxiety, whereas for others, it may induce or exacerbate their symptoms, or even induce psychosis.

Finally, to your comment on moderate marijuana use being less dangerous than smoking tobacco or drinking alcohol — that too is unclear. While exhaustive research has shown a clear link between tobacco smoke and cancer, there’s insufficient evidence to suggest that marijuana use may also cause cancer. However, it’s worth noting that marijuana smoke and tobacco smoke do contain many similar compounds, so it may be reasonable to be suspicious of marijuana’s health effects on the body. If someone is comparing marijuana to tobacco and alcohol to guide a decision on whether or not to use it, they may wish to note that, depending on their age, it’s legal to use alcohol and tobacco across the US, whereas the legality of recreational (or medical) marijuana differs from state to state.

Ultimately, the decision to use or avoid marijuana is largely up to the individual. If you have any further questions or concerns about marijuana use you may want to speak with your trusted health care provider who may offer more insight and guidance. You could also check out the Marijuana, Hash, & Other Cannabis category in the Alcohol & Other Drugs Go Ask Alice! archives for more information about marijuana and its effects on the body.

Last updated Apr 06, 2018
Originally published Feb 09, 1996

Submit a new comment


This question is for testing whether or not you are a human visitor and to prevent automated spam submissions.

The answer you entered for the CAPTCHA was not correct.