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Home » Part 6. Medical uses for cannabis – the TL;DR version

Part 6. Medical uses for cannabis – the TL;DR version

Last updated on October 1st, 2020 at 12:43 pm

This is Part 6  of a series of six articles discussing various medical uses for cannabis or marijuana. In this part, I summarize all of the five previous articles into some bullet points so that you have quick and fast access to some scientific information about medical uses for cannabis or marijuana.

In case you missed them, here are the first five articles in this series:

Part 1. Marijuana and medicine assessing the science.

Part 2. Marijuana and cancer – assessing the science

Part 3. Marijuana and neurological disorders – assessing the science

Part 4. Marijuana and health risks – assessing the science

Part 5. Marijuana and pregnancy – assessing the science

Maybe you don’t agree with the science about marijuana’s role in medicine. But that’s not how science works. The evidence should lead you to a conclusion (actually, the acceptance or rejection of a hypothesis). One shouldn’t form an a prior conclusion, then go hunt for data. That’s not how it works.

As new systematic or meta reviews bring more clinical evidence of the benefits of the medical uses for cannabis – this takes time – maybe evidence based medicine can incorporate marijuana into the armamentarium of medical practice. But only real clinical evidence matters.

So let’s review where the evidence leads us.

Medical uses for cannabis – summary


The New York Times reported that New York State had started the legislative process “to join 22 states in legalizing medical marijuana for patients with a diverse array of debilitating ailments, encompassing epilepsy and cancer, Crohn’s disease and Parkinson’s.”

Even though the state of New York eventually legalized it, the New York Times shared their concerns about medical marijuana:

[infobox icon=”quote-left”]…yet there is no rigorous scientific evidence that marijuana effectively treats the symptoms of many of the illnesses for which states have authorized its use. Instead, experts say, lawmakers and the authors of public referendums have acted largely on the basis of animal studies and heart-wrenching anecdotes. The results have sometimes confounded doctors and researchers.[/infobox]

So, does marijuana work to prevent or cure cancer? There is some evidence that it prevents cancer and a little evidence that it can cure cancer. But these are very limited in vivo and animal studies, very preliminary and not in randomized, controlled clinical trials. Just to give a little perspective, less than 8% (pdf) of oncology drugs that enter clinical trials actually end up being approved for use in humans. The failure rate is rather large because the efficacy is generally measured in small amounts for many types of cancers.

For neurological disorders, there are some, but not broad, indicators that THC or its derivatives, could have benefits. But, it’s clouded by the extremely small size of clinical trials, a large potential placebo effect, bad trial design, and different kinds of bias. The systematic reviews tend to heavily qualify their conclusions, mainly because of the lack of large, gold-standard, clinical trials. In other words, there isn’t enough, at this time, for a neurologist to say “this will help.” We don’t know. Which, again, does not mean you can proclaim that if we don’t know, the we do know.

Dr David Gorski, a real oncology researcher, whose knowledge and expertise in these areas matter quite a bit, reviewed the research in many of the medical claims about marijuana and concluded that,

[infobox icon=”quote-left”]There’s no doubt that what is driving the legalization of medical marijuana in so many states has far more to do with politics than with science. Right now, for all but a handful of conditions, the evidence is slim to nonexistent that cannabis has any use as a medicine, and those conditions, such as CINV and chronic pain, can often be treated more reliably with purified or synthesized active components. Moreover, for one condition for which there is reasonably good evidence for the efficacy of cannabis and/or cannabinoids, namely chronic pain, politicians are reluctant to approve medical marijuana.[/infobox]

If politicians want to make marijuana legal, do so because it’s a recreational drug, similar to alcohol. Medical claims should and must be supported by high quality evidence, not internet memes and certainly not by politicians who wouldn’t know any science even if it gave them a $1,000 “donation.”

The world of medical marijuana uses the same weak evidence, the same ignorance of risks, and the same logical fallacies you hear from those who push “natural” herbs or supplements. And the more we look the more we find that there’s nothing there in the world of supplements. We need to separate recreational use of marijuana from medical use. They are not the same, and one shouldn’t support the other.



The TL;DR version


  • Marijuana prevents nausea in cancer treatment patients–maybe, maybe not. No solid randomized clinical trials that support this claim.
  • Marijuana cures cancer–no clinical evidence that it does.
  • Marijuana can treat neurological conditions–not really, but some isolated cannabinoids may help ameliorate some symptoms of some conditions. This area of study has a lot of promise.
  • Marijuana has some risks that have not been fully explored. But stay tuned, I have more to write on this.
  • The quality and labeling of “medical marijuana” is amateurish and potentially dangerous.
  • There is no global Big Pharma conspiracy to suppress clinical research on marijuana. If it could “cure” one cancer, they’d be all over it trying to find the right dose, delivery mechanism, and pretty advertising to make billions of dollars.

If you want to smoke or consume marijuana because it’s relaxing, or you need to blow off steam after a tough day, fine. Go for it. I absolutely do not understand why this usage is illegal. It’s costly to society. And banning it provides no benefit to society.

TL;DR version for marijuana and pregnancy


A high level view of what I’ve read about marijuana and pregnancy when I looked through years of research indexed in PubMed led me to a few conclusions:

  • The most robust research for the actual clinical effects between cannabis and fetal/neonatal outcome has been published over the past 10 years. It shows that there is a link between cannabis use and neurodevelopmental issues.
  • Without showing a true statistical correlation, it appears that most “pro-cannabis” research, which seems to reject a link between the drug and fetal/neonatal outcome, have poorly designed clinical studies with small numbers. And they’re published in the weakest journals.
  • The best evidence, that is the highest quality research published in the highest impact factor journals, strongly suggests (if not concludes) that smoking marijuana during pregnancy reduces neurodevelopmental outcomes for children.
  • But if cherry-picking is the way to go, I could find a handful of poor-quality, unrepeated research to support a belief that consuming marijuana while pregnant (or breastfeeding) is safe. But what we know of many drug’s effects on fetal development (alcohol and cigarettes just to name two), there is a plausible and logical concern about marijuana and the developing fetus.
  • Marijuana and pregnancy (or while breastfeeding) is a bad combination–it is probably not very safe to the fetus or neonate. That’s very clear.



There is a US Patent that has, as one of its statements, “This invention relates to the use of phytocannabinoids, either in an isolated form or in the form of a botanical drug substance (BDS), as a prophylactic or in the treatment of cancer.” There are memes that state that Big Pharma knows that cannabinoids cure cancer or else they wouldn’t have patented it. However, patents do not represent peer-reviewed science, and merely conjecture on the part of the patent holder, so that they may potentially block anyone from manufacturing the drug for the use that it claims.

There is no evidence that this cannabinoid, or any other, has any real potential of treating any disease or condition until such time that there are randomized clinical trials that provide robust evidence that support these claims. In medicine, patents don’t matter, unless you’re a patent lawyer or are trying to invent something new. They provide no information to evidence based medicine regarding marijuana. Drug companies continuously file patents when they even think something might do something. Most drug patents never end up being drugs.

I have heard the strawman arguments and Big Pharma shill gambits that Big Pharma, the FDA, the National Cancer Institute (if the cannabis supporters know it exists), and the US Government suppress all the research that show how great cannabis is for cancer and other clinical indications because those groups don’t want pot to be legal. As amusing as that argument might be (and it’s a fairly bad one), if cannabis or any of its components actually could show efficacy against any of the 200 or so cancers, Big Pharma would be all over it.

Remember, Big Pharma would not be selling joints, they would be isolating the active ingredient, defining the exact dose, determining how to deliver it to the local cancer site in the body, funding clinical trials, filing documentation with the FDA, then getting it into physician’s hands. This is not an easy process, but it would be a profitable one if it worked. Big Pharma and the National Cancer Institute are looking at everything, and they ignore nothing for potential in treating cancers. If cannabis works (and it might), they are all over it. Big Pharma is providing a lot of the funding for it.

Editor’s note: This article is a substantial update of an article (and a few other articles) that was originally published in April 2014. It has been completely revised and updated to include more comprehensive information, to improve readability and to add current research. I’ve also sub-divided into six separate articles to improve readability, and to allow a reader to choose the marijuana and medicine article that is of highest interest.

Another editor’s note: I have a policy of open commenting and dissent to my articles. I only delete spam, racism, and just random nonsense. Please comment here if you wish, because I know everyone has an opinion on marijuana. But ad hominem hatred, strawman arguments and other logical fallacies will be mocked–bring high quality, peer-reviewed evidence. I might even rewrite or add another section if it’s high quality and peer-reviewed.

Michael Simpson

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