Medical marijuana

Peter Grinspoon, MD

Contributing Editor

There are few subjects that can stir up stronger emotions among doctors, scientists, researchers, policy makers, and the public than medical marijuana. Is it safe? Should it be legal? Decriminalized? Has its effectiveness been proven? What conditions is it useful for? Is it addictive? How do we keep it out of the hands of teenagers? Is it really the “wonder drug” that people claim it is? Is medical marijuana just a ploy to legalize marijuana in general?

These are just a few of the excellent questions around this subject, questions that I am going to studiously avoid so we can focus on two specific areas: why do patients find it useful, and how can they discuss it with their doctor?

Marijuana is currently legal, on the state level, in 29 states, and in Washington, DC. It is still illegal from the federal government’s perspective. The Obama administration did not make prosecuting medical marijuana even a minor priority. President Donald Trump promised not to interfere with people who use medical marijuana, though his administration is currently threatening to reverse this policy. About 85% of Americans support legalizing medical marijuana, and it is estimated that at least several million Americans currently use it.

Marijuana without the high

Least controversial is the extract from the hemp plant known as CBD (which stands for cannabidiol) because this component of marijuana has little, if any, intoxicating properties. Marijuana itself has more than 100 active components. THC (which stands for tetrahydrocannabinol) is the chemical that causes the “high” that goes along with marijuana consumption. CBD-dominant strains have little or no THC, so patients report very little if any alteration in consciousness.

Patients do, however, report many benefits of CBD, from relieving insomnia, anxiety, spasticity, and pain to treating potentially life-threatening conditions such as epilepsy. One particular form of childhood epilepsy called Dravet syndrome is almost impossible to control, but responds dramatically to a CBD-dominant strain of marijuana called Charlotte’s Web. The videos of this are dramatic.

Uses of medical marijuana

The most common use for medical marijuana in the United States is for pain control. While marijuana isn’t strong enough for severe pain (for example, post-surgical pain or a broken bone), it is quite effective for the chronic pain that plagues millions of Americans, especially as they age. Part of its allure is that it is clearly safer than opiates (it is impossible to overdose on and far less addictive) and it can take the place of NSAIDs such as Advil or Aleve, if people can’t take them due to problems with their kidneys or ulcers or GERD.

In particular, marijuana appears to ease the pain of multiple sclerosis, and nerve pain in general. This is an area where few other options exist, and those that do, such as Neurontin, Lyrica, or opiates are highly sedating. Patients claim that marijuana allows them to resume their previous activities without feeling completely out of it and disengaged.

Along these lines, marijuana is said to be a fantastic muscle relaxant, and people swear by its ability to lessen tremors in Parkinson’s disease. I have also heard of its use quite successfully for fibromyalgia, endometriosis, interstitial cystitis, and most other conditions where the final common pathway is chronic pain.

Marijuana is also used to manage nausea and weight loss, and can be used to treat glaucoma. A highly promising area of research is its use for PTSD in veterans who are returning from combat zones. Many veterans and their therapists report drastic improvement and clamor for more studies, and for a loosening of governmental restrictions on its study. Medical marijuana is also reported to help patients suffering from pain and wasting syndrome associated with HIV, as well as irritable bowel syndrome and Crohn’s disease.

This is not intended to be an inclusive list, but rather to give a brief survey of the types of conditions for which medical marijuana can provide relief. As with all remedies, claims of effectiveness should be critically evaluated and treated with caution.

Talking with your doctor

Many patients find themselves in the situation of wanting to learn more about medical marijuana, but feel embarrassed to bring this up with their doctor. This is in part because the medical community has been, as a whole, overly dismissive of this issue. Doctors are now playing catch-up, and trying to keep ahead of their patients’ knowledge on this issue. Other patients are already using medical marijuana, but don’t know how to tell their doctors about this for fear of being chided or criticized.

My advice for patients is to be entirely open and honest with your physicians and to have high expectations of them. Tell them that you consider this to be part of your care and that you expect them to be educated about it, and to be able to at least point you in the direction of the information you need.

My advice for doctors is that whether you are pro, neutral, or against medical marijuana, patients are embracing it, and although we don’t have rigorous studies and “gold standard” proof of the benefits and risks of medical marijuana, we need to learn about it, be open-minded, and above all, be non-judgmental. Otherwise, our patients will seek out other, less reliable sources of information; they will continue to use it, they just won’t tell us, and there will be that much less trust and strength in our doctor-patient relationship. I often hear complaints from other doctors that there isn’t adequate evidence to recommend medical marijuana, but there is even less scientific evidence for sticking our heads in the sand.

Related Information: Harvard Health Letter


  1. Zman

    What about Cardiovascular effects of Marijuana? There so many different opinions and contradictions in research online i dont even know what to listen to. And because its so politically polarized with politicians and special interest (Big Pharma?) i dont even know which research to believe.

    • Peter Grinspoon, MD

      According to the National Academy of Sciences, Engineering and Medicine, “There is no evidence to support or refute a statistical association between chronic effects of cannabis use and the risk of acute myocardial infarction.” I recommend that you read any literature that purports to show any such claims very carefully because, as you alluded to in your question, this issue has become very politicized. For example, some studies may imply cannabis causes some or other ill consequence but, if you actually read the study carefully, the cannabis and the ill consequence are just randomly associated, and have no causal relationship to each other whatsoever, and may even be caused by the same root causes. The science on both sides of this issue needs to improve, and the federal government needs to lift restrictions on studying it’s medical utility.

      • Zman

        Thanks for your reply. I agree and there needs to be a lot more non byas research especially for medical marijuana patients that are concerned about there heart and health. It would be nice to know the real effects and what we are dealing with.

  2. Plantelys

    Thank you very much for sharing this great article about Medical Cannabis. You are most welcome to take a look at this article, about the same topic:


    Thank you for this blog. It is interesting as well as informative.
    When a person is prescribed by her Doctor marijuana for let’s say for pain.
    Does one go to the pharmacy to pick up your med?

    What where are the companies that make and dispense
    This drug?

  4. Muriel Zimmer

    Thank you for this wonderful article.

    Please inform me of any relevant research supporting pain control of osteo arthritis and/or chronic muscle pain due to traumatic injuries using cannabis based medical products. I’d like to avoid intoxicating aspects of cannabis as it increases my anxiety.

    As a Canadian I am pleased to report the legality of using cannabis is confidently striding into the near future. Keep the pressure on in the USA to legalize this plant’s use.

    Thank you.

    • Peter Grinspoon, MD

      CBD predominant strains are less likely to be anxiety producing than high THC strains. Good luck!

      • Mark Morgan

        Agree re Paranoia we need better education I spent years consuming high strains of THC it definitely takes its toll on lots of people, however even a strain that’s high in THC seems be all good when mixed with a healthy dose of CBD.

        I am from the UK Americans and Canadian’s should consider themselves very lucky as I am constantly fighting the battle of educating my doctor and family members ☮

  5. George M. de Vera

    Hi Peter,

    How about marijuana to cure diabetes? Can this lower our sugar level in our body?

  6. khadijah tribble

    I really appreciate this piece. I’m working on the policy side over at the Kennedy School. As a SICI fellow my focus is on solving the problem of misinformation and missing information and chaos of regulating a highly politicized controlled substance. There are huge gaps in our knowledge and credible analysis of the information that is available.
    We need responsible and equitable cannabis regulations that aren’t punitive to patients and consumers but doesn’t restrict the market while also mitigating the economic devastation caused by ‘war on drugs’. I’ve been looking for counterparts in at the Harvard Med School or Chan School of Public Health to be a part of the Marijuana Policy Trust think thank. Do you have any suggestions of who I should reach out to? My email is

  7. Roberto

    Hello Peter, I am currently writing a research paper on the benefits of medical marijuana and was wondering if you could provide me with a few reliable sources, or maybe a list of benefits?

  8. Daniele Merkov

    Is it true that marijuana can actually help to loss weight? I’ve been hearing people talk about this lately in some forum i cant remember what forum that is but i was pretty curious about they’re topic. I have been reading this marijuana strain here in and all it says that it can help you relax and chill you physically and mentally. Some of them might even help you with depression and anxiety but this issue regarding losing weight when using marijuana is just fascinating. Can you enlighten me with some new information about this?

  9. Holly Martin

    How can the top Universities and colleges in the United States teach about the therapeutic, medicinal benefits of cannabis if it’s classified as schedule 1? The US government is adamant that there are none. If you, Harvard, are saying that there are benefits, how is it legal to keep the classification the same?
    What is going on here?

    • Peter Grinspoon, MD

      “Harvard” has many different faculty members who likely hold many different views on medical marijuana; this blog doesn’t attempt or purport to speak for all of them. That said, you are correct that there is a dichotomy between the the government’s classification of marijuana as having “no medical benefit” and this article which cites about a dozen areas where marijuana has been demonstrated to be beneficial. Unfortunately, our government’s policy is vastly out of step with the reality that millions of patients are experiencing, and with modern scientific evidence. It needs to change. (The history of our nation’s “War on Marijuana” is fascinating to read about; it is mostly based on racism as well as politics against the anti-Vietnam left…long story!).

      • Holly Martin

        Thank you so much for your honest, unbiased, reply.
        It is very appreciated.

        Holly Martin

      • Holly Martin

        Also, this may be a question that you may not be able to, or want to answer, but, does the classification have anything to do with giving up the monopoly in regards to research?
        Is it about the money?
        Something is very wrong here.

  10. FredyJohnSmith

    A complete comprehensive article I will say. Looking at the benefits it can offer, it should be legalised. Thanks for the share.

  11. Michelle

    I am 46 and have suffered from migraines for nearly 25 years. They have become less frequent ( a few per month instead of a few per week), but harder to control with rescue medications such as relpax. For 2 months in a row now I have had to take a steroid to get rid of the headache which had lasted for more than 5 days. I have tried several preventative medications over the years (lyrica, topomax, Elavil, botox, Effexor, occipital nerve block injections etc), with fleeting success. I also suffer from chronic neck tension and pain resulting from disc bulges caused by a previous accident which exacerbates the headaches.

    I live in Florida and have been told that I automatically qualify for a medical marijuana card as I am a breast cancer survivor (3 years in remission). However, I am worried about the stigma and potential political/social complications of a marijuana prescription. I work full-time, have 2 small children, and am pursuing my MBA. I need to be fully functioning. Period. I am MOST concerned about any contraindications that it might have on Tamoxifen that I have been prescribed to take for 7 more years. Not sure that I can handle the anxiety of wondering, what if…

    Any suggestions that you have or research that you can share would be greatly appreciated.

    Thanks so much.

  12. Jože Skrbinek

    hello, my best friend have ALS disease. Do you have any experiance with this disease, medical CANABIS-ALS. He is 55 years old.
    Thanks for answer.

    best regards from Slovenia

  13. Lisa M Kaelin

    I’m 58 years and have been battling brain inflammatory disease. 20 years of autoimmune diseases, surgeries, every type of inflammatory disease and many prescriptions. Finally enough bullshit!!! I took my life in my own hands cold turkey off 20 years of pills. Maybe not the smartest thing to do however with weed I did it. I can’t believe how functional I have become. Not cured but I can manage my life with weed and probiotics. I have my brain back. My pain is way down. I don’t cry anymore about being sick. I’m not in a fetal position from pain. No one needs to suffer…it’s not like they will give you a medal for it. Weed is life changing and healing and hopeful!!

  14. P L Burr

    Isn’t smoking ANY substance but for your lungs?

    • Peter Grinspoon, MD

      There are many different ways to consume medical marijuana: drops under the tongue, edibles, tinctures, vaporizing it, topical treatments; it is not recommended (at least by doctors…) that people smoke it (though, interestingly, it hasn’t been linked to lung cancer in the studies I’ve seen).

      • Jo Ann

        Actually, several studies have compared the lungs of a marijuana smoker to those of a tobacco user, and the marijuana smokers have had a much higher lung capacity. Some studies have also showed that repetitive marijuana use can eventually slow the effects of tobacco. It still has not proven “medically beneficial”, and more studies need to occur before any judgement can be made. THC in marijuana has been proven to bind to the brain cells that relate to, and control excitability and relaxation.

  15. Elizabeth Pallett

    OK lets begin by removing a couple of things, the medical/recreational and more importantly get rid of the marijuana prohibition term, use the plants correct name and then perhaps patients might not be so confused, its name is Cannabis.

    All Cannabis should be grown organically, never have the males removed and the object is to gain as many of the 140 cannabinoids as possible to bring about whole health.

    How the oils and tinctures are made are very important and given the USA is getting it completely wrong and are now years behind what we in the Cannabis compassion suppliers are finding and now know.

    The research is being done, it is simply not being done by big pharma or governments.

    There is absolutely no health or safety risk using Cannabis from conception to the grave. Anyone and everyone should be able to grow the plant and use it as they please as you should any other herb or vegetable, it should not be on a drugs list and it should not be under the control of drug companies or the medical profession.

    Time to end the war on a plant and heal the planet.

    • Peter Grinspoon, MD

      My father is Dr. Lester Grinspoon, the “grandfather” of medical marijuana (a.k.a. cannabis), who has been fighting to legalize this ever since his book ‘Marihuana Reconsidered’ [sic] came out in 1971, so I’m not unsympathetic to your position. 🙂

  16. Sonny Chandler

    If THC is removed, is there pain relief? In other words — is there pain relief and PTSD help etc. etc when the THC chemical that makes people high removed from medical marihuana ?

  17. Justin Escher Alpert

    “We can only hope that within the next decade the effects of the “war on drugs” will start to fade and give way to a more comprehensive and fact-based understanding of all bioactive substances. So whether you reach for the medicine bottle or the lighter, you’ll understand just how each dose will affect you, the benefits and risks of consumption, and the potential for abuse—and, however you choose to use these substances, you’ll have greater assistance from our health care system and a more open-minded society to support your choices.” –

  18. Joe

    Hi Peter,

    It is a very emotive subject. As I see as Governments etc can make money from medical marijuana then they will take it on board. It is a nonsense that the large pharma countries are legally killing people and it is only recently that many of us are waking up to natural medicine. Take the large alcohol manufacturers, lover the world over by Governments and their paymasters as it generates so much revenue for them. This is despite the devastation that this drug causes to some many families the world over.


  19. Cat Motors

    Hi Peter!
    Tell me please, is there any statistics on how the number of traffic accidents has changed after some states of the USA have allowed the use of marijuana? It would be interesting to know statistics on cars and motorcycles. We stay in Chiang Mai (Thailand), and sometime have are heated discussions and disputes about this among rental owners =)

  20. Valerie Tikhonoff

    Information on drugs interaction are rare. Do you know the intersections with new oral anticoagulants such as Apixaban? One of my patient with ALS got a recurrent pulmonary embolism on treatment with apixaban and oil cannabis.

  21. alfonso

    Cannabis oil extraction is advancing quite dramatically as well. The cannabinoids and terpenes can be extracted in a number of ways including ethanol/hydrocarbon soak, distillation, even a press (similar to a t-shirt press) using heat and pressure to literally squeeze the oils out of the cured flowers. The healing properties of these oils can even be recombined to specifically treat different types of ailments. What is needed, is more information to identify which compound from the plant that is aiding their specific ailment. Even if someone has not had a beneficial experience with one of the strains they have chosen to use, there is a myriad of other strains with different ratios/percentages of terpenes/cannabinoids. Genetic profiles of strains are even being mapped to aid researchers in identifying which may best be helpful to patients in the future.

    • Peter Grinspoon, MD

      Thank you for your interesting comment!

      • alfonso

        You’re very welcome. There is a small but very dedicated community out to gather hard data and empirical evidence on the matter to go along with the patient’s accounts. Of course, it is expanding every day because of articles like this and doctors like you, but I digress. There are legitimate benefits to cannabis which can improve the quality in many aspects of life and it is just unfortunate that progress for people’s health and well-being has to be sacrificed amongst the geopolitical scene to line already wealthy wallets and/or egos of already powerful people. The archaic views putting marijuana in the Schedule 1 rating along with heroin, methamphetamines, etc. need to be changed first and foremost because it truly is ludicrous to insinuate that cannabis has no medical benefits.

    • Harry Conroy

      To Alfonso and others interested,
      What about Rick Simpson Oil ( R.S.O. ) ?
      I reference the life experience of Canadian entertainer Alan Park
      ( Royal Canadian Air Farce sketch comedy ensemble, popular national Canadian comedy television show ).
      He used RSO in a suppository form and purportedly reduced his
      psa blood test from around 700 to close to zero, over maybe a five
      month period !
      He was diagnosed at stage four prostate cancer after going to the
      Doctor for an unrelated complaint, and subsequent diagnostic tests
      revealed his totally unsuspected, and late stage, prostate cancer.
      He apparently could not be offered any conventional treatment
      per the assessment of his Physician due to the advanced stage
      of his prostate cancer condition.
      The Doctor gave him about three months to live. He has celebrated
      three years of survival since that initial cancer diagnosis.
      Rick Simpson is a Canadian citizen that apparently has been under
      legal duress associated with his total marijuana plant conversion
      to oil concentrate of some sort. Alan Park uses the RSO in suppository
      Alan Park has an online pod cast called, GREEN CRUSH, which
      is related to marijuana issues, medical marijuana, and his
      personal experiences.
      If his health story journey is accurate, and positively in support of prostate cancer
      treatment in a genuinely efficacious and measurably evidenced
      based way, we should get our interest directed in this area
      of inquiry, most ricky ticky !
      It certainly sounds compelling to me, at least on the face of his
      narrative of his very unconventional personal experience and

  22. SAM Action

    Doctors are the leading cause of Opioid addiction in America. They continue to prescribe Oxycontin like it was candy and then after the prescription runs out, their patients turn to the only available alternative; Afghanistan grown US Military protected Heroin. The greatest threat to American youth is the ignorance and arrogance of the AMA and a Federal Government that refuses to consider Marijuana as an adjuvant for pain mitigation.

    Shame on us for tolerating a corrupt alcohol-based establishment and perpetuating the 1937 Nazi-era marijuana prohibition laws.

    • Rona Clayton

      I agree fortunately I never took opiates until I was legally prescribed them in 2004 after a MRI and my diagnosis for back pain and in my town we don’t have heroin and yes I was on oxycontin years ago and when I had to detox off of them due to unfortunate circumstances I thought I was dying I never want to experience that again

  23. Craig Gillette

    I’ve been using DC medical marijuana for four years now, to treat my fibromyalgia, other health issues, and even my addiction recovery. Marijuana is non-toxic and safe to use every day, and I’m having great success with it. So are millions of others of people. Pills kill, cannabis heals. I’ve been smoking cannabis for four decades, I don’t need no scientist or Dr. to tell me the magic that it contains. They need to convince and educate themselves. They need to remember the Hippocratic oath to first do no harm, and death pills are killing people every 15 minutes in America. Stop with the pills already !!!!!!

    • Peter Grinspoon, MD

      Glad you found the treatment that works for you!

      • Jeffrey

        Thank you, Sir Your Blog is very nice and valuable for everyone who doesn’t know about Marijuana and it benefits which are related to health. Here you describe Marijuana legalization, use regarding health and Pain control but they should take it after getting a recommendation from MMJ doctor, Which is very necessary.
        Online Medical Card also Providing Services for having Marijuana legally after Recommend by the doctor.

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