Michael Hunter, MD on Medika Life

In the Weeds: Unveiling Medical Marijuana Uses

WANT TO STIR UP CONTROVERSY? Start talking about marijuana. Is it safe? Should it be legal? Are there health benefits? Harms? Is weed addictive? This essay goes in the weeds, unveiling medical marijuana uses.

I would be remiss if I did not begin with a clip from the Ambassador of Weed, Snoop Dogg:

Snoop Dogg Is The Ambassador Of Weed | CONAN on TBS

Do Americans Support Legalizing Marijuana?

Marijuana is legal for adults in 22 states and Washington, DC. Medical marijuana is legal in 38 states and D.C.

Cannabis is an illegal Schedule I drug, according to the U.S. federal government.

What percentage of Americans do you think support legalizing marijuana? 25 percent? 53 percent? 88 percent? If you guessed the last, you are correct.

An overwhelming share of U.S. adults say that marijuana should be legal for medical and recreational use by adults (59%) or that it should be legal for medical use only (30%).

Just one in ten Americans say marijuana use should not be legal, according to a 2022 Pew Research Center survey.

Over the long term, there has been a steep rise in public support for marijuana legalization.

Let’s turn to some basics and then address selected medical uses of marijuana.

What’s in Marijuana?

Marijuana — the dried leaves known by names such as weed or pot — comes from a genus of flowering plants called Cannabis.

Cannabis plants have over 100 chemicals (cannabinoids) that affect the human nervous system.

Some chemicals stimulate brain parts, while others block the same effects. The best-known plant-based cannabinoids are:

  • T.H.C. (D9-tetrahydrocannabinol): the psychoactive component of cannabis that can make one feel “high.” Sativa strains of (Cannabis sativa) tend to have higher T.H.C. concentrations than others. Today’s marijuana typically has 10 to 30 times the amount of T.H.C. from the 1970s.
  • CBD (cannabidiol): This cannabis component may have calming effects on the nervous system. CBD doesn’t have the psychoactive effects of T.H.C. Therudaralis, and indica cannabis strains (Cannabis indica and Cannabis rudaralis and cannabis indica) tend to have less T.H.C. and more CBD.

Marijuana — Medical Use in General

The most common use for medical medical marijuana in the U.S.A. is for pain control.

My patients with severe pain do not generally respond to marijuana. On the other hand, the drug can be effective for chronic pain.

Photo by Robert Nelson on Unsplash

Many of my patients prefer a trip to their local marijuana dispensary. Part of the appeal is that it is safer than opiates.

Folks don’t generally overdose on marijuana*; weed is far less addictive.

Others cannot tolerate NSAIDs (for example, Aleve or Advil) because of kidney or stomach problems.

  • Overdose is also possible with edible cannabis (though an overdose on cannabis is rarely fatal). Users taking it by mouth may not notice any effects for up to two hours. They may then ingest more, thinking they need a higher dose, and take too much.

Marijuana Use for Multiple Sclerosis

Here’s an example of the use of marijuana in medicine: Multiple sclerosis. The drug can ease pain (including nerve pain).

Alternative medicines (such as Lyrica, Neurontin, and opiates) can cause sedation for many. Enter marijuana:

Nearly one in three adults with multiple sclerosis report using cannabis for pain management.

Oil or tincture is the preferred method of administration, according to a survey of over 200 individuals.

Does Marijuana Relieve Multiple Sclerosis Pain?

Evidence for cannabis effectiveness for MS-related pain is limited, according to a 2022 Cochrane ReviewThe researchers offer this conclusion:

We are uncertain whether cannabinoids reduce chronic nerve pain intensity.

On the other hand, for spasticity (feelings of stiffness and a wide range of involuntary muscle spasms), more people reported benefits with cannabinoids than with placebo.

For their review, the Cochrane Review authors analyzed randomized clinical trials. These studies examined herbal Cannabis, Cannabis flowers, plant‐based cannabinoids, or synthetic cannabinoids.

The doses, routes of administration, frequency, and duration of use for those with multiple sclerosis varied.

Slightly more people on cannabinoids quit the medicine than did those on placebo. The absolute effect was 39 more people per 1,000 people.

Marijuana Use for Parkinson’s Disease Tremors?

Marijuana can be a very good muscle relaxant. Might it help lessen the tremors associated with Parkinson’s disease?

The National Aging Institute explains that Parkinson’s disease (P.D.) is a brain disorder that causes unintended or uncontrollable movements, such as shaking, stiffness, and difficulty with balance and coordination.

Unfortunately, P.D. symptoms usually begin to worsen over time gradually.

With disease progression, some have challenges talking or walking. Others experience behavioral changes, sleep issues, memory difficulties, fatigue, and depression.

Nerve cells. Adobe Stock Photos.

The Parkinson’s Foundation offers some possible benefits of marijuana for those with Parkinson’s disease:

  • Anxiety reduction
  • Pain improvement
  • Better sleep
  • Less weight loss
  • Nausea improvement

Of course, marijuana use has associated risks. These include:

  • Impaired cognition (especially in executive function and judgment). Researchers worry about marijuana use for a medical condition associated with executive function impairment.
  • Dizziness
  • Mood changes
  • Blurred vision
  • Balance problems
  • Hallucinations

Marijuana can increase the risk of mood disorders (especially among young users) and lung cancer.

Does Marijuana Help Parkinson’s Disease Tremors?

Given marijuana is a great muscle relaxant, does it lessen tremors for those with Parkinson’s disease?

While some studies are encouraging, many problems have plagued much of the research.

The studies are generally small and lack a comparison group that receives a placebo). There is often no standardized dosing and no comparison with existing treatments.

In this context, the Parkinson’s Foundation does not endorse the use of cannabis for Parkinson’s disease treatment because of the lack of definitive data.

A Greman survey suggests marijuana use is linked to pain and muscle cramp improvement.

Selected individuals may see positive results for anxiety, depression, motor symptoms, and restless leg syndrome.

Unfortunately, the survey had a low response rate and a possible placebo effect.

Marijuana for Glaucoma

Glaucoma is among the most frequent reasons for medical marijuana use.

Research from the 1970s shows that marijuana and T.H.C. reduce intraocular (within the eye) pressure, a key contributor to glaucoma.

Glaucoma is a group of eye conditions that damage the optic nerve. This nerve sends visual information from your eye to your brain, which is vital for good vision.

Optic nerve damage is often related to high pressure in your eye. However, glaucoma can occur even with normal eye pressure.

While glaucoma can occur at any age, it is more common among older individuals. My late dad developed the condition in his 30s, as did his mother and several brothers.

Glaucoma is a leading cause of blindness for people over 60.

Does Marijuana Help With Glaucoma?

Several studies have shown that cannabinoids or marijuana reduce intraocular pressure (I.O.P.).

Marijuana is as effective as conventional glaucoma medicines.

Cannabinoids effectively reduce eye pressure, whether administered by mouth, vein, or inhalation. However, direct application to the eye does not work.

In most trials, a single dose of marijuana or cannabinoids maintained the eye pressure drop for three to four hours.

Marijuana, Nausea, and Weight Loss

A few small clinical trials investigating smoked marijuana show it can help treat nausea and vomiting from cancer chemotherapy.

A few studies have found that inhaled (smoked or vaporized) marijuana can reduce neuropathic pain (pain caused by damaged nerves).

Photo by National Cancer Institute on Unsplash

The American Cancer Society observes that scientists have reported T.H.C. and other cannabinoids (including CBD) slow growth or cause the death of certain types of cancer cells growing in lab dishes.

Moreover, some animal studies suggest certain cannabinoids may slow growth and reduce the spread of some cancer forms.

Dronabinol can reduce nausea and vomiting linked to chemotherapy.

The drug can also improve appetite and prevent weight loss in patients with H.I.V. In studies of cancer patients, though, it did no better than a placebo or another drug (megestrol acetate).

I look forward to seeing more evidence of the effects of cannabinoids in treating cancer in humans. While the approach seems relatively safe, we do not know if the drugs will help control or cure cancer.

Relying on marijuana alone as treatment (while avoiding or delaying conventional medical care) for cancer can have serious health consequences.

Marijuana and PTSD

Finally, marijuana appears promising for those with post-traumatic stress disorder (PTSD).

Many war veterans report significant improvements in their symptoms.

A placebo-controlled, double-blind study published in PLOS ONE is the first randomized placebo-controlled trial of smoked cannabis for PTSD.

All treatment groups, including placebo, showed good tolerability and significant improvements in PTSD symptoms during three weeks of treatment, but no active treatment statistically outperformed placebo in this brief, preliminary trial.

We need much more research to understand the effectiveness and safety of cannabis in treating PTSD.

What doses are optimal? Are there sex differences? What are adverse outcomes? What is the best ratio of T.H.C. relative to CBD?

Finally, could cannabis (or some of its components) help create a bridge to psychotherapy?

Considerable research in animals has pointed to the benefits of cannabinoids in the treatment of PTSD.

My Thoughts — In the Weeds: Unveiling Medical Marijuana Uses

I have not tried to create a comprehensive list of all of the conditions for which marijuana may be beneficial.

Rather, I wanted to briefly survey the types of conditions for which medical marijuana has been touted as beneficial.

Please evaluate any effectiveness claims critically and with caution. In addition:

  • Inform your healthcare provider. Marijuana can interact with some prescribed medicines. Some care providers are not open to the idea of medical marijuana or don’t feel comfortable filling out state-mandated paperwork. If so, consider finding a clinician who can work with you. Finally, medical marijuana should be approached as a complementary therapy, not a substitute for appropriate medication.
  • Cannabis products are often not regulated.
  • Not all marijuana products are the same. Even if two products contain the same strain, for example, the cannabinoids in them may be different and have different effects.
  • Stay consistent and start with a low dose. Stay with the same product from the same dispensary or source to get the most consistent dose.
  • Avoid smoking. Oral drops can be an effective alternative.
  • Consider using skin creams or patches for localized pain. Topical marijuana derivatives can serve as an analgesic for certain areas (for example, the legs).

Have you used marijuana for medical purposes? If so, did it work for you?


Medika Life has provided this material for your information. It is not intended to substitute for the medical expertise and advice of your health care provider(s). We encourage you to discuss any decisions about treatment or care with your health care provider. The mention of any product, service, or therapy is not an endorsement by Medika Life

Michael Hunter, MD
Michael Hunter, MD
I received an undergraduate degree from Harvard, a medical degree from Yale, and trained in radiation oncology at the University of Pennsylvania. I practice radiation oncology in the Seattle area.

Michael Hunter, MD

I received an undergraduate degree from Harvard, a medical degree from Yale, and trained in radiation oncology at the University of Pennsylvania. I practice radiation oncology in the Seattle area.

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