An Examination of Medical Marijuana

By Kathleen Doheny. Medically reviewed by Tom Iarocci, MD. May 7th 2016

Fifty-two percent of Americans favor legalizing marijuana, according to a 2013 poll by the respected Pew Research Center, and 20 states and the District of Columbia have legalized medical marijuana. These figures are higher than ever before. The shift in attitude springs, at least partially, from a growing body of research finding more and more health benefits of medical marijuana.

While much more research is needed on marijuana for medical uses, experts do have some agreement on which health conditions marijuana can help. They also have some caveats about doses and who should avoid using pot for what ails them.

Overview of Medical Pot

Marijuana for pain relief is perhaps the most studied area, says Barth Wilsey, MD, associate physician of physical medicine and rehabilitation at the University of California Davis Medical Center and a long-time researcher in the field.

In his own research, he has focused on testing marijuana for patients with nerve pain linked with spinal cord injury, diabetes, shingles or HIV.  He has found that patients with these types of nerve pain often respond to low doses of marijuana. He has tested marijuana in cigarette form and in vaporized form (which releases fewer toxins).

Although people usually smoke far fewer marijuana cigarettes than tobacco cigarettes in a day, chronic marijuana use is associated with some of the same risks as cigarette smoking, including lung cancer, so there is interest in delivering the therapeutic agents while minimizing the toxins.

Patients with chronic nerve pain (a particular type of pain) who were given marijuana reported a 40 percent decline in the intensity of their pain, compared to just a 20 percent reduction in a comparison group not given marijuana, according to an update on medical marijuana reported by Wilsey and others in The Open Neurology Journal.

''No, marijuana doesn't take away all the nerve pain," Wilsey says. "But it's as good as our current drugs. It's really good for nerve pain that is resistant to conventional medicine."

"There's some evidence it works on the brain's glial cells," he adds. "Glia release substances that cause neurons to fire spontaneously, causing the pain."

"I think there is also promise in using it to combat nausea from chemotherapy," Wilsey says of marijuana.

Medical marijuana has also better helped relieve the muscle stiffness affecting patients with multiple sclerosis compared to placebo, other research shows. Adverse events were consistent with known side effects.

Weighing Benefits and Risks of Medical Marijuana

Smoking marijuana is not without health risks. The dose of medical marijuana used should always be the lowest possible, Wilsey says. Today’s marijuana delivers far more THC than in the past. Using higher doses may induce a mental fog — not good for anyone trying to be productive, but especially harmful for those with certain conditions such as multiple sclerosis (MS). MS patients are already at risk of cognitive decline due to the disease's effect on brain cells.

The goal, says Wilsey, is to determine the dose effective for the condition, without compromising thinking abilities.

Taking the Next Steps

Wilsey has this advice for those thinking of using medicinal marijuana:                                         

  • Consider your individual health situation. "In people with coronary artery disease, for instance, it raises the heart rate," he says, which is a potentially harmful consequence. Pregnant women should also abstain.
  • Do not smoke and drive.
  • Do not expect too much. Marijuana is by no means a magic remedy. However, in some studies, it has been shown to work as well as conventional treatments or to work when conventional treatments have failed.

For Caregivers

If a loved one has pain or another condition that isn't responding to conventional treatments, you might ask his physician if medical marijuana is a possibility.

If a loved one suffers from a condition for which medicinal marijuana has not yet been studied, you can help by searching to see if a clinical trial is ongoing. See

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