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 After reviewing 80 randomized trials that included nearly 6,500
people, researchers found moderate support for using marijuana to
treat chronic pain and muscle spasms and involuntary movements.
The evidence wasn't as strong to support marijuana's use for nausea
and vomiting due to chemotherapy, sleep disorders, HIV-related
weight loss and Tourette syndrome.
Also, any benefits of marijuana or cannabis use must be weighed
against the risk of side effects, which include dizziness, dry
mouth, nausea, sleepiness and euphoria, according to the study's
lead author.
"Individuals considering cannabinoids as a possible treatment for
their symptoms should discuss the potential benefits and harms with
their doctor," said Penny Whiting of University Hospitals Bristol
NHS Foundation Trust in the UK.
She also told Reuters Health by email that other reviews of medical
marijuana suggest prolonged use may be tied to an increased risk of
psychosis.
The new review, which is published in the Journal of the American
Medical Association (JAMA), was commissioned by the Swiss Federal
Office of Public Health. The researchers searched medical databases
for past randomized controlled trials, which are considered the
"gold standard" of medical research.
While the researchers found that most trials suggested some
improvements in symptoms for the various conditions, not all could
suggest the improvement wasn't just due to chance.
"As systematic reviewers, we have provided a summary of the
available evidence which doctors can now use to make decisions
regarding whether to prescribe cannabinoids for their patients,"
Whiting said.
A second review published in the same journal by Dr. Kevin Hill of
McLean Hospital in Belmont, Massachusetts, found similar results.
In that review, Hill found high-quality evidence to support the use
of marijuana in people with chronic or neuropathic (nerve) pain, and
muscle problems related to multiple sclerosis.
"The two reviews have reached similar conclusions, that while there
is some evidence to support the use of marijuana for certain
conditions . . . for many of the other conditions that various U.S.
states have approved medical marijuana, the evidence is of low
quality," said Dr. Deepak Cyril D’Souza of Yale University School of
Medicine in New Haven, Connecticut.
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As of March 2015, 23 states and the District of Columbia allow
marijuana use for medical purposes.
"If the primary process by which medications are approved for
'medical' use in the U.S. is the (Food and Drug Administration)
approval process, then the evidence for many conditions does not
meet the existing threshold of evidence," said D'Souza, who
co-authored an editorial accompanying the new reviews.
In another study in the same journal, researchers found poor
labeling on medical marijuana.
Of 75 edible marijuana products purchased in three metropolitan U.S.
areas, less than one in five were labeled correctly, according to
Ryan Vandrey of Johns Hopkins University in Baltimore and
colleagues.
They found the vast majority of products contained more or less of
the active ingredients than the label indicated.
In his editorial, D'Souza and his co-author say patients may have to
experiment with different types of marijuana to achieve the desired
effects.
"Both patients and doctors should demand that the government support
high quality research to conclusively determine whether marijuana
has therapeutic effects in the various conditions for which it has
been currently approved," D'Souza said.
SOURCE: http://bit.ly/1TLbzaa, http://bit.ly/1IwCptX, http://bit.ly/1de01L8
and http://bit.ly/1Jgqnuf JAMA, online June 23, 2015.
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