ADVERSE EFFECTS LINKED TO MEDICINAL MARIJUANA

Users Experience More Drowsiness, Dizziness Than Non-Users, Research Finds

The use of medical marijuana to relieve pain and other disease
symptoms can cause a huge range of adverse effects, says an analysis
of safety studies co-authored by University of B.C. and McGill
University researchers.

The researchers evaluated 31 studies done around the world during the
past 40 years and found that while nearly 97 per cent of adverse
events were not serious or life threatening, medicinal marijuana
users still have an 86-per-cent increase in the rate of non-serious
adverse effects like drowsiness and dizziness compared to non-users,
according to the study in the June 17 Canadian Medical Association Journal.

The risk of suffering serious, adverse effects requiring
hospitalization is not elevated in medicinal marijuana users,
compared to non-users, according to the study. But studies on
patients taking marijuana have nevertheless shown that serious
effects have rarely been documented, including multiple sclerosis
relapses, convulsions, respiratory and gastrointestinal disorders,
urinary infections, cancer tumour progression and psychiatric disorders.

Research on recreational marijuana users who smoke cannabis shows
they have an increased risk for psychosis and cancer, but the authors
say no one should assume that the same effects would apply for those
using it for medicinal purposes, due to different delivery systems and doses.

It's too early to say if medicinal marijuana predisposes patients to
a higher risk of death or other serious events. In the current study,
there were 15 deaths among 164 adverse events in 1,932 marijuana
users but the authors couldn't say whether they were directly related
to -- or hastened by -- the marijuana products or whether underlying
diseases caused the deaths.

There were three deaths in 60 adverse events in the control group of
1,209 non-users but the authors say there is no statistical
difference between the two groups to show an increased risk of death
from medicinal marijuana.

They stressed that 99 per cent of the serious adverse events were
reported in only two major studies, which proves that plenty more
research needs to be done to make any conclusions about safety issues.

Dr. Jean-Paul Collet, one of the study authors who is a UBC professor
and pediatrician leading clinical research at B.C. Children's
Hospital, said in an interview that because of the small numbers of
cases and patients, it's impossible to say whether the serious
effects were directly related to the cannabis products.

"There is statistical validity to the non-serious effects like
nervousness, paranoia, hallucinations, dizziness and anxiety. But it
would be incorrect to talk about cannabis medicines causing an excess
risk of death at this point. We cannot make any conclusions about any
of the serious events. We need more information and more research in
order to see whether there are any trends," said Collet, who
previously worked at McGill University when the study was undertaken.

Collet said he wasn't surprised about the non-serious adverse events
because marijuana is known to impact the central nervous system. The
study confirms that short-term use of existing medical marijuana
agents increase the risk of non-serious adverse events, he said. But
since all the studies analysed were short term (median of two weeks)
the effects of long term use are poorly understood and high-quality
trials are needed.

As of a few months ago, 2,432 people in Canada were legally
registered as medicinal marijuana users. There are four different
medicinal products available in Canada, more than any other country.
The products include an herbal extract in a spray form called
Sativex; some oral (pill form) products called Marinol and Cesamet
and an herbal plant form, which may be smoked or used as a food ingredient.