Every once in a while in medicine a new discovery comes
along that, on its face, seems to make no sense at all. What if I were to tell
you that a popular drug – one that’s been sampled by two out of every five Americans
and is renowned for its relaxation and anti-nausea properties – could actually cause
severe bouts of nausea and vomiting among long-term users? These symptoms are
worse in the morning and seem to be most effectively relieved by a long hot
shower. Hmmm, smells a bit skunky, right? But, recently published reports seem
to confirm the phenomenon. And, you might be more than a bit surprised by the
culprit: THC.
Cannabinoid hyperemesis (THC associated vomiting) was first
described in 2004 but remains a relatively unknown and underappreciated malady.
A recent case series by Douglas A. Simonetto and colleagues at the Mayo Clinic
in Rochester, MN, compiled data on 98 patients with this condition – and in the
process they’ve put it on the map as a medical diagnosis.
The accumulating evidence about cannabinoid hyperemesis
gives us this typical patient profile: a chronic cannabis user under the age of
50 who develops periodic and severe abdominal pain associated with nausea and
vomiting that tends to be worse in the morning and to improve
with hot showers or baths.
For example, in Simonetto’s report (published in February
2012 in Mayo Clinic Proceedings), the
study team reviewed 1,571 charts of patients seen at their institution between
2005 and 2010 and identified 98 that met their criteria for cannabinoid
hyperemesis (long term cannabis users with recurrent vomiting not explained by
any other medical illness). Of these, each one was under the age of 50 and the
vast majority (95% of those for whom data was available) used cannabis at least
twice a week. Of the 57 patients for whom the effect of hot water immersion was
documented, 51 (91%) reported relief. Most patients (86%) also reported
abdominal pain. From these results, the authors have proposed specific criteria
for the diagnosis of cannabinoid hyperemesis – including most of the above
characteristics. As to the cause of the paradoxical vomiting due to
cannabinoids, several theories have been proposed, including the inhibitory
effects of cannabis on peristalsis (the wave-like impulses that propel food
through the intestines). It may also be that chronic use changes the effects of
cannabinoids on THC receptors in the brain. More investigation is needed, however,
and as of now we can only speculate as to why hot showers are such an effective
treatment (it could be because hot water draws blood supply away from the gut
and to the skin). Despite the uncertainty, this new evidence does have a couple
important implications for how we think about cannabinoids.
1) Today’s cannabis is not the same as your father’s
puff the magic dragon. In particular, synthetic and oral cannabinoids can lead
to much higher and prolonged exposure to THC or similar compounds – and this
would, presumably, increase the risk of cannabinoid hyperemesis syndrome. In
particular, “herbal incense” products like Spice and K2 can cause effects –
including prolonged psychosis – that were rarely observed from marijuana alone in
the era of dirt grass and flower power. Thus, while the evidence is
accumulating that cannabinoids may be helpful in the treatment of a number of
uncomfortable medical conditions – including those that cause nausea and
vomiting! – one must be careful with the amount and delivery of the drug. Like
any drug, cannabis is not risk- or side effect- free.
2) If you are a long-term cannabis user
suffering from severe bouts of nausea and vomiting, there may be simple
treatments. First, try a nice, long, hot shower. (I fear I may be setting
myself up for public stoning here, but this may help explain why, for years,
Fairfax’s medical marijuana clinic was located right next to a Frogs Hot Tubs).
But I digress… the second (and
medically advised) treatment for cannabinoid hyperemesis is to stop using
cannabis. In Simonetto’s case series, of those reporting have quit cannabis,
six out of seven (86%) had complete resolution of symptoms.
In medicine, like in life, it is always good to constantly
question and challenge assumptions. The long-standing assumption about cannabis
is that it’s main danger is as a “gateway” drug – and that it is otherwise quite
safe and side effect free. We are starting to learn that this is not exactly
true.
