Weed isn't for everyone. Mind you, for most, the worst that could happen after a couple of tokes is that you'll feel mildly dizzy, throw up a bit on your shoes or potentially be exposed to a Ben Harper singalong.
However, for a very small number of regular users, there's a much more unpleasant consequence to contend with.
Cannabinoid Hyperemesis Syndrome – or "CHS" – is a condition associated with chronic cannabis abuse. Its three primary symptoms are nausea, abdominal pains and cyclical vomiting, an ailment where you retch or throw up far more often than you should (around six to 12 times an hour). So not really the desired effects when you've just spent £10 on a gram of leaves.
The word "cannabinoid" might ring a bell; it's started to crop up a little more since people realised that weed is good for more than enhancing video games and passing the time at school. But if it still means nothing to you, here's a very brief explanation: cannabinoids are a class of chemical compounds, some of which occur naturally in the human body, with the rest found in cannabis and other plants. They're also responsible for all the miracle stories you'll have heard about medicinal marijuana: it's the cannabinoids that help to treat everything from glaucoma to epilepsy.
Unfortunately, cannabinoids don't react so well to CHS sufferers. And because there's little understanding of why this is, the condition is often misdiagnosed. According to the testimonies of patients I read online, this usually leads to numerous visits to the hospital, endless CT scans and all other kinds of tests that, more often than not, paint a picture of a perfectly healthy person who just happens to throw up a lot.
Even more confusingly, cannabis is increasingly being prescribed – or recommended online, if you don't live in a weed-friendly place – as an anti-nausea drug. So how a substance known for its antiemetic properties (stopping you from being sick, essentially) is encouraging exactly what it's supposed to prevent is difficult to explain.
The earliest study into CHS was in 2004, when 19 Australians were identified as having both a cyclical vomiting illness and a fondness for smoking weed as often as they possibly could. Of that 19, only nine patients ended up participating in the study. In seven of these cases, "cessation of cannabis abuse led to cessation of the cyclical vomiting". In other words, when they stopped getting high, they stopped throwing up all the time. Which seems like a pretty black-and-white solution to the problem.
Weirdly, though, there was one anomaly that couldn't be explained: patients had developed a habit of taking scaldingly hot showers or baths, as these apparently helped to relieve their symptoms.
Roughly 30 studies were conducted between 2004 and 2012, with most focusing on singular subjects. Yet, it's still not clear what it is that actually causes CHS (whether a cannabinoid build-up is to blame, or if it has something to do with cannabinoid receptors in the brain) or why the condition has suddenly appeared now, despite the fact that – according to meticulously researched internet chatter – people also definitely smoked cannabis before the year 2004.
In 2012, Dr Douglas A Simonetto conducted the largest study into CHS to date, with 98 patients all meeting the relevant criteria. However, his research only reinforced the idea that CHS is a thing that exists. That, if you smoke too much weed, you might experience nausea and cyclical vomiting (84 also reported abdominal pain), and that if you stop, so too will the symptoms (in the vast majority of cases, at least). He also found that around half the participants mitigated their symptoms by bathing in incredibly hot water.
One of Dr Larry Mellick's videos of a CHS patient
While looking into CHS I found a YouTube account belonging to Dr Larry Mellick, a professor of paediatrics at Georgia Regents University in the United States. For the past year he's been documenting CHS patients, one of whom addresses this compulsive bathing habit in the video above.
"It's not like I needed a shower – it's something I just did without knowing I was doing it," he tells the camera. His sister chips in, saying he would shower four or five times a day in "steaming hot water". Water that she "couldn't stand being in, it was so hot". No explanation is given as to why she was trying to shower with her brother.
The bathing thing appears in almost every report I've read on CHS. In fact, in one case, a patient unknowingly scalded their skin in a bid to ease their symptoms.
It's unclear why the hot showers help, but one certainty – and a positive one at that – is that they can aid medical staff in diagnosing the problem, as well as helping sufferers to understand that they have the condition. "Usually, when one mentions the hot showers bringing relief to their symptoms, it's the first time the patient begins to accept that this might be their diagnosis," Dr Mellick told me.
I spoke to Ben, a student from Bristol, who claimed to have self-diagnosed himself with CHS. After two or three years of smoking "at least seven grams a week", he started to experience the symptoms of CHS in February of last year, "waking up, feeling really sick, having a shower, retching and occasionally puking", as well as suffering abdominal pain.
After a couple of misdiagnoses, Ben realised that he might have been suffering from CHS, so flushed his weed and – dramatically – smashed his bong to pieces. After a week of not smoking, his symptoms started to decrease – a marked improvement on his life before he gave up.
"I was bedridden. I had no energy and my stomach pain was getting worse," he told me. "But I'm now able to move around the house and get on with my day-to-day life."
Of course, we're still no closer to understanding why exactly CHS starts to affect a cannabis user; thanks to years of prohibition, little research has been carried out into the effects of cannabis on the human body's endocannabinoid system. However, speaking to Greg De Hoedt – President of the UK Cannabis Social Clubs – I discussed the possibility that the emergence of the condition has something to do with the fact it's become far easier – if not the norm – to get your hands on super strength skunk.
"Stronger cannabis is available and takes up most of the market," said Greg. "But people don't realise they can get milder strengths. Safer access [to cannabis, coupled] with strain advice is the best reduction for this kind of side effect."
This may be the case for some, but so far the evidence suggests that the best way to cure CHS is to just cut out smoking weed altogether. Of course, that isn't always going to be the easiest thing to convince a patient to do. "I always thought, 'Weed's good; weed's a medicine,'" said Ben. "I thought it was probably helping me in the long run, but it wasn't."
Dr Mellick said something to the same effect. "On occasion, there is a degree of denial, and one has to convince the patient that their presentation is textbook."
Cannabis is becoming more widely accepted, and – in my book, at least – that's not a bad thing at all. As long as you don't end up wasting your life away on hash and Homes Under the Hammer, there's no real reason not to get high every now and again if that's something you like to do.
But, like any drug, cannabis becomes far less enjoyable once you start abusing it. Especially if you manage to wreak havoc with your body's chemistry and find yourself vomiting every time you smoke a spliff.
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