The naturally occurring and widely used substance has some people questioning whether or not it has any link to the syndrome

Ever wonder why insects and pests don’t devour outdoor cannabis crops?

Much like fruits and vegetables, cannabis plants can benefit from using pesticides to repel and mitigate non-beneficial pests. The pesticide of choice for some cannabis growers is neem oil, a naturally occurring and sometimes controversial pesticide found in the seeds of the neem tree.

The controversy stems from the claim that azadirachtin, the most active pest-repelling component in neem oil, causes cannabinoid hyperemesis syndrome, or CHS. Despite there being no registered, neem oil-based pest control products approved by Health Canada (aside from TreeAzin, which is used to protect the emerald ash borer tree), it remains popular among cannabis home growers.

Opposing viewpoints on neem oil continue to surface, so let’s explore the arguments on both sides.

Some attribute CHS to neem oil poisoning

Factually, CHS is characterized by chronic cannabis use and cyclic episodes of nausea and vomiting. To date, studies show the syndrome is associated with long-term cannabis use and, in some users, is triggered by overconsumption.

Discussions around whether or not CHS is directly linked to neem oil, however, have inspired considerably more opinion.

Some believe that CHS is actually just a decoy for azadirachtin toxicity or neem oil poisoning, which is marked by intense nausea, cyclic vomiting, abdominal pain, diarrhea, muscle tension, fatigue and dehydration.

Cannabis Hyperemesis Syndrome has been shown to be a farce, It is actually caused by use of insecticides derived from Neem oil that are used to deal with spidermite on indoor grows. This builds up in the body over time and causes the symptoms. Been known for a number of years now — Matt Pallett (@nlightn4) June 3, 2019

In response to The GrowthOp’s recent article about CHS, one reader says:

“Your article about cannabis hyperemesis syndrome is missing a very key point. Neem oil is used in the cannabis industry as an ‘organic pesticide’, and this syndrome [CHS] is identical to the exposure to neem oil. By consuming large doses of cannabis, the patient is unwittingly absorbing trace amounts of neem oil and having the typical reaction.”

One steemit user even goes as far as to call CHS a “myth,” arguing that the “nonsensical syndrome” has the same symptoms as azadirachtin toxicity.

It is clear from the post’s comments that this user is not alone. Commenters cite their scepticism of neem oil and use the aforementioned post to justify their suspicion.

The idea is that the build-up of residual azadirachtin in heavy smokers might cause CHS—but correlation doesn’t necessarily mean causation. So what does the science say?

Do symptoms suggest a neem oil, CHS link?

Dr. Ian Mitchell, clinical associate professor of emergency medicine at the University of British Columbia, explains that CHS symptoms are distinct from those of neem oil poisoning.

Neem oil as cause for #Cannabis Hyperemesis Syndrome? Don't think so for a couple of reasons – more in this recent review. https://t.co/LRSFlCVjms @LadyLeafLife @tomfolanmd @hartsteinfeld — Ian Mitchell (@travels2little) April 13, 2019

“There have been reports of neem oil poisoning causing nausea and vomiting, so it just seems like a potential suspect, but it’s only a weak linkage,” Dr. Mitchell says. “Sure, it [neem oil poisoning] causes nausea and vomiting, but there is no record that shows patients wanting to take hot showers.”

Taking a hot shower, Dr. Mitchell explains, is a common form of relief for CHS patients that is not present in those with neem oil poisoning. “Overdoses of neem oil cause brain and nerve damage, and that’s not what we see in CHS patients,” he adds.

Cannabis medicine consultant Dr. Tom Folan, founder and CEO of SolaceMD Group, points out another differentiator. “A 2013 study shows CHS in patients taking synthetic cannabinoids. And those synthetic cannabinoids are found nowhere near neem oil,” Dr. Folan says. “If neem oil is causing CHS, then why would synthetic cannabinoids also precipitate CHS?” he asks.

Dr. Folan says that beyond being used as a cannabis pesticide, neem oil is actually quite prevalent in household products. “Neem oil is also used in a range of different things, such as toothpaste, soaps and skincare. Far from it being toxic, it’s actually quite good for you,” he says.

So what causes CHS symptoms, then?

Both Dr. Folan and Dr. Mitchell agree CHS symptoms are likely caused by the deregulation of the transient receptor potential vanilloid 1 or TRPV1 (capsaicin) receptor. This receptor, Dr. Folan says, only responds to three things: heat in the form of hot showers, cannabis and hot peppers.

“A CHS study that came out in 2018 shows the inactivation of the TRPV1 receptor and that’s a game-changer in terms of understanding CHS,” he suggests. “There’s a lot we don’t know, but there’s a good forming hypothesis for how chronic stimulation of these receptors causes deregulation.”

The 2018 study notes that overconsumption of cannabis can inactivate the TRPV1 receptor, which, in turn, causes nausea and alters gastric mobility.

CHS patients often treat their symptoms with hot showers, eating hot peppers or rubbing hot pepper paste on their bodies to reactivate the TRPV1 receptor and normalize gastric mobility.

More and better research is needed to better understand the effects of cannabis, Dr. Folan says. He cautions that “the dose makes the poison,” and overconsumption can be costly.

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