Evidence based

What Is Cannabinoid Hyperemesis Syndrome (CHS)?

Cannabinoid Hyperemesis Syndrome (CHS) is characterized by excessive vomiting and abdominal pain induced by long-term, frequent use of marijuana.

Article By
Justin Cooke , last updated on September 3, 2021

One of the most common reasons people reach for cannabis products is to alleviate symptoms of pain or nausea.

Ironically, in a very small percentage of cannabis users, a condition called cannabinoid hyperemesis syndrome (CHS) can lead to the exact opposite. This condition causes sufferers to experience violent bouts of vomiting, ongoing nausea, and abdominal pain.

What causes CHS? What can I do to prevent or reverse it?

What is Cannabinoid Hyperemesis Syndrome?

Cannabinoid hyperemesis syndrome (CHS) is a rare condition that occurs in some patients who use cannabis products (especially marijuana) regularly over several months or years.

Let’s break this term down into its parts, so we know what we’re dealing with here:

  • Cannabinoid = the active set of ingredients in the cannabis plant
  • Hyperemesis = excessive nausea and vomiting (hyper = excess, emesis = vomiting)
  • Syndrome = a group of symptoms that occur together but aren’t categorized as a disease

The exact cause of this condition remains unknown — which is why it’s considered a syndrome rather than a disease.

What we do know is that the condition primarily affects people who use marijuana products regularly over long periods of time. One study found that only 3% of people who use marijuana infrequently suffer from symptoms that could classify as CHS — the other 97% were considered “frequent users” [2].

This same study found that 93% of patients who stopped using cannabis saw their symptoms resolve within a couple of days.

The majority of patients also reported hot showers were the most effective way of alleviating symptoms of the condition (temporarily).

There are three main phases of CHS, each of which have their own characteristic symptoms:

1. Prodromal Phase

This is the first phase, which can last for several months or even years before transitioning into the next phase.

Most people will experience nausea early in the morning, along with abdominal pain.

2. Hyperemetic Phase

This is the phase where people usually seek medical assistance and are diagnosed with CHS.

Symptoms include:

  • Ongoing or repetitive bouts of nausea
  • Vomiting
  • Abdominal pain
  • Dehydration
  • Poor appetite or aversion to food

The vomiting during this stage can be severe and ongoing — sometimes leading patients to seek emergency medical care.

Excessive vomiting and lack of appetite can cause dehydration, electrolyte imbalance, anxiety, insomnia, and loss of weight. It can be dangerous if left untreated for too long.

3. Recovery Phase

Once marijuana is stopped, it can take a few days to transition from the hyperemetic phase to the recovery phase. When this happens, nausea and vomiting symptoms start to gradually disappear, and appetite comes back.

This phase can take several days or weeks before returning to normal.

What Are the Symptoms of CHS?

The primary symptoms of CHS are abdominal pain and vomiting. People suffering from this condition experience repetitive, often severe bouts of vomiting, followed by periods of no symptoms whatsoever.

Symptoms include:

  • Nausea (ongoing or repetitive)
  • Vomiting (anywhere from mild to intense)
  • Abdominal pain (usually in the middle of the belly)
  • Diarrhea
  • Excessive thirst
  • Sweating
  • Anxiety
  • Dry mouth

There are a lot of different health conditions that share similar symptoms, so it’s important you visit a doctor for an examination if you’ve been vomiting for more than three days.

If no treatment is given, and sufferers continue to use marijuana despite the symptoms, they can evolve into much more severe side-effects. The main cause of these more severe effects stem from dehydration or electrolyte imbalance due to excessive vomiting.

Side effects of dehydration include:

  • Seizures
  • Kidney failure
  • Irregular heartbeat
  • Shock
  • Brain swelling
  • Muscle weakness

Other symptoms may include tooth decay (caused by the degradation of the enamel from stomach acid), esophagitis, or Mallory-Weiss syndrome.

How Common is CHS?

According to the current data, CHS is very rare in people who use cannabis infrequently (a few times per year) and rare in people who use cannabis only once or twice per month.

One study examined emergency-room visits to identify the prevalence of CHS [3]. They examined 2127 patients who visited the ER at a hospital in New York. Only 155 of these patients reported using marijuana more than 20 times per month. Out of this study group, 33% have experienced symptoms in the past that could be related to CHS.

The problem with this study is that the criteria they used to determine how common CHS may be infrequent marijuana users was simply “nausea relieved by hot showers.” While it’s true that hot showers often relieve nausea due to CHS, they can also help with other causes for nausea.

What Causes CHS?

There are three main theories for what might cause CHS:

1. Hypothalamic Theory

The first theory is that frequent exposure to cannabinoids like THC (tetrahydrocannabinol) causes a shift in the balance of ECS activity in the hypothalamus. The hypothalamus is the region of the brain responsible for regulating stress and temperature regulation.

When these receptors become dysfunctional (particularly the CB1 receptors), it could cause a change in the thermoregulatory set-point for body temperature and affect the nearby nausea center in the brain. This would result in a reduced body temperature and could explain why taking a hot shower is so effective for mitigating symptoms.

CBD has been shown to increase the expression of CB1 receptors in this part of the brain, which could mean this cannabinoid is a contributing factor to the disorder. It’s THC that actually activates these receptors, however.

2. Cannabinoid Build-Up Theory

The second theory suggests the symptoms of CHS are caused by a toxic dose of cannabinoids.

When we take any substance into the body, it needs to be cleared by the liver and the kidneys. If we continually take more of the substance before it’s completely eliminated from the body, it can start to buildup in the bloodstream.

We may not notice the increased concentration of cannabinoids for a long time, but eventually, levels will reach a toxic threshold — which may cause the symptoms associated with CHS.

Additionally, cannabinoids are stored in fat. Once we start losing weight due to frequent vomiting caused by CHS, the loss of fat will release even more cannabinoids into the body — causing the condition to worsen.

3. TRPV1 Theory

The final theory involves a separate type of receptors many cannabinoids interact with called TRPV1 or the vanilloid receptors.

These receptors are responsible for the “hot” sensation experienced when eating spicy foods, and they play a role in the transmission of pain, movement of the gastrointestinal system, and temperature regulation.

Some cannabinoids have been shown to reduce the sensitivity of the TRPV1 receptors. So it’s believed that frequent exposure to these cannabinoids may cause downregulation of the TRPV1 receptors, leading to the symptoms associated with the condition.

This explains the compulsive need to take hot showers to normalize TRPV1 activity and alleviate symptoms.

It could also explain why other TRPV1 agonists, such as capsaicin ointments, are so reliable for providing relief from the condition as well.

Which Cannabinoids Contribute to CHS?

It’s unclear which cannabinoids directly cause the symptoms associated with CHS. Current evidence points the finger at THC — which is the primary activator of the endocannabinoid receptors.

However, other cannabinoids may be involved as well:

Can CBD Cause CHS?

The primary cause of CHS is THC found exclusively in marijuana products.

It’s unclear whether CBD (cannabidiol) can cause CHS too, but early evidence suggests it may contribute to existing CHS symptoms. CBD has been shown to enhance the expression of CB1 receptors in the hypothalamus and amplifies the hypothermic effects caused by THC [5]. This effect could increase the progression of CHS through the hypothalamus theory highlighted above.

Additional studies have shown that lower doses of CBD are antiemetic, but higher doses can actually cause vomiting [6]. This would support the idea that CBD can cause CHS through the cannabinoid buildup theory mentioned above.

This means if you’re experiencing CHS, you should avoid taking any and all cannabis products — including non-psychoactive hemp supplements.

Researchers are still seeking to understand which cannabinoids can cause the condition and which ones can’t.

Can Delta 8 THC Cause CHS?

There are two forms of THC — delta 9 THC and delta 8 THC.

The most common form, by far, is the delta 9 isomer — which has already been confirmed to be one of the primary causes of CHS.

So what about the less abundant delta 8 THC isomer?

There’s virtually no research on how delta 8 THC may affect people with CHS, and there aren’t enough users to find a pattern in people with symptoms of CHS.

With that said, delta 8 THC is still THC — it affects the same receptors, and despite having some differences in how it affects the body, it still pushes the same receptors and causes the same effects. It’s very likely that delta 8 THC has the same or similar effects on the ECS that cause the condition of CHS.

Can CBG Cause CHS?

CBG (cannabigerol) has been shown to reverse some of the anti-nausea effects of THC as the CB1 receptor sites [4]. Some preliminary studies suggest this cannabinoid may be a contributing factor in the pathophysiology of CHS.

How is CHS Diagnosed?

CHS is a syndrome — which means it’s a set of symptoms that often accompany each other but may not share the same underlying cause.

It’s much harder to diagnose a syndrome than a disease, which has a specific, identifiable cause.

As a result, diagnosing CHS is done by ruling out other potential causes — rather than by testing for the disorder itself.

This condition is still not well understood and was only first identified in 2004 [1]. As cannabis becomes legal in more parts of the world, rates of this condition are increasing. CHS currently accounts for around 6% of emergency room visits for vomiting. As a result, the medical community is getting much better at diagnosing it. 

Doctors may request the following tests to rule out other potential causes:

  • Blood tests — to check for anemia, infection, or leukemia
  • Electrolyte test — to check for signs of dehydration or hyperkalemia
  • Liver function tests — to check for signs of liver disease
  • Pregnancy test — to assess the potential for symptoms caused by morning sickness
  • Urine tests — to check for signs of drug use, infection, or kidney disease
  • X-rays or ultrasound of the abdomen — to check for physical causes of pain & vomiting
  • Head CT scan or fMRI — to check for other neurological disorders that may explain symptoms

They’ll also want to know about the last time you used marijuana or other cannabis products (including delta 8 THC or CBD) and how often and for how long you’ve used them. They may also ask about the dose or request you bring packaging for the products you’re using in the clinic so they can take a look.

They will also ask about other medications, family history, and whether or not you’ve been sexually active.

How is CHS Treated?

The best treatment for this condition is to stop using any and all marijuana products.

Researchers are still trying to understand this condition in more detail, but from the data we have available right now, it appears this condition is permanent. Meaning that patients who suffer from CHS will experience the same symptoms all over again if they use marijuana products again — even after taking an extended break from marijuana.

The rest of the treatment involves managing symptoms and preventing the more dangerous side effects associated with dehydration and electrolyte imbalance that can result from frequent vomiting.

Treatment for CHS may include:

  • IV fluid (for dehydration)
  • Antiemetic medications (medications that prevent vomiting)
  • Pain medications
  • Proton pump inhibitors
  • Frequent hot showers
  • Anti-anxiety medications (such as benzodiazepines)
  • Herbal medicines (such as ginger or topical cayenne ointments)
  • Dopamine antagonists
  • Stopping all opioid medications

Cannabinoids & The Endocannabinoid System

There are many active ingredients in the cannabis plant. The primary constituents are THC (tetrahydrocannabinol) and CBD (cannabidiol).

Both of these active ingredients work through a series of receptors known collectively as the endocannabinoid system (ECS).

The ECS is responsible for regulating neurological, gastrointestinal, renal, cardiovascular, and immune function. It’s intimately involved in monitoring and maintaining a balance of these critical systems.

Every living organism on earth has an ECS. Hormone-like compounds called endocannabinoids are made by the body to transmit messages between the ECS receptors. We need this system to survive — without it, we lose our ability to maintain balance (homeostasis).

Cannabinoids from the cannabis plant, such as THC and CBD, have a similar shape and structure to our endocannabinoids. This allows them to interact with the ECS by activating or altering the receptors. This is what gives cannabis its health-promoting benefits.

CBD, for example, increases the activity of the ECS in the brain — which results in an inhibition of pain, inhibition of nausea, and reduced electrical activity associated with anxiety.

THC also increases ECS activity in the brain, but in a different way. It stimulates the CB1 endocannabinoid receptors, which in turn control serotonin. The shift in serotonin levels is what makes users feel high when they use marijuana products.

Summary: What is CHS?

CHS stands for cannabinoid hyperemesis syndrome. It’s sometimes referred to as cannabis hyperemesis syndrome — both of these terms mean the same thing. 

Over time, the body becomes resistant to the effects of the active ingredients in the plant. When marijuana is used, it leads to a dramatic increase in nausea and vomiting and can cause abdominal pain, dehydration, dizziness, and a variety of other symptoms.

The only known treatment for CHS is to stop using marijuana. Upon stopping, symptoms usually go away within two days but can take several months in some people.

This condition is still very poorly understood, and we still don’t know exactly what causes it or which cannabinoids are involved.

References Cited In This Article

  1. Chu, F., & Cascella, M. (2019). Cannabinoid hyperemesis syndrome.
  2. Sorensen, C. J., DeSanto, K., Borgelt, L., Phillips, K. T., & Monte, A. A. (2017). Cannabinoid hyperemesis syndrome: diagnosis, pathophysiology, and treatment—a systematic review. Journal of Medical Toxicology, 13(1), 71-87.
  3. Habboushe, J., Rubin, A., Liu, H., & Hoffman, R. S. (2018). The prevalence of cannabinoid hyperemesis syndrome among regular marijuana smokers in an urban public hospital. Basic & clinical pharmacology & toxicology, 122(6), 660-662.
  4. Rock, E. M., Goodwin, J. M., Limebeer, C. L., Breuer, A., Pertwee, R. G., Mechoulam, R., & Parker, L. A. (2011). Interaction between non-psychotropic cannabinoids in marihuana: effect of cannabigerol (CBG) on the anti-nausea or antiemetic effects of cannabidiol (CBD) in rats and shrews. Psychopharmacology, 215(3), 505-512.
  5. Hayakawa, K., Mishima, K., Hazekawa, M., Sano, K., Irie, K., Orito, K., … & Fujiwara, M. (2008). Cannabidiol potentiates pharmacological effects of Δ9-tetrahydrocannabinol via CB1 receptor-dependent mechanism. Brain Research, 1188, 157-164.
  6. Parker, L. A., Kwiatkowska, M., Burton, P., & Mechoulam, R. (2004). Effect of cannabinoids on lithium-induced vomiting in the Suncus murinus (house musk shrew). Psychopharmacology, 171(2), 156-161.

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