Cannabis Hyperemesis Syndrome: THC as the cause, CBD as an alternative?

With the legalization of cannabis in 2024, public interest in diseases associated with cannabis use is also increasing. This is not necessarily due to a significant increase in people consuming cannabis. It's also possible that legalization (partial or full) allows for more open discussion about consumption and facilitates more research. Diseases that were long a fringe topic or rarely named are now coming into sharper focus.

One such condition is Cannabis Hyperemesis Syndrome/Cannabinoid Hyperemesis Syndrome, or CHS for short, which is primarily characterized by attacks of nausea and vomiting. Even people who consume the non-psychoactive cannabinoid CBD are unsettled. Can such and similar conditions associated with cannabis use also occur with CBD consumption? What do I need to pay attention to in order to prevent this? Are there specific risk groups?

We'll take a detailed look at the disease CHS, describe who can get it and why, and assess how likely CHS is for CBD users. (Spoiler: The risk of CHS with CBD is very low.)

Cannabis hyperemesis syndrome describes a gastrointestinal disorder directly related to chronic cannabis use. It was first medically described in 2004, although the disease naturally existed before that. (1) The diagnosis is not made through a single test, but by analyzing a combination of symptoms, the patient's individual consumption history, and the exclusion of other causes.

Typical for CHS is a cyclical course. In an early phase, affected individuals experience diffuse symptoms such as morning nausea, pressure/pain in the upper abdomen, or loss of appetite. This phase can last for months or even years, often without patients seeking medical attention or receiving a diagnosis.

Only in the acute phase does severe vomiting occur, often several times a day. The symptoms are often so severe that some affected individuals end up in the emergency room. Conventional anti-nausea medications usually do not provide reliable relief. The vomiting attacks can last for several days and often occur in cycles, between which affected individuals feel relatively normal. Accompanying symptoms may include abdominal pain, weakness, dizziness, and a strong feeling of illness.

Particularly striking: patients have a strong urge to shower or bathe in very hot water. The heat seems to temporarily relieve symptoms for many people. It is assumed that the temperature stimuli affect the central nervous system, thus providing short-term relief. In fact, the urge for hot baths/showers is so characteristic that it is one of the central diagnostic criteria for doctors to identify CHS.

The danger of Cannabis Hyperemesis Syndrome is unfortunately still often underestimated. While the disease itself is not immediately fatal, the consequences of frequent vomiting can be critical. The body loses fluids and electrolytes, especially potassium, which is necessary for healthy heart function, over a long period. Patients consume less food overall or vomit it up again, resulting in sometimes very significant weight loss.

Acute kidney failure due to severe fluid loss is also possible. Additionally, severe vomiting can lead to esophageal injuries, which in turn can carry further risks.

Particularly problematic: CHS is often diagnosed very late. Many sufferers experience a veritable odyssey through doctor's offices and countless examinations without the true cause being recognized. There are reports that affected individuals were dismissed as "potheads" and their symptoms ignored. Others may have been prescribed cannabis by their doctor themselves - e.g. for treating nausea during chemotherapy - so the connection with the symptoms is only recognized late.

Such a delay not only prolongs unnecessary suffering for patients, with potential physical and psychological consequences such as depression or social isolation. It can also lead to the syndrome becoming chronic and recurring over many years.

Currently, research on CHS is still rather limited, with systematic studies only beginning a few decades ago. Therefore, little can be said about the frequency of CHS. Current studies suggest that only a small percentage of all cannabis users are affected.

Estimates vary between one and six percent, depending on the study, for individuals who consume cannabis daily or almost daily over several years. Occasional use currently appears to pose hardly any relevant risk. (2)

Particularly striking: it seems to matter little how much cannabis a person consumes. What is primarily relevant is continuous consumption. Individual factors such as genetic predisposition, psychological disposition, but possibly also the quality of the cannabis consumed, also seem to play a role.

Some authors suspect that the risk may increase with the rising potency of modern cannabis products. (3) The THC content of currently available strains is sometimes significantly higher than that of older products. Since the primary cause of CHS is seen in the interaction of THC with cannabinoid receptors, this could indeed increase the danger. However, large-scale studies on this are still lacking.

With the increasing potency of modern cannabis products, there could be an increase in risk. The THC content of many currently available strains is significantly higher than it was decades ago. Since THC is considered the main cause of CHS, it is plausible that highly potent products increase the risk, even though definitive long-term data on this is not yet available.

The course of Cannabinoid Hyperemesis Syndrome (CHS) initially appears paradoxical. This is because cannabis is now considered a particularly effective remedy for nausea and vomiting, e.g., during chemotherapy.

The main reason for this is the psychoactive cannabinoid THC. It interacts with the endocannabinoid system in the body, which plays a central role in regulating nausea, appetite, pain perception, sleep, and stress, among other things. In the short term, THC therefore acts as an "antiemetic" (emesis = vomiting). In the long term, however, some people seem to experience dysregulation of this system.

Medical professionals suspect that CHS is triggered by the repeated activation of cannabinoid receptors in the brain and digestive tract, which in turn causes a paradoxical reaction. Instead of suppressing nausea, it is now amplified. Why this happens and why only some consumers are affected is not yet clear. Genetic differences in receptor structure or in the metabolism of THC could play a role.

A particularly interesting aspect (also for the classification of the disease): In the vast majority of affected individuals, symptoms disappear with complete cannabis abstinence. If patients resume consumption, the symptoms often return.

While in German, it's usually referred to as Cannabis Hyperemesis Syndrome, English medical literature often uses Cannabinoid Hyperemesis Syndrome(e). This causes uncertainty for many users of non-psychoactive cannabinoids like CBD (Cannabidiol). Can I get CHS from cannabidiol too?

Here, we can give the all-clear—at least according to current research. Although CBD also acts on the endocannabinoid system, it does so very differently from THC. While THC directly binds to the ECS receptors, CBD only modulates them. Pure CBD, therefore, cannot trigger CHS.

In fact, CBD could be a good alternative to THC/medical cannabis, as it can also have antiemetic effects itself—without the risk of a paradoxical reaction as with THC-containing products. However, there is a lack of comprehensive human studies on pure CBD products for nausea and vomiting.

Nevertheless, there are reports from affected individuals who claim to have experienced CHS symptoms after consuming CBD-containing products. Here, a distinction must first be made: Yes, pure CBD and full-spectrum oils can lead to mild digestive problems, especially at higher doses. However, these disappear when the dose is reduced. Also, these primarily involve diarrhea and constipation, less so vomiting. The urge for hot showers is also not part of the symptomatology here.

If "true" CHS symptoms occur after consuming CBD-containing products, it was not pure CBD. Some full-spectrum oils and other cannabis preparations sometimes contain quite high levels of THC—up to 0.3% in over-the-counter products in Germany. In sensitive individuals or those who have previously suffered from CHS, even this small amount of THC could theoretically trigger a new CHS episode.

You can play it safe by only consuming CBD products with minimal THC content or CBD isolates. All Hanfgeflüster products contain less than 0.1% THC and are therefore safe even for sensitive individuals. The ingredients are regularly certified in independent laboratory analyses, so you can get a comprehensive picture for yourself.

To give you a good overview, we have presented the risk of developing CHS here - once for cannabis use, once for the use of CBD full-spectrum oils, and once for CBD isolates.

Although rare, Cannabinoid Hyperemesis Syndrome is not harmless. The condition causes considerable suffering for patients and should be taken seriously by doctors. The most important finding of research in recent years: the central trigger of the syndrome is THC, and symptoms disappear in most cases with consistent cannabis abstinence.

For people who consume CBD, there is little cause for concern according to current knowledge. Pure CBD cannot trigger CHS and differs significantly from THC pharmacologically. However, the quality of the products used is crucial. CBD full-spectrum preparations can contain small amounts of THC, which could theoretically trigger symptoms in very sensitive individuals or those with a history of CHS. If you want to be on the safe side, only use tested products with a minimal THC content.

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