Cannabinoid hyperemesis syndrome (CHS) is a condition that sometimes develops due to the long term use of marijuana. The syndrome causes repeated and severe vomiting and nausea.

As CHS is a newly described condition, many doctors may find it challenging to diagnose and treat. Researchers have tried to explain what causes CHS, but further study is necessary.

In this article, we describe CHS and discuss the causes, symptoms, diagnosis, and treatment of the condition.

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A person with cannabinoid hyperemesis syndrome may experience morning nausea.

Doctors first described CHS in 2004. The first reports came from doctors treating regular users of marijuana for nausea and vomiting in South Australia.

People with CHS usually have a long history of marijuana use. They also experience episodes of vomiting that return every few weeks or months.

When people with CHS stop using marijuana, their symptoms of nausea and vomiting usually disappear. Nausea and vomiting tend to return if they start using marijuana again.

Doctors also noticed that individuals with CHS would take frequent hot showers and baths. People with the syndrome tended to feel better when bathing.

Many people with CHS go to their doctor or an emergency room (ER) for treatment. However, doctors may find it challenging to diagnose the syndrome because people tend not to report their use of marijuana.

CHS is also underdiagnosed because people sometimes use marijuana to suppress nausea and vomiting. Doctors currently lack knowledge of the condition, and there are no clinical guidelines for its treatment and management.

With the consumption of marijuana increasing due to the legalization of its recreational use in many states, doctors may receive more reports of side effects from marijuana use.

Researchers have several theories on the causes of CHS.

On the basis that only a small number of regular and long term users of marijuana develop CHS, some researchers suggest that genetics might play a role. Other researchers theorize that the effects of marijuana can change with chronic use.

Researchers have identified two receptors called CB1 and CB2 to which marijuana molecules attach. Receptors are specialized cells that respond to specific stimuli or changes in the environment.

CB1 receptors are mostly present in the brain, but they also occur in other organs. Research suggests that CB1 receptors regulate the effects of marijuana on the gastrointestinal tract. Scientists do not know much about the function of the CB2 receptors.

In CHS, receptors that bind to the different components of marijuana can become altered. Some receptors may become more active, while others can shut down. These changes may be responsible for the symptoms of CHS.

The evidence supporting these theories is lacking, though, and further study is necessary to confirm the cause of CHS.

Through different case studies, doctors have identified three stages of CHS: prodromal, hyperemesis, and recovery.

Prodromal stage

During the prodromal stage, people typically experience:

  • morning nausea
  • urges to vomit
  • stomach discomfort

These symptoms may last for months or years. Sometimes, people use marijuana more during this time because the drug is known for its antinausea effects.

Hyperemesis stage

People in the hyperemesis stage will experience intense and persistent nausea and vomiting.

Doctors have also noticed that people in the hyperemesis stage take frequent showers and baths, which seem to relieve nausea.

Recovery stage

The recovery stage can last from days to months. People in the recovery stage often:

  • feel better
  • return to normal eating patterns
  • resume a regular frequency of showering

Clinical guidelines for the diagnosis of CHS do not currently exist. Some researchers have published their findings from their personal experience with the condition in clinical journals.

One group of researchers proposed diagnostic criteria based on three categories of CHS symptoms:

1. Essential criteria to diagnose CHS include:

  • long term marijuana use (more than 1 year)

2. Major features of CHS include:

  • weekly use of marijuana
  • severe, recurring nausea and vomiting that follows a pattern
  • symptoms that resolve when the person stops using marijuana
  • relief of symptoms with hot showers or baths
  • abdominal pain

3. Other features that support a diagnosis of CHS include:

  • age younger than 50 years
  • weight loss of more than 5 kilograms (kg) during the hyperemesis stage
  • morning nausea and vomiting
  • normal bowel habits

Although this information comes from case reports, doctors can use these criteria to diagnose the condition more quickly. Once they have confirmed the diagnosis, treatment can begin.

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Taking pain medications may provide some relief from abdominal discomfort.

Currently, doctors do not have treatment guidelines for the management of CHS. Most of the evidence on effective treatment and management comes from published case reports.

As people with CHS often only consult their doctors during the hyperemesis stage, there is a lack of knowledge regarding the treatment of people during the prodromal stage.

First, doctors treating people with CHS advise them to stop using marijuana. During the hyperemesis stage, doctors focus on preventing dehydration and stopping the symptoms of nausea and vomiting.

Doctors can provide hydration in the form of intravenous (IV) solutions if the person cannot tolerate oral fluids.

Some people with CHS require pain relievers if abdominal pain is present.

To stop symptoms of nausea and vomiting, some doctors may recommend the following:

  • vitamin B-6
  • ondansetron (Zofran)
  • promethazine (Phenergan)
  • metoclopramide (Reglan)
  • dexamethasone (Decadron)
  • famotidine (Pepcid)
  • droperidol (Inapsine)

However, many experts consider these treatments to be ineffective for managing nausea and vomiting in people with CHS.

Lorazepam

In two case reports, doctors used lorazepam (Ativan) to manage CHS-related nausea and vomiting.

One doctor reported using injectable lorazepam to help control nausea and vomiting symptoms in an adult. Within 10 minutes, nausea and vomiting stopped, and the person no longer felt abdominal pain.

Another doctor reported using a combination of injectable lorazepam and promethazine, another antinausea medication.

Results from these case studies suggest that lorazepam might be an effective drug to control symptoms during the hyperemesis stage.

However, doctors exercise caution when prescribing lorazepam because it is a controlled substance with the potential for abuse and addiction. The use of lorazepam for CHS is also off-label, so a person's doctor would need to make them aware of this fact.

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The current lack of knowledge about CHS makes it difficult to diagnose the condition.

Doctors have a lack of knowledge of CHS, and this makes it hard to identify people with the condition. People often remain misdiagnosed for years, which delays treatment.

The only treatments available to people with CHS are those that restore hydration and help control nausea and vomiting.

One possible treatment option involves the use of benzodiazepines, such as lorazepam, to control nausea and vomiting. Benzodiazepines are controlled substances that people must use with caution, particularly those with a history of drug use.

As CHS is a new diagnosis, the manufacturers of these drugs did not design them for treating CHS, but a doctor may opt to prescribe them for this use.

These supportive treatments can help people during the hyperemesis stage of the condition, but recovery depends on the person stopping their use of marijuana. If they continue to use this drug, their symptoms may return.

As the laws regarding the possession and use of marijuana change, CHS may become more prevalent because more people will have legal access to the drug.

CHS is a newly identified condition, so doctors currently know little about it. No clinical guidelines exist, so they must rely on published case reports to treat people with CHS.

Since 2004, doctors have identified key symptoms and characteristics of the condition that can help speed up diagnosis. However, researchers have yet to determine the cause of CHS since it does not affect all users of marijuana.

It is important for people with CHS to stop using marijuana because this will resolve their nausea and vomiting. Preventing dehydration and stopping nausea and vomiting are the treatment goals during the hyperemesis stage of the condition.

Researchers need to study CHS in more detail to make it easier for doctors to recognize and treat the condition. Further studies are also necessary to determine the causes of CHS and its risk factors.