What Is Cannabinoid Hyperemesis Syndrome?

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Cannabinoid hyperemesis syndrome (CHS) is a rare condition involving severe, cyclical episodes of vomiting that are related to the long-term daily use of marijuana. CHS is considered a paradoxical effect, as several active substances in marijuana suppress nausea via their activity in the brain.

The exact reason for the paradox isn’t yet understood, but the key to CHS is believed to involve two factors: marijuana’s interaction with the digestive system plus a lowered sensitivity to the drug’s neurological effects over time.

Marijuana is best known for THC (tetrahydrocannabinol), which is the chemical that makes you high by binding with molecules in your brain. However, the plant contains more than 100 cannabinoids that all have different effects on the body. At least three cannabinoids are known to have an effect on vomiting, including THC, cannabidiol (CBD), and cannabigerol (CBG).

The complex system in your body that interacts with and processes cannabinoids is called the endocannabinoid system. It’s a system based on neurotransmitters, which are chemical messengers in the nervous system. However, that doesn’t mean the system is restricted to your brain. Neurotransmitters are active throughout the body, and their activity is especially high in your digestive system.

CHS was first recognized in 2004. It coincided with a general increase in the use of cannabis, medicinally and recreationally, in the United States.

Cannabinoid Hyperemesis Syndrome Symptoms

The symptoms of cannabinoid hyperemesis syndrome come in three phases, they are:

  1. Prodromal phase
  2. Hyperemetic phase
  3. Recovery phase

The Prodromal Phase

The prodromal phase of an illness is the period of time between the appearance of the first symptoms and when the condition becomes full-blown. In CHS, these early symptoms include nausea, which is usually worst early in the morning, and abdominal pain. This pain is often described as diffuse (spread out) but relatively mild.

Typically, people keep eating normally during this phase, but it's common for people with CHS to develop a fear of vomiting. Some people increase their use of marijuana in response to prodromal symptoms since the drug is known to suppress nausea.

This initial phase often lasts for months, or sometimes years. Symptoms generally aren’t constant but will come and go periodically.

“Cannabinoid” is the term for the active chemicals in the cannabis (marijuana) plant. “Hyper” means excessive and “emesis” is the medical term for throwing up.

Hyperemetic Phase

The hyperemetic phase is when the illness becomes full-blown. The symptoms of this phase include:

  • Chronic nausea
  • Repeated, intense, and incapacitating episodes of throwing up, which can occur several times per hour and without warning
  • Abdominal pain, which is often diffuse but mild
  • Dehydration due to an inability to keep liquids down
  • Weight loss due to eating less

Many people with cannabinoid hyperemesis syndrome find that taking hot baths or showers relieves their nausea. Over time, they may begin to bathe or shower compulsively in an attempt to feel better.

While it’s more of an adaptation than a symptom, this behavior is an important clue when trying to identify the cause of extreme vomiting. Studies have shown this behavior is present in between 90% and 100% of people diagnosed with this condition, and some researchers have proposed it as part of the diagnostic criteria.

The beneficial impact of baths and showers could be due to a known effect of marijuana, which is changing your body’s ability to regulate your temperature. This often results in users getting cold. It’s hypothesized that the hot water alleviates CHS symptoms by correcting this imbalance.

This phase generally goes on until marijuana use is stopped completely. With proper diagnosis and treatment, symptoms may go away within about 48 hours.

Research shows that most people with CHS lose about 11 pounds during the hyperemitic phase.

Recovery Phase

During the recovery phase, symptoms recede, and normal eating resumes. However, using marijuana can cause symptoms to come back. It may be a matter of weeks or even months before marijuana doesn’t trigger symptoms again, and regular use later on could lead to CHS again.

Complications

The primary complications of cannabinoid hyperemesis syndrome are dehydration and low electrolyte levels in your blood, which generally go hand-in-hand and result from throwing up. That can cause symptoms such as:

  • Muscle spasms
  • Muscle weakness
  • Kidney failure
  • Irregular heart rhythms
  • Seizures
  • Shock
  • In extremely rare cases, swelling of the brain called cerebral edema

If you suspect that you’re dehydrated, it’s important for you to get medical attention right away. Sports drinks and other beverages that replace electrolytes can help, but you should also see a doctor to ensure that you properly rehydrate. They can also give you medications that slow or stop the vomiting so you don't continue to lose fluids.

Causes

Because cannabinoid hyperemesis syndrome hasn’t been recognized or researched for very long, and because marijuana has a complex effect on the body, doctors don’t know exactly what causes this condition.

However, it’s believed that marijuana has a contradictory impact that’s to blame. In the brain, pot usually suppresses the systems that cause nausea, while in the digestive system, it makes nausea and vomiting more likely by slowing the rate of food passing out of your stomach and into the small intestine.

Some CHS researchers hypothesize that, during early use, marijuana has a stronger effect on the brain than it does on digestion, so your nausea is lessened. Over time, though, they believe the brain loses some of its sensitivity to the drug while the digestive tract is shown to resist sensitization, so the digestive effects become more and more dominant.

Researchers have not yet determined why some regular marijuana uses end up with CHS while others never do.

Diagnosis

A lot of different conditions cause vomiting, and cannabinoid hyperemesis syndrome is rare. Many doctors may not have even heard of it. That means it can take a long time for you to get the proper diagnosis.

Case reports published in the journal Digestive Diseases and Sciences say that people with CHS had anywhere from three to 11 visits to the emergency room before diagnosis, and one case took nine years to be properly diagnosed.

When you go to a doctor with cyclical vomiting, they have to check you for multiple conditions, especially those that are a serious emergency. They may order multiple tests and scans, including:

  • Blood tests
  • Urine analysis
  • Abdominal X-rays
  • Upper endoscopy (imaging of the stomach and esophagus)
  • Head computerized tomography (CT) scan
  • Abdominal CT scan

Conditions your doctor may need to rule out before diagnosing CHS may include:

None of these tests will definitively diagnose CHS, though. The only way to confirm a suspected diagnosis is to discontinue marijuana and see if the symptoms get better.

Fortunately, that’s something that can be done while you're waiting for test results. If you could have CHS, be sure to bring it up with your doctor, as they may not be familiar with it.

If you suspect CHS, it may be tempting to avoid the doctor and just stop using marijuana to see what happens. However, doing that could delay or prevent the treatment of a more serious condition. It’s safest to make an appointment (or get emergency treatment, if warranted.) Even if quitting makes you feel better, you should still see a doctor.

Treatment

Treating CHS focuses on discontinuing marijuana along with:

  • Anti-vomiting drugs
  • IV fluids for dehydration
  • Pain medication
  • Proton-pump inhibitors, which can lessen inflammation in the stomach
  • Frequent hot baths or showers to temporarily alleviate symptoms
  • Capsaicin cream rubbed on the abdomen

With treatment, symptoms should go away within a day or two. Some people with this condition may need a short hospital stay to stop the vomiting and correct related problems such as dehydration.

If you have trouble stopping or staying away from marijuana, you may want to look into a drug rehabilitation program, private or family therapy, or cognitive behavioral therapy.

A Word From Verywell

You may hesitate to tell your doctor about your marijuana use, especially if it’s illegal where you live, but it’s an important piece of information for them to have—and not just in the case of a cannabinoid-related disorder, but for your overall health and treatment. It could impact your diagnosis and interact negatively with your treatments, all of which could lead to serious health consequences.

Your doctor is legally required to keep the information confidential, thanks to the Health Insurance Portability and Accountability Act (HIPAA) and federal Confidentiality of Alcohol and Drug Abuse Patient Records laws.

Only very specific circumstances allow for disclosure, such as the doctor suspecting children are being abused or neglected because of the drug use. It’s also a serious violation of medical ethics. The conversation may be difficult for you, but it could make a big difference in your healthcare.

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