What is Cannabinoid Hyperemesis Syndrome?

Cannabinoid Hyperemesis Syndrome (CHS) is affecting cannabis consumers at a growing rate. But what exactly is it, and how can it be treated?

CHS is a rare condition characterised by repeated and extreme bouts of vomiting, which in some cases can lead to severe dehydration.

Not a great deal is known about the condition, which was only first described in 2004 and is reported to affect only 0.1 per cent of people, but it is believed that it is most common in young adult males.

Research into the condition is minimal, however one pattern in CHS cases is recreational cannabis use, taking place on a regular basis – symptoms usually begin after chronic daily intake for approximately five years. But while usage has generally been described as ‘heavy’, it can be difficult to quantify what is considered a high dose.

In terms of causes, initial studies suggest that active substances in cannabis and anti-nausea effects are the main triggers of CHS.

THC, the main ingredient in cannabis, has anti-sickness effects and is why the drug is regularly prescribed for nausea caused by chemotherapy. However, if consumed over a long period of time, cannabis seems to have the opposite effect on the digestive system and make you more likely to feel and be sick.

Research by Gajendran, Sifuentes, Bashashati and McCallum involved a review of 18 patients who met the criteria for CHS, and comparison with 27 patients with ‘classic’ CVS (Cylic Vomiting Syndrome).

The patients answered a questionnaire addressing onset of symptoms, treatment, quality of life, employment, and ability to return to social activities. These patients were managed personally with long-term follow-up by one of the authors at Texas Tech University Health Science Center in El Paso.

Prior to CHS diagnosis, 39 percent (7/18) of patients had symptoms between 4 and 10 years, and 11 percent of patients (2/18) had symptoms for more than 10 years. When patients with CHS were compared with the patients with classic ‘CVS’, there was no significant difference in the baseline demographics and disease characteristics apart from the chronic daily use of cannabis.

There are several methods currently being tested to manage CHS, such as conventional antiemetics which are commonly used in acute care settings. However, a systematic review by Richards et al concluded that conventional antiemetics alone are frequently ineffective, while intravenous benzodiazepines have better efficacy.

Benzodiazepines such as lorazepam have been successfully, with lorazepam typically prescribed as oral tablets for patients. Benzodiazepines are gamma-aminobutyric acid (GABA) agonists with antiemetic effects and also have anxiolytic and sedative properties, which are helpful in the setting of the abnormal sympathetic nervous system response to stress—the sedation results in no vomiting and loss or no awareness of ongoing pain.

But unfortunately for medicinal users, NHS guidance states that in order to fully recover, you will need to stop consuming cannabis all together.

With research still emerging on the topic, only time will tell exactly how – if at all – CHS can be effectively managed.