The Syndrome I Didn't Know I Was Missing

Reflections on Cannabis Use, Mental Health, and Cannabinoid Hyperemesis Syndrome

As a psychiatric nurse practitioner, I spend a significant amount of time discussing cannabis use with clients. We talk about why people use it, the benefits they perceive, the potential risks, drug interactions, and the consequences of long-term use. Cannabis conversations have become a routine part of mental health treatment. So imagine my surprise when I encountered a condition directly related to chronic cannabis use that I knew very little about. The reason I came across Cannabinoid Hyperemesis Syndrome (CHS) wasn't through a journal article, conference presentation, or continuing education course.

It was because of a client.

This individual had endured months of symptoms and undergone an extensive medical workup. Specialists were consulted. Tests were ordered. Diagnoses were considered and ruled out. Eventually, they were diagnosed with Cannabinoid Hyperemesis Syndrome. As they shared their experience, I found myself listening not only as their psychiatric provider, but also as a lifelong student of medicine. One of the greatest privileges of this profession is the opportunity to learn from the people we serve. While we bring clinical training and expertise to the therapeutic relationship, our patients bring something equally valuable—their lived experiences. Time and time again, my clients have taught me lessons that no textbook ever could.

This was one of those moments.

As I listened to their story, I realized I knew far less about CHS than I should. That realization led me down a path of learning, conversations with colleagues, and a deeper appreciation for how cannabis can affect both physical and mental health in ways we may not always recognize. My first reaction wasn't curiosity—it was disappointment. Not because I believe I should know everything. Quite the opposite. Psychiatry is a field that constantly reminds me how much there is still to learn. New research emerges every day, and no provider will ever master every aspect of mental health care.

What bothered me was something else.

How could there be a condition associated with long-term cannabis use that produces symptoms many psychiatric providers encounter regularly, yet remains relatively unknown in mental health settings? What really brought this issue home for me was a conversation with a gastroenterology colleague. Over the years, she has evaluated countless patients suffering from chronic nausea, recurrent vomiting, abdominal pain, and unexplained gastrointestinal distress. They undergo extensive workups. Imaging studies are completed. Endoscopies are performed. Laboratory testing is reviewed. Differential diagnoses are carefully considered and ruled out. What struck me during my research was not that CHS is common or easily recognized. In fact, quite the opposite.

CHS is often missed.

The challenge is that its symptoms can stem from a wide variety of medical and psychiatric conditions. Nausea, vomiting, appetite changes, abdominal discomfort, anxiety, sleep disruption, and irritability are symptoms clinicians encounter every day. Depending on the clinical context, these complaints may be attributed to gastrointestinal disorders, medication side effects, anxiety disorders, infections, hormonal changes, substance withdrawal, or numerous other causes.

To make matters even more challenging, CHS does not always present in a predictable manner. Symptoms can range from mild to severe. They may come and go over time, with periods of relative stability interrupted by significant flare-ups. Some individuals experience symptoms while actively using cannabis, while others struggle to recognize a clear pattern at all.

As psychiatric providers, this reality deserves our attention. Many of the symptoms associated with CHS overlap with concerns we routinely assess when initiating medications, adjusting doses, managing side effects, or evaluating cannabis use itself. Because these symptoms are so common and can have many potential causes, it is understandable how CHS can remain overlooked.

This is not an argument that every client experiencing nausea or anxiety has CHS. Rather, it is a reminder that cannabis use should remain part of the conversation when evaluating symptoms that otherwise seem difficult to explain.

For those unfamiliar with CHS, it is a condition associated with chronic, heavy cannabis use that causes recurring episodes of severe nausea, vomiting, and abdominal pain. One of its most unusual—and often overlooked—features is that many individuals experience temporary relief from hot showers or baths. In fact, this behavior has become one of the hallmark clues that points clinicians toward the diagnosis. Another misconception is that symptoms should resolve immediately after cannabis cessation. According to studies, recovery is often much slower than patients expect. Some individuals improve within weeks, while others may require several months of complete abstinence before symptoms significantly improve. Six months is not uncommon, and for some patients, recovery may take even longer.

What remains consistent is that abstinence is currently considered the only definitive treatment.

The connection between CHS and mental health becomes even more important when we consider why many individuals use cannabis in the first place. In psychiatric practice, people often report using cannabis to manage anxiety, depression, PTSD, insomnia, or chronic stress. While some experience short-term relief, the long-term relationship between cannabis and mental health is far more complicated than many people realize.

Research has increasingly linked heavy cannabis use with higher rates of depression, bipolar disorder, psychosis, and cannabis use disorder. Among individuals with depression, cannabis use has also been associated with increased suicidal thoughts and behaviors. For adolescents and young adults, particularly those using high-potency THC products, the risk of developing psychosis appears significantly higher.

Researchers are still working to fully understand why CHS occurs. Current evidence suggests that chronic cannabis exposure may dysregulate the endocannabinoid system—a complex network involved in regulating mood, appetite, pain, stress responses, and nausea. Because this system exists throughout both the brain and gastrointestinal tract, disruptions may affect multiple body systems simultaneously.

Several theories have been proposed to explain CHS. One theory suggests that chronic stimulation of cannabinoid receptors alters the normal brain-gut communication pathways involved in nausea and vomiting. Another proposes that prolonged exposure changes how the body processes cannabinoids over time. While the exact mechanism remains unclear, the result can be a paradoxical situation in which a substance commonly used to relieve nausea ultimately contributes to it.

What fascinates me most about CHS is not simply the syndrome itself, but what it teaches us about the interconnectedness of the human body. We often separate mental health from physical health, yet conditions like CHS remind us that the brain and body are in constant communication. What affects the brain can affect the gut. What affects the gut can affect mental health.

As clinicians, we owe it to our clients to remain curious. As clients we owe it to ourselves to have honest conversations about all aspects of our health—including cannabis use. Perhaps the greatest lesson CHS taught me was not learning about a new syndrome. It was being reminded that some of the most important discoveries in medicine are the things we didn't know to look for in the first place.

And for that lesson, I have a client to thank.

This article is intended for educational purposes only and should not be considered medical advice. If you have concerns about your cannabis use or your health, please speak with a qualified healthcare professional.