CHS, or cannabinoid hyperemesis syndrome, is a condition where long-term, heavy cannabis use triggers cycles of severe nausea, vomiting, and abdominal pain. It affects roughly 18% of daily cannabis users, which translates to an estimated 7.2 million adults in the United States alone. The condition is paradoxical: cannabis is widely known to reduce nausea, but in heavy users it can flip and do the opposite.
Why Cannabis Starts Causing Nausea Instead of Relieving It
Your body has its own system for managing nausea and appetite, and cannabis plugs directly into it. When you use cannabis occasionally, THC activates receptors in the brain that suppress nausea and boost appetite. But with chronic, heavy use, those same receptors become overstimulated and start to malfunction. The body’s built-in nausea controls essentially get thrown off balance.
THC also gets stored in fat cells. When your body is under stress or you haven’t eaten, it breaks down fat for energy and releases that stored THC back into the bloodstream. At high enough concentrations, THC switches from anti-nausea to pro-nausea. This is why episodes can seem to come out of nowhere, even on days when you haven’t used much cannabis. The higher the potency of what you’ve been using and the longer you’ve been using it, the more THC has accumulated in your body’s fat stores.
The Three Phases of CHS
CHS typically moves through three distinct stages that cycle repeatedly as long as cannabis use continues.
Prodromal Phase
This is the early warning stage. You wake up feeling nauseous, especially in the morning, with vague abdominal discomfort but no actual vomiting. Many people don’t connect these symptoms to cannabis at this point, and some even increase their use thinking it will help settle their stomach. This phase can last weeks or months.
Hyperemetic Phase
This is the crisis stage that sends people to the emergency room. The nausea becomes relentless and the vomiting is intense, often described as “intractable,” meaning standard anti-nausea medications don’t work. Mild, diffuse abdominal pain is common. People in this phase often discover on their own that extremely hot showers or baths provide temporary relief, and they may spend hours in the shower compulsively. This learned behavior is one of the hallmark signs of CHS and helps distinguish it from other conditions.
Recovery Phase
Once the vomiting episode passes, symptoms ease and the compulsive bathing stops. This phase can last weeks to months, and during it you may feel completely fine. But if cannabis use continues, the cycle eventually restarts with another hyperemetic episode.
Who Gets CHS
CHS typically develops after years of using cannabis multiple times per week. It doesn’t happen to occasional users. The condition is more common among younger adults, women, people with lower incomes, and those who report other cannabis-related problems. Notably, only about 11.5% of people experiencing CHS symptoms have actually received a formal diagnosis from a medical provider, suggesting many people are living with it without knowing what it is.
Higher-potency cannabis products, which have become increasingly common in legal markets, may accelerate the process since they deliver more THC per use and lead to greater accumulation in fat tissue.
Why Hot Showers Help (and How Capsaicin Works the Same Way)
One of the strangest features of CHS is that scalding hot showers bring dramatic, temporary relief. This isn’t just a comfort thing. Your body has a type of receptor that responds to both high temperatures and capsaicin (the compound that makes chili peppers hot). These receptors play a role in pain signaling and nausea. When hot water above about 109°F activates them, it triggers a cascade of chemical signals that temporarily suppress the vomiting response.
This is also why capsaicin cream, rubbed on the abdomen, has been used successfully as a treatment during acute episodes. It activates the same receptors that hot water does, providing relief through the same pathway without the risk of spending hours in a scalding shower. The cream causes a temporary burning or stinging sensation on the skin, but for people in the middle of a severe episode, the trade-off is worth it.
Serious Complications
CHS is more than just miserable. The combination of violent, prolonged vomiting and hours spent in hot showers creates a perfect setup for dangerous dehydration. This can progress to kidney failure, a complication serious enough that researchers have proposed giving it its own name. Electrolyte imbalances from repeated vomiting can also become dangerous, particularly for the heart. People who delay seeking treatment during severe episodes are at the highest risk.
CHS vs. Cyclic Vomiting Syndrome
CHS looks almost identical to cyclic vomiting syndrome (CVS), a condition that causes the same pattern of recurrent vomiting episodes. The key difference is cannabis use. CHS happens specifically in heavy, long-term users and improves when they quit. CVS occurs independently of cannabis. Another distinguishing feature: in CHS, the stomach empties more slowly than normal, while in CVS it often empties too quickly. The hot shower compulsion is also much more characteristic of CHS. If you’re experiencing these symptoms and use cannabis regularly, the connection is worth considering.
The Only Reliable Way to Stop It
Quitting cannabis is the only proven way to end CHS cycles permanently. People who stop using typically see their symptoms resolve completely, though it can take weeks to months for the body to clear stored THC from fat tissue and for the receptor system to reset. During that time, occasional nausea may linger.
The challenge is that many people with CHS have used cannabis for years and find quitting difficult. Resuming use, even after a long break, reliably brings the symptoms back. There is no way to continue using cannabis and prevent CHS from recurring once it has developed. Reducing the amount or switching to lower-potency products has not been shown to reliably prevent episodes.