Cannabinoid Hyperemesis Syndrome
What I wish I'd known ten years ago.
A calm, honest guide for anyone standing in a hot shower at 3 a.m. wondering what is wrong with them, written by Kole Purdy, who spent a decade there.
You are not making it up. You are not the only one. And there is a way out.
CHS is real and it has a name. It has been in the medical literature since 2004, and US medicine gave it its own diagnostic code, R11.16, in October 2025. Most doctors still have never said it out loud.
In the one emergency-room study that measured it, nearly one in three frequent cannabis users met the criteria. That's a small, self-reported sample, but it was the first time anyone counted. That's why this page exists.
Where are you right now?
Start with the one that sounds like tonight.
- Sick right nowMid-episode, can't stop throwing up. Start here.→
- Not sure it's the weedPart of you doesn't buy it. Read the evidence, weaknesses and all.→
- Just got told at the ERSomeone finally named it. Here's what it actually is.→
- Trying to quitFirst 30 days. What's coming, so nothing blindsides you.→
- Relapsed, feel ashamedAlmost everyone does. It isn't the end. Read this.→
- Watching someone you loveA partner or parent, feeling helpless. There's a way to help.→
What CHS actually is
Cannabinoid Hyperemesis Syndrome is what happens when years of heavy cannabis use flip the drug from being anti-nausea to being the cause of it. Small doses calm the stomach; chronic high doses eventually re-wire the receptors that regulate vomiting, and one day the same plant that used to help you starts making you violently sick in cycles.
The cruelest part is the timing. It usually hits the next morning, not the moment you use, and a little more cannabis genuinely calms it for a while, so the thing causing it is also the thing that seems to fix it. That's how it hides for years. (Throwing up once from too big a dose is a normal overdose, not CHS. CHS is the cycle that keeps coming back.)
The condition is real. It has been in the medical literature since 2004, US medicine gave it its own diagnostic code in October 2025 (R11.16), and the only cure anyone has found is complete cannabis abstinence. If you want the full case, with sources, the evidence page lays it all out.
The three phases
Phase 1
Prodromal
Early morning nausea. A little abdominal tightness. Fear of throwing up, but you rarely do. Most people use more cannabis here because it seems to help, and that's the trap that accelerates everything.
If you're a daily user waking up with morning nausea, heartburn, loose stools, anxiety, or hot and cold sweats, that cluster is the early warning. This is the easiest point to stop, and the hardest one to take seriously.
Phase 2
Hyperemetic
Overwhelming, unstoppable vomiting. Retching every few minutes. Diffuse abdominal pain so severe patients scream through it (the ER slang is "scromiting"). Compulsive hot showers are the only thing that touches it. This is the ER phase.
Phase 3
Recovery
Begins the moment you stop, for good. Acute vomiting usually eases within 10 days. The full nervous-system reset is slower. Any resumption of cannabis, including edibles, vapes, and in rare reported cases even CBD, can restart the cycle from Phase 2.
Five things that actually help
Ranked by how consistently patients and studies report success. Nothing here is medical advice. It's what the community and the research so far agree on.
CHS is a diagnosis of exclusion. The same vomiting and belly pain can be appendicitis, a bowel obstruction, pancreatitis, a diabetic emergency, or, if you're pregnant, something that needs care now. If you have blood in your vomit or stool, severe or one-sided pain, a high fever, chest pain, confusion, or no urine for 12+ hours, or you're pregnant, this may not be CHS. Go to the ER. The tips below are for after those are ruled out.
- 1
Hot showers, hot baths
Water hot enough to be almost uncomfortable, over the torso. Long sessions. The leading explanation is that heat stimulates a nerve receptor (TRPV1) that chronic cannabis seems to dull. Whatever the mechanism, this is the single most reported relief in every study.
77 to 92% report relief - 2
Topical capsaicin cream
Over the counter, 0.025 to 0.1 percent (Zostrix, Capzasin). Rub a thin layer on your stomach. Same idea as the hot shower, without needing to be in the water. Wash your hands right after. Wait for the burn, then the relief.
Used in ERs since the mid-2010s - 3
Electrolytes and small sips
An oral rehydration drink, Pedialyte, or salted broth. Cheap and simple beats fancy. Not a cure, but dehydration is what turns a bad night into a hospital stay, and in CHS it can be hard enough on the kidneys to cause real damage.
Prevention, not rescue - 4
Ginger. Candies, tea, capsules
Won't stop a full episode, but takes the edge off mild prodromal nausea and is one of the few things that feels good in the early days of quitting.
Best for early / mild days - 5
The ER, and how to be heard
If you're past 24 hours without keeping fluids down, go. You don't have to diagnose yourself, and you shouldn't demand specific drugs. Tell them the facts and ask them to help: "I'm a heavy daily cannabis user, hot showers relieve this, and I think it may be Cannabinoid Hyperemesis Syndrome. Please rule out other causes, and can we consider the treatments the research supports?" For the record, standard anti-nausea drugs like Zofran often underperform here; the ones that tend to work are haloperidol, droperidol, or olanzapine plus topical capsaicin (haloperidol beat Zofran in a head-to-head trial); and guidelines say opioids shouldn't be first-line and can make it worse. Our printable ER card says all of this for you, in a way that helps the doctor instead of arguing with them.
Ask, don't demand
If you're mid-episode right now
A short checklist for the next hour. Tap what you've done.
0 of 7 done
For someone you love
If you're a partner or a parent watching this happen, you are not imagining how bad it is, and you're not powerless.
What you can do
Believe them, out loud. Half the cruelty of CHS is that it looks like something they're doing to themselves, and the people around them often say so. Hearing "I believe you, this is a real named condition" from someone who loves them is worth more than another lecture.
During an episode: help them into a hot shower, keep small sips of electrolytes nearby, and watch for the red flags above. If they can't keep fluids down for a day, or you see blood, confusion, or no urine, that's the ER.
The hard part: you can't make someone quit. What breaks through is rarely a fight, it's the pattern becoming undeniable, usually after they stop and feel better, then use and get sick again. Point them at that pattern gently, share the evidence page, and set your own boundaries with support (Al-Anon's framework fits this well). You can love someone and still not carry this for them.
What recovery actually looks like
Nobody tells you the timeline. Here it is, honestly. It gets a lot better than you think, and slower than you want. Quitting also brings its own withdrawal, the worst of it days 2 to 6, easing over two to four weeks, so if sleep, appetite, or mood get rough right as the vomiting stops, that's normal and it passes. That withdrawal can even come with some nausea, which can trick you into thinking the CHS is back. It isn't. You can't get CHS from quitting, only from using.
- Day 0Last use
- Day 10Acute vomiting ends
- Week 4Sleep and appetite come back
- Month 3Food tastes right. Most people feel normal
- Month 6Even the slow cases level out
Timelines vary with how long and how heavily you used. Ten years in, mine ran long. It still ended. One honest flag: if you've fully quit for months and still feel sick, that may not be CHS anymore, get a second opinion for something else.
If you've ever found yourself standing under a scorching hot shower at 3 a.m. because it was the only thing keeping you from vomiting again ... you are not alone.from a CHS patient community
About "just one hit"
Once your body has learned this, it doesn't forget.
A 2022 survey of 205 people with CHS found 79% returned to cannabis at some point after their diagnosis, and a newer survey of over 1,100 people found the same shape: only 39% quit for good, and 70% of the people who stopped and tried again had it come back. If that's you, you're the rule, not the failure, and it isn't the end. But most who go back end up right in Phase 2. There is no safe test dose. Edibles are not a workaround. High-THC vape carts are the worst version. Full abstinence is the only stable place. It gets easier, but it takes months, not days, and the first four weeks are where most people slip. Have a plan for sleep, a plan for social pressure, and someone who knows what you're doing.
The evidence
For the part of you that still doesn't believe.
Twenty years of research, the potency story, the charts, and the honest parts too, including where doctors still disagree. Built to be read by a skeptic.
See the whole case →