I had this for ten years before it had a name.
It got a code in October 2025, twenty one years after the first paper. Everything below is what I did not know.
what changed
The plant did not stay the same.
One or two percent THC in the seventies. Around twenty two percent in dispensary flower now, and flat there since 2017. Concentrates measure seventy to eighty five. Same species, a completely different dose, and nobody handed me that number on the way in.
the first sign
It starts with a morning you can explain away.
Sick on waking, fine by two in the afternoon. There is always something else it could be. That stage can run for months, and every month it runs makes the real answer sound less likely.
the episode
Then a night when the shower is the only thing that works.
Vomiting that will not stop, and hot water that does what no medication does. Just under half of people whose symptoms fit this say heat helps at all, and people with cyclic vomiting who never touch cannabis do it too. It is a clue, not proof, and nobody has proven why it works.
The other thing that helped I have never seen written down anywhere. My body told me to go outside and lie in the grass in my boxers, as much skin on the ground as I could get, and soak in the sun. Hugging a big old tree did more for me than hugging a person did. I have no idea why, and I am not going to pretend I do.
the years
You will be told your tests are normal.
Seventeen point nine emergency room visits. Around seventy seven thousand dollars. And of everyone whose symptoms fit this, only 11.5 percent have ever been told what it is.
the search
Everything comes back clear, and that is the problem.
Scopes, scans, bloodwork, all normal. This is a diagnosis of exclusion, so clean results are not a dead end. They are the requirement. I have never once seen that explained to anyone on the way out of an appointment.
the name
On October 1, 2025, it got a code.
R11.16. Cannabinoid hyperemesis syndrome, issued by the CDC's National Center for Health Statistics. A code sounds like paperwork. It means a doctor can write it down, bill for it, and find it in the book. Before October there was nowhere to put it.
the turn
It stops when you stop.
Not fast and not easily. Days to a few weeks for most people, one to three months for a meaningful group, and a tail beyond that which research has never measured. Close to eighty percent relapse at least once. Full cessation is still the only thing that reliably ends it, and I would rather tell you that than something easier to hear.
before anything else
Go to the emergency room before you trust this page.
A diagnosis of exclusion is only the right answer after the dangerous things are ruled out. Pancreatitis, a bowel obstruction, and a short list of other conditions feel exactly like this from the inside. If this is new, if the pain is severe, or if you cannot keep water down, that is a hospital, not a website.
Written by Kole Purdy, who has had this for ten years. Every number on this page is cited on the evidence page.