Hyperemesis is the medical term for excessive vomiting. After long-term, frequent use, cannabis can have a paradoxical effect: instead of helping against nausea, it then triggers it. In cannabis hyperemesis syndrome, there are recurring phases of severe nausea, persistent vomiting and abdominal pain. Nausea or abdominal pain often come before the bouts of vomiting. Many of those affected have already been through such phases several times, months apart, before the cause is recognised.
A typical feature: medication against vomiting usually helps little, while hot showers or baths relieve the symptoms. This is considered an important feature for distinguishing the syndrome from other causes. Other illnesses still have to be ruled out by a doctor.
Many of those affected even use more during this phase because they believe cannabis helps against the nausea. That makes it worse. The effective treatment is simple: stop using.
Remember: Recurring vomiting with regular use that gets better with a hot shower: have it checked by a doctor and stop using.
More on this: When it gets too much