Cannabis is often thought of as harmless or even helpful for nausea. But did you know that heavy, long-term cannabis use can sometimes cause severe nausea and vomiting? This condition is called Cannabinoid Hyperemesis Syndrome (CHS), and it’s becoming an increasingly common reason people land in the emergency department.
What Is Cannabis?
Cannabis—also known as marijuana, weed, or pot—is a plant that contains compounds called cannabinoids. The most well-known is THC (tetrahydrocannabinol), the chemical responsible for the “high” people feel. Cannabis can be smoked, vaped, or eaten in edible products.
Some people use it for recreational purposes, while others use it for medical reasons such as pain, sleep, or nausea. However, frequent or heavy use can have harmful effects, including the development of Cannabinoid Hyperemesis Syndrome (CHS).
What Is CHS?
CHS is a disorder linked to frequent cannabis use (usually several times per week for a year or more). It causes sudden, repeated episodes of:
- Intense nausea
- Severe vomiting
- Stomach pain
A strange but common feature is that symptoms often improve temporarily with hot showers or baths. The only long-term solution, however, is stopping cannabis use altogether.
Why Does It Happen?
The exact cause isn’t fully understood. Researchers believe high levels of cannabis may actually flip its usual effect—making the brain and gut more likely to trigger vomiting instead of preventing it. This may involve changes in the endocannabinoid system, which regulates both digestion and body temperature.
How Is CHS Treated?
Standard nausea medications usually don’t work. Instead, doctors may recommend:
- Topical capsaicin cream (applied to the skin of the upper abdomen)
- Antipsychotic medicines such as haloperidol or olanzapine
- Benzodiazepines for short-term relief
Opioids should be avoided, as they can make symptoms worse. The most important treatment is completely stopping cannabis use, which is the only way to prevent symptoms from coming back.
CHS and Pregnancy
Pregnancy adds another layer of concern. CHS can look very similar to hyperemesis gravidarum (severe pregnancy nausea and vomiting), which makes diagnosis tricky. But unlike hyperemesis, CHS is tied directly to cannabis use.
Cannabis use in pregnancy is risky because THC crosses the placenta, exposing the baby. Studies link cannabis use in pregnancy to:
- Low birth weight
- Preterm birth
- Higher chances of needing NICU care
Because of these risks, the American College of Obstetricians and Gynecologists strongly recommends avoiding cannabis during pregnancy and breastfeeding.
CHS Treatment in Pregnancy
Managing Cannabinoid Hyperemesis Syndrome (CHS) during pregnancy can be especially challenging. The main and most effective treatment is still stopping cannabis use completely. Without abstinence, symptoms almost always return.
Because CHS often looks very similar to nausea and vomiting of pregnancy (or hyperemesis gravidarum), doctors will often start by using the same medications we typically use in pregnancy to try to improve symptoms, such as:
- Ondansetron (Zofran) – commonly prescribed for severe nausea and vomiting in pregnancy
- Metoclopramide (Reglan) – helps with stomach emptying and nausea
- Promethazine (Phenergan) – another anti-nausea option
- Scopolamine patch (Scopolamine/Transderm-Scop) – occasionally used for motion sickness–type nausea
However, these medicines are often less effective in true CHS, and symptoms may not improve until cannabis use stops. For pregnant patients, the focus is always on keeping the mother hydrated, nourished, and safe, while also protecting the baby’s health.
Why It Matters
CHS now accounts for nearly 1 in 10 cases of cyclic vomiting syndrome seen in hospitals. Many patients don’t believe cannabis could be the cause of their nausea, which delays diagnosis and treatment. But awareness is growing, and recognizing the condition early can prevent serious complications like dehydration, esophageal tears, or poor pregnancy outcomes.
Quick FAQ on CHS
❓ How do I know if it’s CHS and not something else?
If you use cannabis regularly and experience repeated vomiting episodes that improve with hot showers, CHS is a possibility. Only your healthcare provider can confirm the diagnosis.
❓ Does CHS go away if I stop cannabis?
Yes. Symptoms usually resolve completely after extended cannabis abstinence. If you start using again, symptoms often return.
❓ Can cannabis help nausea in pregnancy?
No. While some people think it helps, cannabis can actually worsen vomiting if CHS develops and may harm the baby’s growth and health.
❓ What should I do if I think I have CHS?
See a healthcare provider. Do not ignore repeated vomiting, especially if you’re pregnant. Stopping cannabis is the most effective treatment.
✅ Takeaway: If you or someone you know experiences unexplained vomiting while using cannabis regularly—especially during pregnancy—talk to your healthcare provider. CHS is real, it’s serious, and it can be managed with the right care.