Oral cannabinoid drugs ease chemotherapy-induced nausea and vomiting. Smoked or vaped cannabis has no standard dose and no FDA approval for nausea. If you use dispensary cannabis for nausea, start at 2.5 mg to 5 mg of THC, wait 2 hours before any second dose, and tell your doctor.
The strongest evidence: chemotherapy nausea
A 2017 review by the National Academies of Sciences, Engineering, and Medicine examined more than 10,000 abstracts. It found substantial evidence that oral cannabinoids reduce chemotherapy-induced nausea and vomiting in adults. Evidence for smoked cannabis was weaker. Most trials of smoked cannabis had small sample sizes and no placebo control.
FDA-approved drugs
Two synthetic THC drugs are approved in the United States for chemotherapy-induced nausea and vomiting that has not responded to other antiemetics.
best cannabis strains for nausea
- Dronabinol (Marinol, Syndros): a capsule and an oral solution. Approved 1985.
- Nabilone (Cesamet): a capsule. Approved 1985.
Both contain synthetic THC. The FDA has not approved the cannabis plant for any medical use. Federal law classifies cannabis as a Schedule I drug.
best cannabis strains for nausea
How THC acts on nausea
THC binds CB1 receptors in the brain and gut. CB1 receptors sit in the dorsal vagal complex and the area postrema, the region that triggers the vomiting reflex. CBD binds CB1 receptors with low affinity. Human evidence for CBD alone as a nausea treatment is thin.
Dosing and onset by method
- Inhaled (flower, vape): onset 1 to 10 minutes. Effects fade in 1 to 3 hours.
- Oral (edible, capsule, tincture): onset 30 to 120 minutes. Effects last 4 to 8 hours.
- Sublingual tincture: onset 15 to 45 minutes.
Edible THC converts in the liver to 11-hydroxy-THC, a compound with stronger psychoactive effects than inhaled THC. A dose that feels mild at 30 minutes can feel intense at 2 hours. Buy products with the THC dose printed on the label. In US legal markets, packages list milligrams of THC per package and per serving.
Side effects
- Drowsiness, dizziness, dry mouth, red eyes, fast heart rate.
- Anxiety or paranoia at high doses.
- Impaired memory and coordination for several hours.
- High THC doses can increase nausea in some users.
Cannabis interacts with drugs that depress the central nervous system: opioids, benzodiazepines, alcohol, and sleep aids. CBD inhibits the CYP3A4 and CYP2C19 enzymes, which can raise blood levels of some prescription drugs.
Cannabinoid hyperemesis syndrome
Daily, long-term cannabis use causes cannabinoid hyperemesis syndrome (CHS) in some users. Symptoms: repeated vomiting, abdominal pain, and nausea that eases with hot showers or baths. Vomiting stops after the person quits cannabis. US hospital discharge data show emergency department visits for CHS rose after state legalization. If hot showers control your nausea, CHS is a likely cause. Stop cannabis and see a doctor.
See a doctor first for these cases
- Nausea that lasts more than 2 weeks.
- Vomiting blood or material that looks like coffee grounds.
- Weight loss, severe abdominal pain, or signs of dehydration.
- Pregnancy. Cannabis is not recommended in pregnancy.
- People under 21. Cannabis is not legal for this group in any US state.
Prescription antiemetics such as ondansetron are first-line treatment for most nausea. Cannabis is an add-on for specific cases, not a replacement for standard care.
What is unknown
No standard dose of smoked cannabis exists. Clinical trials use pills with a known THC content. Flower and vape products vary by strain, batch, and device temperature. Research on CBD for nausea in humans is limited. Long-term effects of daily cannabis use on the digestive system remain unclear.