Does Weed Help With Nausea and Vomiting?

Sophia Delphi August 09, 2022 - 9 min read
Fact Checked
Illustration of Woman sick with Nausea

Well before medical marijuana was legalized in more than two-thirds of American states, it was well-established that several types of patients could benefit from the use of cannabis.

One group suffered from glaucoma, and research dating back to the 1970s showed that THC reduced intraocular pressure, a major contributing factor to the disease’s progression.

The other group had cancer.

More than half of all new cancer patients receive chemotherapy as a treatment for their disease. And there’s an extremely common side effect of chemotherapy: CINV, or chemotherapy-induced nausea and vomiting.

For a large number of those patients, marijuana effectively treated CINV. Ever since the 1980s, they had to use less effective but FDA-approved synthetic marijuana pills or buy weed on the black market. Some still do, but cancer patients in legal states can now easily purchase medical marijuana.

Should they? Does weed really help with nausea? And does it help non-cancer patients who suffer from the problem?

Let’s find out.


Speak to someone who’s had to undergo chemotherapy, and the first thing they tell you about may not be hair loss. Many will describe the 24 hours of hell following each treatment.

As many as 40 percent of chemotherapy patients suffer severe episodes of nausea and vomiting almost immediately after their chemo session. The physical causes of CINV are complicated, but they involve the release of the neurotransmitters serotonin and dopamine and the way they’re handled by the nervous system, the brain, and the stomach.

The medical world’s first-line treatments for CINV are so-called antiemetic medications, most of which target the body’s serotonin and dopamine receptors. Corticosteroids and other prescription meds are sometimes effective as well.

Sadly, those medications often provide only partial relief or don’t help at all.

In the 1970s, the first study was published showing that THC provided effective relief for the disabling symptoms of CINV. Subsequent research confirmed the findings, and in 1985, the Food and Drug Administration approved the use of two synthetic marijuana pills (nabilone and dronabinol) to treat chemotherapy-induced nausea and vomiting.

Systemic reviews have shown those types of medically-produced, synthetic weed to be superior to traditional medical treatments for CINV, but they can also produce severe side effects, including depression, low blood pressure, and paranoia.

Many chemotherapy patients who smoked marijuana instead of taking the THC pills, on their own or with the encouragement of their doctors found that they experienced greater relief without most of the side effects of synthetic weed.

That’s encouraging, but what does science say on the subject?

Weed and CINV-Related Nausea

Not many studies have examined the effectiveness of inhaled cannabis smoke on CINV. Frankly, that’s because most researchers don’t want to look into the effects of a substance that the federal government still considers illegal.

However, a review of available CINV research was published in the European Journal of Pharmacology in 2014. It concluded that “cannabinoids block both acute and delayed emesis” and the nausea that precedes it. (Emesis is medical-speak for vomiting.)

Cannabinoids, of course, refer to both THC and the non-psychoactive CBD in cannabis, and there’s been some research finding that CBD may also be a potential weapon against nausea.

The reason that cannabinoids can help the body fight nausea and vomiting is interesting.

You probably know that there’s an extensive endocannabinoid system (ECS) throughout the body. It regulates a number of bodily functions through the interaction of neurotransmitters known as endocannabinoids and ECS receptors.

The cannabinoids in weed are almost identical in structure to an important endocannabinoid produced by the body — and that allows THC and CBD to interact with ECS receptors. The interaction is what allows you to get high or experience physical relief when you use marijuana.

It turns out that the same ECS receptors are involved in the regulation of nausea and vomiting, so it’s not surprising to learn that both THC and CBD have been found to be effective inhibitors in animal studies designed to replicate emetic responses in humans.

It also makes sense that inhaled cannabis smoke would be more effective at stopping nausea than synthetic marijuana taken orally since the THC in smoke is absorbed and takes effect within minutes. Any THC that has to pass through the gastrointestinal system can take an hour or longer to be digested and interact with ECS receptors.

That pretty much explains why weed can help with nausea caused by chemotherapy, but it leaves one important question.

Can Weed Help With All Cases of Nausea?

A woman at home with nausea use weed to help

The answer appears to be “yes.”

A recent study on the matter was done at the University of New Mexico and published in the Journal of Clinical Gastroenterology. Nearly one thousand nausea sufferers, with widely varying causes for their distress, participated in self-administered sessions.

Their symptoms were measured on a 1-10 scale before, during, and after using weed. And more than 96% of participants reported their nausea decreased by an average of four points on the ten-point scale within one hour.

Among the specific findings:

  • Significant symptom relief began five minutes after consumption and continued to improve after that.
  • Flower and weed concentrates provided the greatest relief.
  • Joints were associated with more effective relief than pipes or vaporizers.
  • Sativa and hybrid strains were more effective at relieving nausea than indica strains, and higher-THC/lower-CBD strains provided the most relief.

Several illnesses and diseases have been discussed or investigated in connection with nausea and cannabis as well.


A form of synthetic marijuana is prescribed for HIV/AIDS patients who lose their appetite as a side effect of the disease, and weed has been shown to relieve a number of HIV/AIDS side effects that lead patients to skip their prescribed medications. Nausea wasn’t specifically studied, but it is one of those side effects.

And a large-scale questionnaire administered to HIV-positive participants showed that 93% reported decreased problems with nausea after cannabis use.

Motion Sickness

The efficacy of marijuana as a treatment for nausea associated with motion sickness has not yet been rigorously studied.

However, research into the body’s reaction to a NASA parabolic flight simulator found that the participants’ endocannabinoid levels dropped significantly when they became nauseous. The clear implication is that improved ECS communication — which might be provided by the cannabinoids in cannabis — could help the body fight nausea caused by motion sickness.

Does Weed Help With Nausea: FAQ

Q: Could weed help pregnant women with nausea they often experience during the first trimester?
A: It’s possible, but pregnancy is one of the only nausea-causing conditions for which weed may be contraindicated. One reason is that a mother’s cannabis use appears to have negative effects on fetal neurological development and future mental health. The other is that there seems to be a correlation between nausea during pregnancy and marijuana use. One study found that expectant mothers with serious nausea issues were more likely to have smoked during their pregnancy. Some researchers believe the issue may be due to cannabis hyperemesis syndrome accelerated by pregnancy.

Q: OK, so what is cannabis hyperemesis syndrome?
A: Hyperemesis is a severe vomiting problem that can last for 24-48 hours after smoking. A small number of regular, long-term weed smokers actually find that they have reoccurring problems with nausea, vomiting, abdominal pain, and dehydration, and it’s likely due to cannabis hyperemesis syndrome. No one’s sure exactly what causes the issue, but it’s usually blamed on either overstimulation of the ECS or genetics. And sadly, the only “cure” is to stop smoking.


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