This meta-study examined the effectiveness of the "non-euphoric" cannabinoids CBD, CBDA, and CBDA-ME (methylated) in managing nausea and vomiting. It was published in August 2021 in the journal Cannabis and Cannabinoid Research.
A few key quotes from the study:
"CBD has demonstrated efficacy in reducing nausea and vomiting, with CBDA and CBDA-ME [methylated] being more potent."
"CBDA is effective in reducing motion-induced vomiting, whereas CBD is not."
"In the house musk shrew, CBD produces a biphasic effect, with low doses (5, 10 mg/kg, i.p., s.c.) suppressing, and high doses (25, 40 mg/kg, i.p.) potentiating toxin-induced vomiting. "
"Similarly, in vitro studies suggest that CBD and CBDA may exert positive anticancer effects that may enhance the effectiveness of chemotherapeutic agents."
An easy, inexpensive and solvent-less way to get CBDA is by simply purchasing CBD hemp kief. Most of the "CBD" in kief (and flower) is in the form of CBDA, which converts to CBD when heated. Mix the hemp kief with something else, or take it as is - just don't apply any heat. Putting it under your tongue (kief tincture) for several minutes will help the effects start even faster.
The study also commented on the evidence for the "euphoric" cannabinoid THC. Although there is strong human and animal evidence that THC can reduce nausea, one study found that high doses of THC equivalent to 750mg for a 165 lb. person (10mg/kg) actually "promoted" nausea in rats. That is an EXTREMELY high dose, and is roughly equivalent to the amount of THC in 5 grams of 15% THC flower. At a 25% bioavailability rate for smoking, the user would need to smoke 20 grams, or almost 3/4 of an ounce of flower to get that much THC into their bloodstream.
Nonetheless, it demonstates the biphasic nature of THC - a large dose can produce the OPPOSITE effects as a small dose.